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UNIVERSITY OF MINNESOTA

This is to certify that I have examined this copy of a master’s project by

Reuben Ray Collins

And have found that it is complete and satisfactory in all respects, and that any and all

revisions required by the examining committee have been made.

__________________________________________________________

Name of Faculty Advisor

__________________________________________________________

Signature of Faculty Advisor

__________________________________________________________

Date

GRADUATE SCHOOL

Evaluation of a Roundabout at a Five-Way Intersection:

An Alternatives Analysis Using Microsimulation

A PROJECT

SUBMITTED TO THE FACULTY OF THE GRADUATE SCHOOL OF

THE UNIVERSITY OF MINNESOTA

BY

Reuben Ray Collins

IN PARTIAL FULFILLMENT OF THE REQUIREMENTS

FOR THE DEGREE OF

MASTER OF SCIENCE

David M. Levinson

Department of Civil Engineering

February 2008

Reuben Collins Plan B Project February 2008

i

TABLE OF CONTENTS

1.0 INTRODUCTION ............................................................................................................. 1

2.0 LITERATURE REVIEW ..................................................................................................... 1

3.0 CASE STUDY ................................................................................................................. 11

4.0 DATA COLLECTION....................................................................................................... 16

5.0 MICROSIMULATION MODEL ....................................................................................... 21

6.0 MODEL VALIDATION .................................................................................................... 24

7.0 ALTERNATIVES ANALYSIS ............................................................................................ 30

8.0 MEASURE OF EFFECTIVENESS - DELAY ........................................................................ 41

9.0 MEASURE OF EFFECTIVENESS – TRAFFIC DIVERSION ................................................. 51

10.0 DISCUSSION ............................................................................................................... 54

WORKS CITED .................................................................................................................... 58

APPENDIX .......................................................................................................................... 60

ACKNOWLEDGEMENTS

The author thanks Professor David Levinson for guidance and suggestions on all aspects

of this study. Professor Henry Liu provided invaluable advice regarding data collection

and provided the equipment necessary to do so. John Hourdos and Ted Morris from the

Minnesota Traffic Observatory provided guidance and support regarding the

implementation of AIMSUN. Darryn Proch provided the data from Minneapolis Public

Works. Finally, the author wishes to thank the students of CE 8200 during the Fall 2007

semester for providing initial feedback and questions while this work was in progress.

Reuben Collins Plan B Project

1

1.0 INTRODUCTION

In recent years, roundabouts have become an increasingly popular traffic management

option in urban areas. As of April 2006, there were 17 known roundabouts in

Minnesota with another 10 under construction (City of Richfield 2006). Many

communities are creating roundabouts hoping to reduce vehicle delay, reduce vehicle

emissions, and make cities a more pleasant place to live. Minneapolis has only one

existing roundabout, but several more have received consideration in the past,

particularly in locations where local streets do not meet at 90 degree angles and where

there are more than 4 approaches.

The ability of a roundabout to reduce vehicle delay under certain conditions is fairly well

known within the traffic operations community. Numerous studies have demonstrated

a reduction in congestion and delay after the implementation of a roundabout.

However, existing literature is lacking in terms of details regarding under what

conditions a roundabout is an appropriate alternative, and what factors might preclude

the implementation of a roundabout. The vast majority of existing literature considers

only intersections with four approaches intersecting at right angles. Analytical models

have not yet been fully developed to explain roundabout operations. Instead, most

models rely on empirical evidence. This is especially true when considering roundabout

operations in the U.S., where typical drivers are inexperienced with roundabouts.

With the academic knowledge of U.S. roundabout operations still in relative infancy

(compared to signalized intersections), planners and engineers are sometimes hesitant

to implement roundabouts in their communities. Without reliable analytical models,

planners and engineers must utilize other methods of estimating the effectiveness of a

roundabout in a specific location. Microsimulation provides planners and engineers

with the ability to make informed predictions about the effectiveness of a roundabout

while taking into account location specific parameters.

This study considers the effectiveness of a roundabout at reducing vehicle delay using

an intersection in Minneapolis, MN, as a case study. This study differs from similar

studies in that the case study involves several complicating factors whose impacts on

roundabout operations are not fully understood. The complicating factors include the

number of approaches (5 instead of the usual 4), relatively high pedestrian and bicycle

volumes, and highly directional flow patterns during peak periods. The next section

provides an overview of relevant literature, followed by a description of the case study

location. Section 4 describes the data collection process, followed by Sections 5 and 6,

which discuss details relating to the microsimulation model. Section 7 describes the six

alternatives considered in this study. Sections 8 and 9 provide an analysis of two

measures of effectiveness. Finally, Section 10 provides a discussion of the alternatives.

2.0 LITERATURE REVIEW

There have been several types of circular intersections in recent history. Rotaries, not

uncommon in the U.S. until 1960 featured circulatory speeds of 30 mph or higher, and


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were often large, sometimes 300 feet in diameter. They often featured yield to-the-

right rules, meaning circulating traffic yields to entering traffic. Neighborhood traffic

circles are commonly built at the intersection of small, local roads for traffic calming or

aesthetic purposes. They usually feature uncontrolled access, yield-to-the-left rules, and

in some cases, permit left turns traveling clockwise through the circulating roadway.

Modern roundabouts, hereafter referred to only as roundabouts, always feature yield-

to-the-left rules, usually incorporate some level of vehicle deflection and channelization,

and typically feature operating speeds less than 30 mph (FHWA 2000).

Most examples of existing roundabouts are found outside of the United States.

Roundabouts are more commonplace in Europe and Australia than in the U.S. Thus it is

not surprising that much of the existing literature regarding roundabout operating

characteristics uses case studies outside the U.S. The body of literature regarding

domestic roundabouts has grown in recent years, however. It is important to remember

that drivers abroad may react differently towards roundabouts than drivers in the U.S.

The relative inexperience of most domestic drivers with roundabouts should cause

engineers and planners to question whether the outcome of roundabout conversions in

the U.S. will be similar to roundabout conversions in areas where drivers are more

experienced with them.

Design guidelines within the U.S. are still developing, though they are becoming

increasingly common. Still, many states, including Minnesota, have not yet fully

adopted roundabout design guidelines. The Minnesota Department of Transportation

(MnDOT) has, however, pre-approved six consulting firms to provide roundabout design

standards services. Until formal design guidelines can be adopted, MnDOT relies almost

entirely on the Federal Highway Administration (FHWA) guidelines entitled

Roundabouts: An Informational Guide (FHWA 2000). The FHWA guidelines, in turn,

frequently cite the Highway Capacity Manual (HCM) (Transportation Research Board

2000).

Intersection analysis models can be classified into two types: empirical and analytical

models. Empirical models use observations at many different intersections under

different conditions to develop regression equations that match intersection

characteristics with intersection capacity. Analytical models estimate capacity based on

gap-acceptance relationships that do not require observations under congested

conditions (Stanek and Milam 2005).

The HCM provides an analytical approach to evaluating roundabouts using gap

acceptance theory for each approach. The manual does not provide any guidance,

however, regarding intersection delay, and the roundabout discussion is limited to one-

lane roundabouts. The manual does not provide guidance regarding roundabouts with

two or more lanes because of a lack of experience in the U.S. The FHWA provides

guidelines for roundabouts based on empirical data from European sources and

academic research. Guidelines for calculating control delay at high-capacity


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roundabouts is given, but the equation is based on observations from the United

Kingdom.

The FHWA guidelines list several computer software products, both macroscopic and

microscopic. Numerous studies have attempted to determine which software packages

most accurately represent roundabout operations. This comparison can be made on

two levels: first, comparisons between microscopic and macroscopic models, and

second, comparing microscopic models with other microscopic models and macroscopic

models with other macroscopic models.

Stanek and Milan compared two macroscopic models (RODEL and aaSIDRA) with two

microscopic models (VISSIM and Paramics). They found widespread disagreement

between all four models and suggest reasons for the discrepancies based on

methodology. They conclude that microscopic models require much more time, effort,

and data to accurately simulate roundabout models, but they can “better match

unusual project features” and can be better calibrated to local conditions. They

recommend that macroscopic models be utilized to analyze high-capacity roundabouts

only for unsaturated conditions or for isolated locations with standard geometry.

Microscopic models should be used when congestion is present and when encountering

unique geometry. In addition, microsimulation tools allow the user to model nearby

intersections (Stanek and Milam 2005).

Choosing between the various microsimulation tools is not as straight forward. A 2005

report completed at the University of Minnesota suggests a process by which the user

rates the operability of each simulation tool under consideration on a scale from one to

ten. Then, the user applies a weight to that area of functionality depending on the

perceived importance of the specific function. The process takes into account

qualitative as well as quantitative criteria

(Xiao, et al. 2005). This methodology allows users much freedom when selecting a

simulation software product.

A study at the University of Maryland compared the roundabout functionality of

microsimulators Paramics, VISSIM, and AIMSUN in a study completed in 2005. The

study constructed the same roundabout in all three simulators, and used synthetic O/D

traffic demand and compared the output. The traffic demand was increased by 10%

and 30%, and again compared the output each time. In general, the study concluded

that Paramics provided the most convenient and easy to use functionality, although

VISSIM provides easier and more up-front access to direct roundabout parameters.

AIMSUN, for better or for worse, tended to concentrate random errors on congested

links. All three simulators had apparent drawbacks: VISSIM tended to estimate much

larger levels of congestion throughout the network than the other two, while Paramics

and AIMSUN both appeared to provide various output statistics that were inconsistent

with other output parameters. Ultimately, the study concluded that all three simulators

have strong points and weak points, but that one cannot immediately be considered

“better” than another (Chang 2004).


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An outstanding question regarding roundabout simulation is whether it is appropriate to

use simulation packages with normal gap-acceptance models. Most software packages

treat gap-acceptance processes in roundabouts the same as at conventional priority

intersections. This assumption has not been verified in any substantial form

(Krogscheepers and Roebuck 1999).

One of the most authoritative and comprehensive study of roundabouts in the U.S. is

the 2007 NCHRP Report No. 572 (Transportation Research Board 2007). This extensive

study combines case studies from the U.S. with case studies from Europe and

elsewhere, and attempts to create models that accurately describe roundabout

performance in the U.S. One component of the study compared observed roundabout

approach capacities with predicted capacities calculated using Australian, British,

German, French, and Swiss models, as well as HCM and FHWA models based on

European experience. In nearly every case, the existing models overestimated the

capacity of U.S. roundabouts. The report states, “Although the sample sizes are quite

small, the international models clearly do not describe U.S. conditions well without

further calibration. U.S. drivers appear to be either uncertain or less aggressive at

roundabouts, and hence roundabouts currently appear to be less capacity efficient than

the international models would suggest.”

The NCHRP report uses empirical and analytical methods to develop a single-lane

capacity model based on the volumes of entering traffic and circulating traffic, as well as

critical headway and follow-up headway. The report suggests the following model:

c = α*e-β vc

where

c = entry capacity (veh/h)

vc = conflicting circulating traffic (pcu/h)

α = 3600/tf

β = (tc - tf /2)/3600

tc = critical headway (s)

tf = follow-up headway (s).

The report uses empirical data to suggest a critical headway of 5.1 seconds and a follow-

up headway of 3.2 seconds. Using these suggested values, the single lane capacity

model reduces to:

c = 1130*e(-0.0010vc)

where

c = entry capacity (veh/h)

vc = conflicting circulating traffic (pcu/h).

Applying the same methodology to two lane roundabouts is more challenging.

Estimating the capacity of a two-lane roundabout entry becomes increasingly


5

complicated, since the left lane must take into account the combined gap between the

vehicles in the left and right circulating lanes. The NCHRP report notes that existing

roundabouts tend to differ regarding lane usage, both on the entry roadway and the

circulating roadway, due to localized details regarding allowed movements within the

circulatory roadway and allowed exiting movements. Thus, the report does not attempt

to develop a capacity model that simultaneously describes both entry lanes, but rather

suggests a model that can be used to calculate the capacity of the critical lane, the lane

with the highest demand. The model may be applied to either the left or right lane,

whichever experiences greater demand. Curiously, the report does not suggest a

methodology to estimate the capacity of non-critical lanes in a multi-lane approach.

Using a methodology similar to that used on the single-lane situation, the critical lane

capacity model reduces to:

ccrit = 1130*e(-0.0007vc)

where

ccrit = entry capacity of the critical lane (veh/h)

vc = conflicting circulating traffic (pcu/h).

The report suggests the following Level of Service (LOS) thresholds for roundabouts,

though it gives no guidance estimating vehicle delay, other than using existing methods

for unsignalized intersections:

Table 1. NCHRP Proposed Thresholds for Roundabouts.

Level of Service Average Control Delay (sec/veh)

A 0-10

B >10-15

C >15-25

D >25-35

E >35-50

F >50

The NCHRP report stresses the importance of considering each roundabout entry

separately when determining capacity or LOS. “Defining LOS for the intersection as a

whole is not recommended because doing so may mask an entry that is operating with

much higher delay than the others.”

The NCHRP report also placed great emphasis on the impact of roundabouts on

pedestrians and bicycles. They report that on average, 32% of motorists did not

properly yield to pedestrians waiting to cross. Motorists did not yield to pedestrians on

the entry side 23% of the time, compared to 38% of the time on the exit side. Also, if

the pedestrian started crossing from the entry side of the leg, 27% of the motorists did

not yield. However, if the crossing began on the exit side, the percentage of motorists

not yielding increased to 34%. Yield behavior also varied with the number of lanes at


6

the crosswalk. At two-lane sites, 43% of vehicles did not yield to pedestrians, compared

to 17% at one-lane sites. They also observed that 58% of the pedestrians crossing

proceeded “normally” without hesitation, while the remaining pedestrians waited to

cross until eye-contact with the conflicting motorist could be made (Transportation

Research Board 2007).

The NCHRP report observed that cyclists do not pose any significant safety hazards to

roundabout operations. They observed that 18% of all cyclists diverted off the street

onto the sidewalks. Of the remaining cyclists, 73% were positioned on the edge of the

roadway or shoulder while approaching the intersection, but 83% were observed to

“take the lane” while in the circulating roadway. The increased presence of vehicles in

the near vicinity, however, discouraged cyclists from “taking the lane.” It notes that for

cyclists, “traversing the circulating lane on the outside of the lane... is one of the most

vulnerable positions...” and refers to it as “inappropriate behavior.” The most likely

cause of a vehicle/bicycle crash, except for cyclists on the sidewalk, occurs when a

cyclists traversing the edge of the roundabout wishes to pass an exit lane and remain in

the circulating lane, but a nearby vehicle wishes to exit. These conflicts do not occur

when cyclists “take the lane.” On one occasion, however, a vehicle, apparently unhappy

about being positioned behind a bicyclist who had “taken the lane,” attempted to pass

the leading cyclist within the single-lane circulatory lane creating an unsafe situation

(Transportation Research Board 2007). Regarding bicycles, the FHWA report specifically

states, “The complexity of vehicle interactions within a roundabout leaves a cyclist

vulnerable, and for this reason, bike lanes within the circulatory roadway should never

be used” (FHWA 2000).

Another applicable observation from the NCHRP report is regarding the angle between

the legs of the intersection. “...evidence suggests that roundabouts with more than four

legs or with skewed approaches tend to have more entering-circulating crashes”

(Transportation Research Board 2007).

The FHWA guidelines are also quite thorough in discussing various types of modern

roundabouts. Of particular interest is the Urban, Single-Lane roundabout, which is

recommended for four-way intersections with an ADT of 20,000 vehicles or fewer. It

also recommends an inscribed diameter of 100 to 130 feet, also assuming four

approaches. The report gives no guidance regarding how to adjust the

recommendations or standards for intersections with more than four approaches, and

also gives little guidance regarding the maximum recommended ADT for Urban, Two-

Lane roundabouts (FHWA 2000).

The FHWA guidelines provide recommendations on when a roundabout is an

appropriate choice for an intersection. Beyond the obvious considerations, such as

available right-of-way, it provides an understanding of the traffic conditions that make

roundabouts attractive options. However, the guidelines are difficult to apply to all

locations because they assume only four approaches, and they assume that one road is

clearly a “major approach” and that one is clearly a “minor approach.” Any deviation


7

from these assumptions, and the FHWA recommendations become unclear. The

guidelines state that the percentage of left-turning vehicles is critical to determining the

effectiveness of a roundabout. A large percentage of left-turning vehicles will render a

roundabout less effective. One-lane roundabouts are recommended for sites with AADT

of 20,000–27,000, and two-lane roundabouts are recommended for sites with AADT of

40,000-52,000 (FHWA 2000).

The FHWA report states that roundabouts can often take the place of signalized

intersections. Using simulation software, the FHWA authors constructed a four-way

signal controlled intersection, and a four-way roundabout. They assumed a hypothetical

intersection that just barely met the MUTCD signal warrant thresholds. A graphic

display of the results is given in Figure 1. The results show that average delay for a

roundabout is consistently lower than the average delay of a signalized intersection.

Also, the delay at the roundabout option appears to be somewhat sensitive to the

percent of the traffic making left-hand turns.

Figure 1. Estimated Delay with Various Control Conditions. Source: FHWA Figure 3-7.

The FHWA echoes the NCHRP report in stating that the overall capacity of a roundabout

is somewhat meaningless, preferring instead capacity measures for each approach

individually. Figure 2 displays the estimated capacity of a roundabout entry as a

function of circulatory flow for several hypothetical roundabouts. As mentioned

previously, these relationships are based on regression equations using observations

from Europe and elsewhere (FHWA 2000). According to NCHRP estimates, these

relationships overestimate approach capacity. Figure 3 displays the FHWA delay model,

which is essentially the model for estimating delay at all unsignalized intersections.


8

Figure 2. Capacity of various roundabout entries. Source: FHWA Figure 4-6.

Figure 3. FHWA estimation for delay at roundabouts. Source: FHWA Figure 4-9.


9

Retting, Luttrell and Russell considered three roundabout conversions (Reno, NV,

Hutchinson, KS, and Hartford County, MD) and reported that in each of the three cases,

there was some degree of public opposition to the construction of roundabouts.

Maryland residents, many of whom have had previous experience with roundabouts in

Maryland, showed less resistance than residents in Reno and Hutchinson, who were less

likely to have encountered roundabouts. The study conducted over 1,800 phone

surveys with residents who live near the three intersections. Different samples were

questioned before and after the intersections were completed. Their results showed

that opposition to roundabouts declined significantly in all three locations after

implementation (Retting, Luttrell and Russell 2002).

Much of the previous research regarding the benefits of roundabouts has focused on

the reduction of crash rates and serious injury crashes observed at roundabouts when

compared with standard controlled intersections. For example, Persaud et al. reported

a 40 percent reduction in crash rates and an 80 percent reduction in injury crashes at 23

intersections in the United States converted into roundabouts (Persaud, et al. 2001).

Schoon and Van Minnen reported a 47 percent reduction in crashes and a 71 percent

reduction in injuries at 181 Dutch intersections converted from traffic signals or stop

signs to a roundabout (Schoon and Van Minnen 1994). Troutbeck reported a 74 percent

reduction in the rate of injury crashes after 73 intersections in Victoria, Australia, were

converted to roundabouts (Troutbeck 1993). The FHWA and TRB publications cite

similar crash reduction statistics (FHWA 2000) (Transportation Research Board 2007).

Previous studies have demonstrated that under certain conditions, roundabout

conversions can considerably improve traffic operations. Retting, Luttrell, and Russell

used panoramic video technology to observe the intersections in Kansas, and Maryland,

and Nevada (as discussed previously) and reported reductions in average vehicle delay

of 19, 23, and 13 percent, respectively. All three intersections were previously two-way

stop controlled. The three intersections had low to moderate traffic volumes and

consequently operated without significant congestion or queuing under normal

conditions. Estimated average daily traffic volumes for the Kansas, Maryland, and

Nevada sites were 12,000, 8,300, and 3,500 vehicles, respectively. Dramatic reductions

were also seen in intersection degree of saturation (56-62 percent reduction), and the

percent of stopped vehicles (48 to 57 percent reduction) (Retting, Luttrell and Russell

2002).

Some attention has been given to modern roundabout interchanges, intersections

where some of the approaches are freeway on and off-ramps. Vail, Colorado

constructed the first roundabout interchange in the U.S. in 1995 and reports a reduction

in average delay from 50 seconds/vehicle to 12 seconds/vehicle. The designers credit

flared entry and exit lanes for the observed 71 percent increase in capacity. Before the

intersection conversion, the freeway ramps and the frontage roads intersected the cross

street very near each other, resulting in awkward turning movements and dimensions

(Ourston and Hall 1997). The 128’ roundabout is similar to the Minneapolis intersection


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in that it features more than four approaches. The resulting flared-entry design, while

providing dramatic improvements in vehicle movement, is likely to prove frustrating for

pedestrians. In Maryland, another study considered the benefits of teardrop-shaped

roundabouts along I-95 at interchange locations and predicted a 94% reduction in delay

(seconds/vehicle) at this location. Again, credit for the increased capacity of the

intersection is given to the geometric flare at the entry and exit lanes (Myers 1994).

Several studies in Jordan have used regression analysis to create models for estimating

roundabout capacity and approach delay based on intersection geometry and traffic

conditions. Al-Omari, Al-Masaeid, and Al-Shawabkah used video data collection

methods to observe 14 roundabouts in Jordan for a total of 20 hours. The model

included five variables and predicted a positive relationship between the predicted

delay time and the volume of the circulating roadway, the volume of the entering

roadway, and the width of the circulating roadway. The model predicted a negative

relationship between delay time, diameter of the roundabout, and width of the entering

roadway. These results are largely intuitive and give credence to the Vail, CO,

roundabout designers who credit flared entry widths for decreasing roundabout delay.

It is not intuitive, however, why the model predicts that increasing the width of the

circulating roadway will increase delay. According to the researchers, “This is due to the

confusion caused by a larger circulating width for the drivers at the roundabout entries.

When entry drivers look for gaps in parallel streams of traffic on the circulating

roadway, they need more time to find suitable gaps and enter the roundabout” (Al-

Omari, Al-Masaeid and Al-Shawabkah 2004).

Al-Masaeid and Faddah developed a similar model for estimating roundabout capacity

in Jordan. They used regression analysis based on data collected from ten roundabouts

to develop an entry capacity model as a function of entry width, circulating width,

diameter of the center island, circulating traffic volume, and distance between the entry

and the proceeding exit (Al-Masaeid and Faddah 1997).

Hallworth considered the impacts of signalized roundabouts and reached several

applicable “rules of thumb.” First, he notes that the purpose of signaling roundabouts is

not always to increase capacity, but rather to allow authorities greater control over

traffic patterns in general. Often, roundabouts are signalized only to allow for smooth

progression of platoons in coordinated situations. Second, he notes that if space is

available, it is usually a better option to expand the roundabout, either in terms of

increasing the diameter or increasing the number of lanes, rather than add signals.

Third, he states that the effectiveness of roundabout signalization depends greatly on

the storage space within the roundabout, or in other words, the distance between the

approaches. Thus, large roundabouts have much more potential to benefit from

signalization than small roundabouts. Fourth, he argues that the optimum cycle time

should be equal to the intersection travel time under normal conditions. Fifth, he states

that the nature of roundabout signalization depends so heavily on the unique geometry

and traffic flows of the intersection that it is very difficult to prescribe specific methods

for deriving signalization plans (Hallworth 1992). Similarly, another study remarked that


11

effectively devising signalization plans for unique roundabouts is most effectively done

using software such as TRANSYT (Lines and Crabtree 1988).

A 1992 study considered the impacts of entry signals on roundabout capacity. The study

acknowledged that problems arise within roundabouts when entry flows are

unbalanced. This can result in long queues and substantial delays. The study noted that

the capacity of roundabouts is particularly affected if traffic flows are unbalanced. This

is especially the case if one entry has a very heavy flow and the entry immediately

before it has light flow, such that the heavy flow proceeds virtually uninterrupted. The

study notes that the signalization of roundabouts is likely to increase the capacity of

certain approaches, but inevitably reduces capacity on other approaches. Often, the

purpose of signals is not to reduce overall delay, but to distribute the delay more evenly

between the approaches (Shawaly, Li and Ashworth 1992).

The FHWA guidelines provide some methods that can be used to roughly estimate the

expected number of crashes at a roundabout. The accuracy of the model is in

questioned, however, because the regression was based on traffic data observed at

roundabouts in the U.K. Thus, it is uncertain how well the models will describe drivers

in the U.S. However, the general trends observed in the data are likely applicable. The

regression analysis revealed that several factors have a significant impact on

roundabout safety. The most significant factors are traffic volumes on the circulatory

and entry roadways, factors which planners and engineers have little control over.

However, according to the U.K. crash models, several physical features that were

statistically significant include entry width, circulatory width, entry path radius,

approach curvature, and the angle between entries.

The data indicates that for a roundabout with about 20,000 vehicles per day, widening

the entry roadway from one to two lanes is likely to result in a 30 percent increase in

injury crashes. In addition, the report acknowledges that the wider entry roadways add

additional safety concerns for bicyclists and pedestrians. Widening the circulatory

roadway is expected to have less of an impact on crash rates than widening the entry

roadway widths. Adding a second lane to a circulatory roadway is likely to result in a

five percent increase in the number of crashes. The report also states that maximizing

the angle between approaches will result in fewer crashes. This suggests that

roundabouts with more than the standard four approaches are expected to experience

a greater number of crashes (FHWA 2000).

3.0 CASE STUDY

The intersection of Franklin Avenue, 27th Avenue and East River Parkway is located in

the historic Prospect Park Neighborhood towards the east side of Minneapolis. It is

located just southeast of the University of Minnesota directly adjacent to the Mississippi

River Bluffs. In some ways, the intersection is rather isolated, separated from the rest of

Minneapolis to the north and east by Interstate 94, and to the south and west by the

Mississippi River. Four significant bridges are necessary to connect the area to the rest


12

of Minneapolis. Interstate 94 is located in a trench and crosses underneath East River

Parkway to the northwest, 27th Avenue to the north, and Franklin Avenue to the east.

The Franklin Avenue Bridge stretches southwest across the Mississippi River connecting

the neighborhood to South Minneapolis.

The intersection is surrounded by mix of single family homes, duplex apartments,

neighborhood businesses, a high-rise apartment building, parkland, and a hospice care

facility. While Franklin Avenue and 27th Avenue are designated Hennepin County State

Aid streets, East River Parkway is owned by the Minneapolis Park and Recreation Board,

though it is maintained by the City of Minneapolis.

Figure 4. Location of Study Area. Source: Microsoft Live Maps 2007.

The area surrounding the intersection is rich with natural resources. The Mississippi

River is located immediately adjacent to the intersection. In addition, Bridal Veil Falls is

located about 100 yards northwest of the intersection along East River Parkway. The

historic East River Parkway travels along the top of the Mississippi River Bluffs and

creates a linear parkway complete with popular bicycling and pedestrian trails that form

part of the Grand Rounds National Scenic Byway. The trails are popular locations for

exercising, scenic bicycle rides and bicycle commuting.

Study Area


13

Figure 5. Five-Way Intersection of Franklin Avenue, East River Parkway, and 27

th

Avenue SE. Bridal Veil Falls is visible. Source: Microsoft Live Maps 2007.

There are a number of unique features of this intersection directly related to its

geometry:

• The angles between the five approaches are not equal. Franklin Avenue EB and 27th

Avenue SB have been aligned so that a “through” movement from Franklin Avenue EB

will exit the intersection on 27th Avenue SB. A vehicle wishing to stay on Franklin

Avenue executes a “soft right.” This may add to the confusion of drivers who must

choose the appropriate approaching lane based on whether they wish to turn right or go

straight.

• The Franklin Avenue Bridge has two lanes in each direction with a right turn lane large

enough to hold only two vehicles. The width of the bridge prohibits lengthening the

turning lane.

• Vehicles on Franklin Avenue EB are often traveling very quickly because of the

downward grade of the bridge deck towards the intersection.

• East River Parkway SB features a bridge about 70 feet upstream from the intersection.

This bridge was constructed in 2006. During this construction, a turning lane large

enough for only 3 vehicles was constructed, and the location and width of the bridge

prohibits lengthening the turning lane.


14

• The movement from East River Parkway NB to Franklin Avenue is very sharp. Although

the turn is not specifically prohibited, only several vehicles were observed to attempt

this turn. A few were successful, while others aborted mid-movement and chose a

different route, creating an awkward and unsafe movement.

• Drivers on East River Parkway NB and Franklin Avenue WB were observed to mistake

the others’ signals for their own. On multiple occasions, Franklin Avenue WB drivers

began movement as signals turned green for the East River Parkway NB approach.

• The regional trails located along East River Parkway north and south of the intersection

results in large numbers of pedestrians crossing Franklin Avenue. The compliance with

pedestrian signalization is relatively low, and the large number of pedestrians appears

to encourage non-compliance.

• The right turn from Franklin Avenue WB onto 27th Avenue utilizes an unsignalized lane

separated from the rest of the intersection by an island.

Figure 6. Surrounding Neighborhood. Source: Microsoft Live Maps 2007.

Vehicles wishing to avoid delay at the intersection may choose to bypass the area using

Yale Avenue or Thornton Street. At first glance, these two streets appear to provide an

attractive way to bypass congestion at the five-way intersection, but the level of non-

local traffic using these routes is lower than one might initially suspect, largely due to

both the desired destinations and the nature of the streets themselves. Both of these

streets are relatively narrow (approximately 30’ curb face to curb face) and permit on-

street parking. On both streets, vehicles traveling in opposing directions must often

slow to avoid collisions, and often, one of the vehicles must pull into an adjacent parking


15

space to provide room for the other vehicle to pass. In addition, the movements for

which the local streets would provide an easy replacement are not common

movements. For example a vehicle traveling on East River Parkway SB wishing to turn

north onto 27th Avenue would likely see a lower travel time using Yale Avenue than

traveling through the five-way intersection. However this is an uncommon movement,

so the number of vehicles observed making this decision is relatively small.

Figure 7. Five-Way Intersection. Source: Microsoft Live Maps 2007.

Bicycle Facilities

East River Parkway, as mentioned earlier, has a high-quality off-street bicycle trail along

the west side and the City of Minneapolis includes the sidewalks on either side of the

Franklin Avenue Bridge as part of their bicycle facilities network. Although there are no

official on-street bicycle facilities in the area, several of the approaches have wide lanes

or narrow shoulders that can be used by bicycles. North of the intersection, for

example, bicycles traveling on East River Parkway SB often use the narrow shoulder as a

bicycle lane. The shoulder is too narrow to allow parked vehicles and it tends to vary in

width. Similar narrow shoulders can be found on Franklin Avenue WB and just north of

the five-way intersection on 27th Avenue.


16

Future Changes

Transit for Livable Communities, the recipient of $7.1 million from the Non-Motorized

Transportation Pilot Program created in 2005 as part of the Federal SAFETEA-LU bill, has

announced several projects within the study area. The non-profit organization reports

that Franklin Avenue is scheduled to be reduced from four lanes to three and will

include experimental colored bicycle lanes, and 27th Avenue is to be reduced from four

lanes to two or three to make room for bicycle lanes (Transit for Livable Communities

2007).

Previous Work

In 2004, the City of Minneapolis reached an agreement with the consulting firm URS to

design a new bridge over Bridal Veil Falls, and out of necessity considered alternatives

for the 5-way intersection. Several of the alternatives considered the feasibility of

removing the bridge altogether and closing the section of East River Parkway between

Franklin Avenue and Yale Avenue. As this would fundamentally change the traffic flow

through the area, the study also considered several alternative intersection geometries.

Several of the alternatives involved closing various sections of East River Parkway, both

north and south of Franklin Avenue, leaving an intersection with 4 approaches. Several

possible alternative routes for the displaced traffic were considered.

URS also held four public meetings to present the results of the study and receive

feedback from the community. The report states that the community had “mixed

feelings” regarding options that would redirect traffic and close one of the five

approaches. Community members stated that they viewed East River Parkway as an

important historic resource and would prefer alternatives that left the five-way

intersection intact. As a result, URS also considered two additional options: a one-lane

roundabout, and a two-lane roundabout (URS 2004).

The URS report concluded that a one-lane intersection would not provide adequate

capacity during morning and peak hours, but that a two-lane roundabout would be

sufficient. The scope of the URS report was somewhat limited, however. A detailed

microsimulation was not within the scope of the study, and intersection performance

measures were not given in any detail. Without questioning the overall results of the

URS report, this report attempts to gain a more detailed understanding of these two

alternatives as well as consider additional, similar alternatives.

4.0 DATA COLLECTION

There are two primary sources of 15 minute turning movement data used in the

completion of this report. The City of Minneapolis Public Works Department performed

a turning movement study spread across two days. The PM data was collected on

9/21/2007 (Friday), and the AM data was collected on 9/27/2007 (Thursday). In

addition, I collected data over the course of four days. I collected AM data on

9/25/2007 (Tuesday), and PM data on 9/6/2007 (Thursday), 9/13/2007 (Thursday), and


17

9/25/2007 (Tuesday). Neither the data I collected, nor the data collected by the City of

Minneapolis provide a complete data set from 6:00 AM to 10:00 PM. Both turning

movement counts were performed using the same methodology. Figure 8 depicts the

two data sets collected and the averaged combination of the two. In cases were one

data set was incomplete, the data from the other set was used, where both data sets

had collected values, the two were averaged, and where neither had values, the average

of the time intervals before and after the missing interval was used.

Figure 8. Two Primary Data Sets and the Combined Average.

The Minneapolis data collection, however, did not include counts of trucks, buses,

pedestrians, or cyclists. I collected data regarding these users periodically during Early

October. Figure 9 displays the combined truck/bus, pedestrian, and bicycle counts. For

the purposes of this study, cyclists riding on the sidewalk or on the East River Parkway

trail are considered pedestrians.


18

Figure 9. Bicycle, Pedestrian & Truck/Bus volumes.

A critical aspect of the traffic flow through the intersection is the highly directional

nature of peak hour volumes. Traffic characteristics observed during the AM peak hour

are significantly different than the characteristics observed during the PM peak hour.

Figure 10 displays the approach volumes from 6:00 AM to 10:00 PM. Notice that the

East River Parkway NB and East River Parkway SB approaches peak only in the AM and

PM, respectively, but not both. This directional flow is likely due to the close proximity

to the University of Minnesota and represents large numbers of students, faculty, and

staff traveling to and from campus.

Figures 11 and 12 depict each turning movement along with the AM and PM Peak Hour

Volumes. Notice that the sharp right turn movement from East River Parkway NB onto

Franklin Avenue and the sharp left turn from Franklin Avenue WB onto East River

Parkway are zero. While I observed fewer than half a dozen vehicles attempting either

of these movements during the data collection period, the Minneapolis data did not

include these movements. It was also observed that the drivers making these

movements appeared to be lost. Indeed, it is unlikely for drivers to attempt this

movement unless they are lost. This study assumes that no drivers attempt either of

these movements.


19

Figure 10. Vehicle approach volumes.

Figure 11. AM Peak Hour Volumes (veh/h).


20

Figure 12. PM Peak Hour Volumes (veh/h).

Figure 13 displays the peak hour pedestrian volumes. The pedestrian volumes are also

somewhat directional in a similar manner to the vehicle volumes, but not to the same

extent. The peak hour pedestrian volumes shown here represent the PM peak hour.

Figure 13. Peak Hour Pedestrian Volumes (peds/h).


21

In addition to collecting data at the five-way intersection, data was also collected

regarding traffic flows on portions of Yale Avenue and Thornton Street between 3:30

and 5:30 PM. The purpose of these counts is to estimate the level of traffic attempting

to avoid delays at the five-way intersection by using local streets as through streets.

Traffic volumes on Yale Avenue were counted at the intersection of 27th Avenue and

Yale Avenue on 9/25/2006 (Tuesday), and traffic volumes on Thornton Street were

counted at the intersection of Thornton Street and East River Parkway on 9/26/2007

(Wednesday). Table 2 displays the 15 minute traffic volumes collected.

Table 2. Observed Traffic Volumes on Local Streets.

Thornton Street

(South of Franklin

Avenue)

Yale Avenue (East of

27th Avenue)

Yale Avenue (West of

27th Avenue)

TIME NB SB WB EB WB EB

15:30 7 3 5 11 3 8

15:45 6 5 3 9 1 4

16:00 5 9 7 11 3 5

16:15 3 7 7 9 7 7

16:30 7 16 6 21 4 4

16:45 9 19 20 34 12 10

17:00 6 15 17 30 4 11

17:15 8 10 18 24 6 8

17:30 9 14 20 20 6 9

17:45 6 12 15 18 7 7

18:00 3 12 12 12 6 7

18:15 5 8 10 9 7 4

5.0 MICROSIMULATION MODEL

AIMSUN NG (Advanced Interactive Microscopic Simulator for Urban and

Non-Urban Networks) was used to create a microsimulation of the five-way

intersection, as well as one intersection in each direction, except for across the Franklin

Avenue Bridge. The model contained Yale Avenue and Thornton Street, although

Superior Street was excluded to simplify the model. Any number of microsimulation

tools would have been appropriate for this study. AIMSUN was chosen because of its

convenient availability and the authors’ previous experience with this particular

software package.

AIMSUN follows a microscopic simulation approach. The behavior of each vehicle in the

network is continuously modeled throughout the simulation time period while it travels

through the traffic network. AIMSUN is a combined discrete/continuous simulator.

Some elements of the system, such as vehicles or detectors, change state continuously

over time. Other elements, such as traffic signals or entrance points, change state


22

discretely at specific times. AIMSUN models the behavior of vehicles according to basic

car following, gap acceptance, and lane changing models.

During each time simulation step (0.75 seconds), AIMSUN first applies a lane-changing

model. This simulation assumes that all vehicles are very familiar with the area and

allows drivers to know which lane they need to be in up to 5 road segments ahead. The

lane-changing model used by AIMSUN can be considered a development of the Gipps

lane-changing model (Gipps 1986). Lane changes are modeled as a decision process,

analyzing the necessity of the lane change (such as for turning maneuvers determined

by the route), the desirability of the lane change (to reach the desired speed when the

leading vehicle is slower, for example), and the feasibility of the lane change (TSS 2006).

To determine if a lane change is possible, AIMSUN employs a gap-acceptance model.

The gap-acceptance model determines the feasibility of a lane change by calculating the

required size gap between vehicles and determining if the vehicle is appropriately

aligned with the gap. Next, the model determines the impact of entering the gap on the

vehicles in front of and behind the gap to determine if acceptable braking distances will

be kept for all three vehicles and the deceleration imposed on the vehicle behind the

gap. If all conditions are appropriate, the vehicle is allowed to accept the gap and

change lanes (TSS 2006).

After applying the lane changing model, or for vehicles who do not wish to change lanes,

AIMSUN uses a car-following model. The car-following model implemented in AIMSUN

is based on the Gipps model. It can be considered an ad hoc development of the Gipps

empirical model (Gipps 1981), in which the model parameters are not global, but

determined by the influence of local parameters depending on the “type of driver”

(speed limit acceptance of the vehicle), the geometry of the section (speed limit on the

section, speed limits on turnings, etc.), the influence of vehicles on adjacent lanes, and

other local and vehicle parameters. The car-following model balances the desired speed

of an individual vehicle with the maximum possible speed imposed on the vehicle by the

vehicle directly in front of it. AIMSUN first calculates the speed a vehicle would travel if

there were no leading vehicle. Then it calculates the maximum possible speed the

vehicle can obtain and still remain a safe distance from the leading vehicle. The actual

speed obtained is the lesser of the two (TSS 2006).

The model featured four vehicle types, cars, trucks/buses, pedestrians, and bicycles.

Vehicles were assumed to exhibit exponential arrival patterns. The mean arrival

headway is calculated as (1/λ), where λ is the arrival rate in veh/s. The arrival headway

distribution is then calculated as t=(1/λ)*(ln(u)), where u is a random number between 0

and 1.

The model featured a dynamic, logit-based route choice algorithm that used travel time

as the path cost. The path cost was updated every 15 minutes. Given the route

limitations imposed on the model (discussed later in this section) and the small size of

the network, each vehicle has only two available routes to choose from. The shortest


23

path algorithm is a variation of Dijkstra's label-setting algorithm (Dijkstra 1959) and it

provides the shortest path tree for each destination. Thus, AIMSUN calculates the

shortest path from the start of every section to one destination (TSS 2006).

Traffic demand was entered using 15 minute Origin/Destination (O/D) Matrices. The

base matrices were created using the collected data. Between 3:30 PM and 6:00 PM,

the traffic volumes collected at the two secondary intersections were added to the base

O/D matrices after making assumptions about the vehicles origins and destinations

using observed turning counts.

The model assumes that vehicles either diverted around the five-way intersection or

traveled through it. The model did not allow vehicles to both use a local street and pass

through the five-way intersection. For example, a vehicle entering the system on East

River Parkway SB that wishes to exit traveling east on Franklin Avenue may either use

Yale Avenue and Thornton Street to bypass the five-way intersection or the vehicle may

travel through the five-way intersection directly from East River Parkway to Franklin

Avenue. The vehicle would not be permitted to use Yale Avenue between East River

Parkway and 27th Avenue, turn south onto 27th Avenue and then pass through the five-

way intersection making a left turn onto Franklin Avenue. Similarly, the vehicle would

not be permitted to travel through the five-way intersection from East River Parkway SB

continuing south on East River Parkway, then diverting north on Thornton Street to

reach Franklin Avenue.

The inclusion of on-street bicycles in the model was a challenging task. Most of the

cyclists do not currently “take the lane,” instead riding as far to the right of the roadway

as possible. In most cases, the lanes are wide enough that cars and bicycles can easily

share horizontal space within a lane without causing delay on each other. AIMSUN,

however, does not permit two vehicles to share horizontal space within a lane, so a set

of bicycle-specific roadways were created next to the automobile roadways, virtually

assuming that there is no interaction between bicycles and cars. This assumption is not

entirely reasonable, but not entirely unreasonable, either. In general, cars and bicycles

are able to share the lanes without causing significant delay on each other, except at key

decision points. Consider, for example, a cyclist who wishes to make a left hand turn

from the left lane of a two-lane roadway. At some point, the cyclist must move from

the far-right side of the road to the far-left side of the roadway, passing through the

vehicle paths. Figure 14 displays how these decision points are handled in the model.

Once in the five-way intersection, the bicycles often made movements that did not

easily correspond with legal movements. For example, many cyclists, when passing

through the five-way intersection, may begin from a vehicle lane, but may choose to

ride onto the sidewalk on the other side of the intersection rather than continue in a

vehicle lane. In these situations, I assigned cyclists to the movement most similar to the

one observed.


24

Figure 14. Bicycle Decision Point and Bicycle Lanes.

6.0 MODEL VALIDATION

Validation of the model can be demonstrated using a comparison of vehicle queue size

individually for an individual link approaching the 5-way intersection. Queue size is an

appropriate measure for use in model validation because it demonstrates the accuracy

of the traffic signal in allowing a realistic number of vehicles to pass through the 5-way

intersection during each cycle. The relatively small size of the network represented in

the model leaves little room for model adjustment. The only element of the network

that causes significant delay is the traffic signal at the 5-way intersection, which is

constant in terms of traffic operations. The number of cars progressing through the

intersection from each approach is essentially related only to the portion of the queue

progressing through the intersection during each cycle.

The relationship between vehicle delay at an intersection and queue length has been

the subject of several past studies. Researchers such as Heidemann, Webster, Meissl,

and Newell have all explored various aspects of delay-queue size relationships. Each

study has made different assumptions regarding the type of signalization used and the

arrival patterns of the vehicles. Heidemann establishes the relationship between the

probability generating function of the queue length and the Laplace-transform of the

delay distribution (Heidemann 1994).

The relationship between queue size and average delay can be demonstrated using the

AIMSUN simulation model. Figures 15 and 16 and Table 3 demonstrate this relationship.

The data is obtained by averaging the results of five replications of the model. The data

shown represents the delay and queue sizes simulated on the Franklin Avenue EB

approach to the intersection. A similar exercised performed on the other four

approaches would yield similar results. Figure 15 demonstrates the relationship

between delay and queue size through time, while Figure 16 removes the element of


25

time and uses a trend line to estimate the relationship. Table 3 shows the correlation

between mean delay, mean queue size, and maximum queue size.

Figure 15. Franklin Avenue EB Delay and Queuing Characteristics.

Figure 16. Simulated Relationship Between Mean Delay and Maximum Queue Size.


26

Table 3. Correlation of Delay and Queue Size.

Mean Delay Mean Queue Size Max Queue Size

Mean Delay 1

Mean Queue Size 0.8968 1

Max Queue Size 0.8270 0.9703 1

The accuracy of the three highest-PM-volume approaches in the five-way intersection is

demonstrated by comparing the observed instantaneous queue sizes at the beginning of

each green phase for each approach with the queue sizes estimated by the model. The

maximum queue sizes for the Franklin Avenue EB approach were observed on

10/24/2007 (Tuesday) and 11/5/2007 (Monday). The maximum queue sizes for the

Franklin Avenue WB approach were observed on 10/26/2007 (Thursday) and 11/5/2007

(Monday). The maximum queue sizes for the East River Parkway SB approach were

observed on 10/25/2007 (Wednesday) and 11/7/2007 (Wednesday). On each day, the

queues were observed from 3:30 PM to 6:00 PM. For each approach, the instantaneous

queue size was recorded as the approach entered a green signal phase throughout the

2.5 hour period.

Maximum queue sizes for each 4 minute interval (an approximation of the average cycle

length during the most congested period) were obtained from AIMSUN for 30

replications for the time period of 3:30 PM to 6:00 PM and compared with the observed

maximum queue sizes during this same time. There are two challenges with this

methodology that should be noted. First, for any portion of the 2.5 hour validation

period where the cycle length is shorter than 4 minute, if two cycles occur within the 4

minute period, AIMSUN will record only the larger value, whereas in the observed data,

both would be recorded. Thus, the maximum queue sizes recorded by AIMSUN may

omit small, but reasonable maximum queue sizes. Second, I assumed that the

maximum queue size on a link occurred at the moment each green phase began. While

this is a reasonable assumption during uncongested times, it is not as straight-forward

during times of congestion, especially in situations where the full queue does not pass

through the intersection during a single phase. If a queue experiences a larger arrival

rate than departure rate during any portion of the green phase, I may not have captured

the real maximum queue size. Figures 17, 18, and 19 show the observed maximum

queue lengths, the results of the 30 replications, and the average of the 30 replications.

The validation process involved adjusting the vehicle parameters, arrival rates, and

route choice models such that the observed data was contained within the range

simulated by the 30 replications. The two sets of observed queue sizes for each

approach demonstrate high variability of traffic conditions that can be observed at this

intersection on different days. Compare, for example, the difference between the

observed data sets on the Franklin Avenue EB and the East River Parkway SB approaches


27

between 5:15 PM and 5:30 PM. It is difficult to introduce large amounts of variation at

one point in the model, without also introducing it at other points. While additional

spread in the 30 replications would more accurately represent the conditions on

Franklin Avenue EB at 5:15 PM, this need had to be balanced with a desire for less

variation on the same approach at, say, 5:45 PM.

Figure 17. Franklin Avenue EB Approach Validation.


28

Figure 18. Franklin Avenue WB Approach Validation.

Figure 19. East River Parkway SB Approach Validation.


29

Table 4 displays a statistical evaluation of the validation process for each of the three

approaches considered. The tests involve two samples. The first sample includes all

maximum queue sizes at four minute intervals from all 30 replications for a total of 1140

observations. The second sample represents all observed maximum queue sizes

including both days observation for a total of 89-92 observations for each approach. A

t-test for unequal variances is first used to test the null hypothesis that the difference

between the means of the two samples is zero. As the table shows, the calculated t

values range from 0.2345 to 0.5106. Since t is substantially lower than about 2.0, the

null hypothesis cannot be accepted, indicating that the difference between the means is

statistically significant. A t-test may set an unrealistic expectation of similarity,

however, so a z-score provides additional insight regarding the difference between the

means of the two samples. Since all three z-scores are less than .5, the means of the

simulated maximum queue lengths are within 0.5 standard deviations of the means of

the observed data.

Table 4. Statistical Tests of for 3 Approaches.

Average of

30

Replications

Observed

Data

East

River

Parkway

SB

count 1140.00 89

average 30.1 25.7

stdev 12.9 14.1

variance 166.7 199.6

t 0.2345

z-score 0.3093

Franklin

Avenue

EB

count 1140.00 89

average 27.2 31.0

stdev 7.6 11.7

variance 58.0 136.2

t 0.5106

z-score -0.3214

Franklin

Avenue

WB

count 1140.00 92

average 23.9 20.2

stdev 8.4 8.0

variance 70.9 63.4

t 0.4848

z-score 0.4642

The validation of this model could be significantly improved if additional field data were

obtained. This model utilizes traffic demand data averaged from across two days, and

compares it to the queue sizes observed on two different days. This methodology does

not include any measures for ensuring that the traffic demand in the model corresponds


30

with the observed queue sizes. The model assumes that all traffic observations

represent “average” days. Additional field data would provide additional insight

regarding the accuracy of the model and would provide additional confidence that the

observed data represented the “average” day. Additional queue size data at other

times of the day (not during peak hours) could provide additional insight as well. It is

likely that observed queue sizes would be less erratic during mid-day than during peak

hours. It would be beneficial to know how accurately the model represented the actual

traffic conditions throughout the rest of the day. Finally, the model has only undergone

validation measures regarding automobile traffic. While this is reasonable, given that

most of the cumulative delay at this intersection is inflicted on automobiles, it would be

beneficial to understand quantitatively how well the model represented pedestrians

and bicycles.

During validation and the alternatives analysis, the average of 30 replications is used to

compare measures of effectiveness. Toledo et al illustrate a common method for

determining the appropriate number of replications to be performed, given an initial

guess of the measures of effectiveness (Toledo, et al. 2003). Table 5 uses this

methodology to demonstrate the number of replications required to confidently predict

delay time on each approach after making several assumptions. The analysis assumes

as 95% level of significance is required and that a 5% error of the estimate is acceptable.

Since each of the five approaches demonstrates surprisingly different traffic volumes,

the number of required replications is calculated separately for each approach. For all

approaches except East River Parkway SB, ten or fewer replications are sufficient to

meet the assumed requirements. The East River Parkway SB approach, however

requires 28 replications to confidently predict delay time. This is consistent with Figure

19, however, which shows that traffic on the East River Parkway SB approach appears to

vary to a greater extent than the other approaches.

Table 5. Required Number of Replications.

Approach Standard

Deviation

Delay

Time

(s/veh)

Level of

Significance

Percentage

Error of the

Estimate

Number of

Required

Replications

Franklin Avenue EB 3 65 95% 5% 3.6

Franklin Avenue WB 2 73 95% 5% 1.3

East River Parkway SB 11 85 95% 5% 28.0

East River Parkway NB 6 81 95% 5% 9.2

27th Avenue SB 2 60 95% 5% 1.9

7.0 ALTERNATIVES ANALYSIS

This report considers the effectiveness of seven alternatives for this intersection. Each

scenario builds off the previous scenario, and relies on the results of the previous


31

scenario for its justification. After all seven scenarios have been presented, a

comparative analysis will be presented. The seven scenarios considered are:

• Scenario 1: Do Nothing/Existing Conditions

• Scenario 2: Allow Non-Conflicting Movements

• Scenarios 3a and 3b: One-Lane Roundabout

• Scenario 4: One-Lane Roundabout, Pedestrian Signals, Slip Lane

• Scenarios 5a and 5b: Two-Lane Roundabout

• Scenario 6: Two-Lane Roundabout, Pedestrian Signals

• Scenario 7: Two-Lane Roundabout, Single Lane Exits, Flared-Width Entries, Slip Lane

Scenario 1 – Do Nothing

This alternative retains the intersection as is without any modification. It is presented

here as a basis of comparison for the other alternatives.

Existing Signalization

The signal operates on an actuated cycle with 5 phases, four vehicle phases and one

pedestrian phase. The first phase provides a green signal for the Franklin Avenue EB

and the 27th Avenue SB approaches, which have been aligned to act as opposing

approaches. The second phase provides exclusive green to East River Parkway NB, the

third phase to East River Parkway SB, and the fourth phase to Franklin Avenue WB.

Pedestrians are prohibited during the other four phases, and the 30 second pedestrian

phase only occurs if the walk button is pressed. The four vehicle phases occur in a fixed

sequence, each with a minimum of 10 seconds green time, extendible to 60 seconds per

phase. Each approach has vehicle detectors located within 15 feet of the stop line, and

the light will continue to stay green until either the length between vehicle detection is

greater than three seconds or the 60 second maximum has been reached. For all

phases, there are 3 seconds of yellow, and 3 seconds of all red time.

The resulting cycle length varies significantly depending on current conditions. If no

vehicles or pedestrians are present, the minimum cycle length is 64 seconds. If each

phase is extended to the maximum 60 seconds, and the pedestrian phase is triggered,

the cycle will reach the maximum 300 seconds (5 minutes). While this rarely happens in

practice, cycle lengths at or above four minutes are common during the evening peak

hour. Figure 20 graphically displays the existing phase sequencing.

Figure 20. Existing Phase Sequencing.


32

Scenario 2 – Allow Protected Movements

Currently, right turns on red are prohibited. Because the intersection has 5 approaches,

allowing right turn on red could lead to safety concerns, and the potential benefits may

not be significant. Of course, the right turn from Franklin Avenue WB to 27th Avenue NB

is always allowed because of the unique geometry of the island, but this movement is

uncommon. In addition, the movement from East River Parkway NB to Franklin Avenue

EB is extremely sharp and also uncommon. The movement from 27th Avenue SB to East

River Parkway NB is also quite uncommon, so there are only two movements that could

benefit from right turns on red, but both of these movements have challenges

associated with them as well. The right turn from East River Parkway SB to Franklin

Avenue WB is a common movement, and the intersection could benefit significantly by

allowing right-on-red, but the turning bay is only long enough to accommodate three

vehicles. It is likely that if this movement were allowed the benefits would be minimal

unless the turning bay was lengthened. Lengthening the turning bay might be difficult

given the bridge over Bridal Veil Falls immediately upstream from the intersection and it

is likely that residents would not favor removing parkland to construct the new lane.

Finally, the right turn movement from Franklin Avenue EB is the most promising

candidate for a right-on-red option, but it also has several challenges. It would be

difficult to specify which right turn movement was allowed on which red signals.

Remember that the right turn lane on Franklin Avenue EB allows turns onto both

Franklin Avenue EB and East River Parkway SB. While allowing the movement onto East

River Parkway could probably be allowed at all times, it is likely that drivers would also

try to turn right onto Franklin Ave, which would require crossing multiple traffic lanes

and is a potential safety hazard. For these reasons, a right-on-red option was not

considered.

Scenario 2 considers a protected signalized right turn from Franklin Avenue EB onto

both Franklin Ave and East River Parkway during the 4th phase of the signal cycle, while

Franklin Avenue WB has green time. Assuming no vehicles from Franklin Avenue WB

want to make the sharp left to travel south on East River Parkway, vehicles turning right

from Franklin Ave EB don’t cross any traffic lanes. Phase 3 allows the protected right

turn from 27th Avenue SB to East River Parkway, though this movement is uncommon.

In addition, several protected pedestrian movements have been allowed. Phase 2

allows Pedestrians to cross the eastern Franklin Avenue approach, and Phase 4 allows

pedestrians are allowed to cross 27th Avenue. Figure 21 graphically displays the phase

sequencing used in Scenario 2.

Figure 21. Scenario 2 Phase Sequencing.


33

The effectiveness of this scenario would require more than simply altering the signal,

however. Since the right turn lane on Franklin Avenue EB is long enough to hold only 2

cars, this Scenario assumes that drivers wishing to make a “through” movement to 27th

Avenue can be convinced to use the left lane on Franklin Avenue. Currently, the lane

utilization on Franklin Avenue EB is unbalanced. Vehicles wishing to turn left typically

utilize the left lane (74 during the PM peak hour), while vehicles wishing to proceed

through or turn right typically utilize the right lane (807 during the PM peak hour). This

disproportionate lane usage often results in large queues in the right lane with virtually

no queue in the left lane. Scenario 2 assumes that signage and striping will effectively

convince most drivers wishing to make “through” movements to use the left lane

allowing right-turners to fully utilize the right lane, and is valid only if re-striping can

guarantee that “through” vehicles do not become stuck behind vehicles making left-turn

movements.

Scenarios 3a and 3b – One Lane Roundabout

Scenarios 3a and 3b both consider a one lane roundabout. The Federal Highway

Administration (FHWA) recommends a minimum of 100 to 130 feet diameter for single

lane, urban roundabouts with four approaches. The roundabout considered in this

alternative is 150 feet in diameter to accommodate the unique 5-way geometry. This

dimension includes the 15 foot circulating lane, as recommended by the FHWA

guidelines.

Figure 22. Geometry for Scenarios 3a and 3b.

Pedestrian crossings occur 50 feet from the yield line on all five approaches, and

pedestrian islands are provided on all approaches but East River Parkway NB due to

constrictive geometry and low pedestrian volumes. Although a detailed geometric

design was not completed, it appears that a single-lane roundabout will easily fit within


34

the existing right-of-way used for the street network. Eminent Domain should not be

required to construct this roundabout.

Neither scenario provides on-street bicycle facilities and both scenarios assume that

cyclists “take” the entire traffic lane to traverse the roundabout. It is assumed that

cyclists will merge from the far-right side of the road to the center of the lane 50 feet

from the roundabout yield line.

Scenarios 3a and 3b differ in the treatment of pedestrian right-of-way. Scenario 3a

assumes that all automobiles immediately yield to pedestrians. While in accordance

with Minnesota state statutes, it is probably an unrealistic assumption. Scenario 3b

assumes that all pedestrians yield to automobiles and wait for an appropriate gap to

cross. This is also an unrealistic assumption because not all pedestrians will yield, and

many automobile drivers will choose to follow state statutes and yield to pedestrians.

In the case of an unsignalized roundabout, it is likely that the probable outcome will be

somewhere between these two scenarios.

Figures 23 and 24 display the demand based on the observed volumes from Scenario 1.

These represent the flow expected if there was no queuing. It should be recognized

that roundabout is expected to experience unbalanced flow. Notice in the AM Peak

hour that expected demand on one portion of the circulating roadway is 1336 veh/h

while another portion is only 81 veh/h. Such unbalanced entry and exit volumes often

have unexpected queuing results. Adopting the NCHRP recommended equations and

assumptions for determining the entry capacity of each approach, it seems unlikely that

a single-lane roundabout will accommodate this demand without queuing. Table 6

displays an initial analysis of approach capacity during the PM Peak Hour. This analysis

does not take into account the unbalanced nature of expected traffic flows, however,

and is useful only insofar as it points out that the expected demand is not likely to be

accommodated. The unbalanced entry and exit flows are likely to give some entries

priority over others, resulting in unexpected queues. Also, recall that the NCHRP

capacity equations produce significantly lower capacity estimates than the FHWA

estimates.


35

Figure 23. Roundabout AM Peak Hour Demand.

Figure 24. Roundabout PM Peak Hour Demand.


36

Table 6. Initial Capacity Analysis based on NCHRP equation. All figures are veh/h.

Approach Entering

Demand

Circulating

Volume

Calculated

Capacity

Unmet

Demand

AM Peak Hour

Franklin Avenue WB 569 81 1042

Franklin Avenue EB 427 988 421 6

East River Parkway SB 131 684 570

East River Parkway NB 649 570 639 10

27th

Avenue SB 139 1197 341

PM Peak Hour

Franklin Avenue WB 881 435 731 150

Franklin Avenue EB 486 581 632

East River Parkway SB 625 856 480 145

East River Parkway NB 215 854 481

27th

Avenue SB 313 752 533

Scenario 4 – One Lane Roundabout, Pedestrian Signals, Slip Lane

After reviewing the preliminary results of Scenario 3, it is clear that a single lane

roundabout is unable to handle peak hour volumes, especially the queuing on the East

River Parkway SB approach. Scenario 4 is a direct response to the results of Scenario 3

and attempts to provide relief to East River Parkway SB approach. Scenario 4 provides a

“slip lane” that will allow vehicles turning right from East River Parkway SB onto Franklin

Avenue to bypass the roundabout. This lane can be constructed within existing right-of-

way.

Figure 25. Scenario 4 geometry.


37

Recognizing the large numbers of pedestrians, especially those wishing to cross the

western approach of Franklin Avenue, it may be prudent to provide pedestrian crossing

signals. Scenario 4 assumes that pedestrian signals are installed at all crossings. The

signals give immediate priority to pedestrians. Upon arrival at an intersection, a

pedestrian pushes a pedestrian button at which time the cross traffic receives a 3

second yellow phase followed by 2 seconds of red. Pedestrians are then given 7

seconds to cross, after which vehicles experience an addition 2 more seconds of red

before receiving a minimum of 30 seconds green time. Pedestrians arriving within the

minimum 30 seconds of green must wait until the end of the green phase to cross.

Approaches featuring a center pedestrian median are considered separate intersections.

Thus, to fully cross one approach, a pedestrian must push two buttons, one before

crossing the first lane, and a second on the pedestrian island.

Potentially, this system of pedestrian crossings could result in unfortunate levels of

pedestrian delay if a pedestrian had to wait through the full 30 second automobile

phase twice to cross a single approach. However, considering entry and exit lane pairs

as a single intersection has drawbacks as well. Vehicles stopped within the exit lanes

potentially block circulating traffic, effectively stopping all vehicle traffic at the

intersection. If the pedestrian cycle was lengthened to allow a pedestrian to cross both

the entry and exit lanes as well as the center median, the likelihood of circulatory traffic

being stopped is greatly increased. There are several options that could be considered

to mitigate this situation that have not been modeled. The pedestrian signals could be

coordinated such that after a pedestrian pushes the button, both lanes do not

immediately enter a pedestrian phase, but instead, each lane enters a pedestrian signal

based on when the pedestrian is expected to arrive at that crossing. Alternatively,

buttons pushed from the center medians could be exempt from waiting through the full

30 second automobile phase. A third option could allow pedestrians crossing from the

exiting lane side to cross in a single phase, but continue to require pedestrians crossing

from the entering lane side to cross during two phases. However, it is unlikely that a

pedestrian will be expected to wait through two full automobile cycles.


38

Figure 26. Expected AM Peak Hour Demand.

Figure 27. Expected PM Peak Hour Demand.

Using the NCHRP equation to estimate entry capacity, the expected East River Parkway

SB approach capacity would remain unchanged at 480 veh/h. With the addition of the

“slip lane,” the new expected demand is only 416 veh/h, so ignoring the effects of

unbalanced entry and exit flows, queuing would not be expected on East River Parkway

SB in Scenario 4.

Scenarios 5a and 5b – Two Lane Roundabout

Scenarios 5a and 5b are similar to scenarios 3a and 3b, except that the circulating

roadway and all entry and exit lanes are two lanes. The inscribed diameter, including

the width of the 24’ circulatory roadway remains at 150’. Indeed, the additional space


39

required to accommodate two entry and exit lanes from each approach may be difficult

to accommodate within the existing right of way.

Though not much (if any) additional land would be required to construct a two lane

roundabout, there are several possible modifications to this design that could minimize

the land taken. For example, not all entries and exits necessarily need to be two lanes.

27th Avenue, for example, could likely be reduced to one lane in each direction. In

addition, it is not immediately clear from the literature that the roundabout should be

perfectly circular. The unique shape of the existing right of way would lend itself nicely

to an elliptical roundabout. Neither the FHWA guidelines nor the NCHRP report give any

guidance regarding non-circular roundabouts. Certainly there are examples of large

traffic circles that are not exactly circular, however, I am unaware of any examples of

roundabouts of this approximate size that are not circular, and existing literature does

not appear to address the subject.

There are many different ways in which entering and exiting vehicles can be assigned to

utilize entry and exit lanes. In Scenarios 5a and 5b, both circulating lanes are permitted

to exit at each exiting junction, but only vehicles in the inside lane of the roundabout are

permitted to proceed past an exit without exiting.

It should be recognized that there is no time during which a full two-lane roundabout

would be required. For example, during the AM peak period, two lanes would only be

required between the East River Parkway NB entrance and the opposite exit to East

River Parkway. The rest of the roundabout would likely be served well by a single lane.

Likewise, during the PM peak, two lanes may only be required between the East River

Parkway SB approach and the opposite exit to East River Parkway or Franklin Avenue.

However, to meet the directional nature of the traffic demands during AM and PM peak

hours, Scenario 5 expands the full roundabout to two lanes.

Similar to Scenarios 3a and 3b, Scenario 5a assumes that all vehicles yield to

pedestrians, and Scenario 5b assumes that all pedestrians yield to vehicles.


40


Scenario 6 – Two Lane Roundabout, Pedestrian Signals

Scenario 6 is identical to scenario 5 in geometry. The pedestrian signals described in

Scenario 4 have been added.

Scenario 7 – Two Lane Roundabout, Single Exit Lanes, Flared Entry Lanes, Slip Lane

Scenario 7 estimates the ability of flared entry lanes to increase the entry capacity of

approach lanes on a two lane roundabout. In this scenario, all exit roadways are one

lane, and all approaches begin with one lane and flare to two lanes about 30’ before

meeting the two-lane roundabout. In addition all pedestrian crossings are one lane

wide, so pedestrian signals are not used and all automobiles are assumed to stop for all

pedestrians. The “slip lane” from scenario 4 has been added to this scenario.

It should be noted that the necessity of striped lanes within a roundabout is not always

prevalent in the literature, including the FHWA and NCHRP guidelines. For example, the

FHWA guidelines discuss flared roadways to accommodate multiple lanes, but never

explicitly state that the number of lanes in the flared roadway should match the number

of lanes in the circulatory roadway. Indeed, the guidelines only go so far as to state

when flared entry lanes are used, the circulating lane width should be “increased

accordingly,” which may or may not be interpreted to include striping multiple lanes.

Certainly in other nations, wide roundabouts with space for multiple lanes remain

unstriped. AIMSUN, however, does not permit two vehicles to share horizontal space

within a single traffic lane. While in reality, the circulating roadway and entry lane flares

may be thought of only in terms of width, AIMSUN and other simulation tools must


41

model in terms of “number of lanes.” So, while the entry lanes in this scenario are

expanded to two 12’ entry lanes, if left unstriped, the 24’ could potentially

accommodate three vehicles at the yield line. The potential impacts of this on the

results are left unknown.


8.0 MEASURE OF EFFECTIVENESS - DELAY

Figure 30 and Tables 7 and 8 display the overall results from the seven scenarios. In

terms of average intersection delay, Scenario 2 is generally only a small improvement

over Scenario 1. It becomes clear that all of the roundabout options remove nearly all

of the delay during non-peak hours. All approaches are estimated to operate at LOS A

during non-peak hours. However the roundabout options differ greatly during peak

hours, especially the PM Peak hour. Considering only mean delay of each Scenario as a

whole doesn’t tell the whole story. To gain a full understanding of each Scenario, delay

from each approach must be considered individually. Figures 30-39 display the

individual approach delays for each scenario.


42

Figure 30. Comparison of Mean Delay for all Scenarios.

Table 7. 15-Minute Average and Maximum 15-Minute Average Delay (s/veh).

SCENARIO 1 2 3a 3b 4 5a 5b 6 7

Average Vehicle Delay 72 66 16 9 9 3 2 4 5

Maximum Average Vehicle Delay 122 108 116 48 34 5 4 7 13

Average Franklin Avenue EB Delay 65 48 4 2 5 3 2 4 3

Average Franklin Avenue WB Delay 73 72 9 9 10 3 3 3 6

Average East River Parkway SB Delay 85 88 61 28 20 5 5 6 9

Average East River Parkway NB Delay 81 81 13 12 13 3 2 3 9

Average 27th Avenue SB Delay 60 60 6 5 6 1 1 1 2

Max Average Franklin Avenue EB Delay 118 89 10 8 14 6 4 8 8

Max Average Franklin Avenue WB Delay 105 100 64 67 64 8 7 9 24

Max Average East River Parkway SB Delay 197 195 421 183 110 10 9 12 28

Max Average East River Parkway NB Delay 156 142 129 105 130 8 8 9 45

Max Average 27th Avenue SB Delay 87 81 19 16 20 2 2 3 7

Average Pedestrian Delay 64 63 1 7 16 1 3 14 1

Maximum Average Pedestrian Delay 99 97 5 19 26 1 7 23 1

Average Bicycle Delay 52 50 3 1 1 1 1 1 4

Maximum Average Bicycle Delay 92 83 12 12 14 5 1 2 12


43

Table 8. AM, Mid-Day, and PM LOS.

AM PEAK


Franklin Avenue EB F E A A A A A A A

Franklin Avenue WB F F E E E A A A B

East River Parkway SB F F A A A A A A A

East River Parkway NB F F F F F A A A D

27th Avenue SB E E A A A A A A A

Overall F F D C C A A A B

10:00-11:00 AM


Franklin Avenue EB D D A A A A A A A

Franklin Avenue WB D E A A A A A A A

East River Parkway SB E E A A A A A A A

East River Parkway NB E E A A A A A A A

27th Avenue SB D D A A A A A A A

Overall D D A A A A A A A

PM PEAK


Franklin Avenue EB F E A A A A A A A

Franklin Avenue WB F F A A A A A A A

East River Parkway SB F F F F F A A A C

East River Parkway NB F F B B B A A A B

27th Avenue SB F F A A A A A A A

Overall F F F D C A A A B


44

Figure 31. Scenario 1 Approach Delay.



45

Figure 33. Scenario 3a Approach Delay.

Figure 34. Scenario 3b Approach Delay.


46


Figure 36. Scenario 5a Approach Delay.


47

Figure 37. Scenario 5b Approach Delay.



48


Scenarios 1 and 2 have very similar results, however Scenario 2 is clearly an

improvement. The allowance of additional movements in Scenario 2 drastically reduces

the mean delay for the Franklin Avenue EB approach by 26%, and the peak hour mean

delay by 25%. Overall, the intersection displays an 8% reduction in mean delay. The

gains are entirely felt only by the Franklin Avenue EB approach, however, and the delays

on the other four approaches remain virtually unchanged. While this is an

improvement, it does not help to reduce the longest delays felt in the system on the

East River Parkway SB approach.

The East River Parkway SB approach consistently displays more congestion during the

PM peak hours than the other approaches. Scenarios 3a and 3b, in fact, are likely to

make congestion worse on East River Parkway SB than it currently experiences in

Scenario 1. As the literature made clear, extremely long delays can be the result of

uneven flow through a roundabout. Scenarios 3a and 3b demonstrate this phenomenon

well. As previously mentioned, 452 of the 486 vehicles entering the roundabout from

the Franklin Avenue WB approach during the PM peak hour want to exit traveling west

on Franklin Avenue. Since the East River Parkway NB approach exhibits such low

demand, the Franklin Avenue WB approach is able to proceed nearly unchecked. The

combination of an entry with high flow proceeded by an entry with very low flow is

often the cause of uneven roundabout flow. A steady stream of vehicles proceeding


49

from the Franklin Avenue WB approach past the East River Parkway SB approach results

in long queuing on East River Parkway SB.

In addition, the large number of pedestrians crossing the western Franklin Avenue

approach often results in vehicles stopped in the exit lane traveling west on Franklin

Avenue. The queue often backs up into the roundabout, and the East River Parkway SB

approach is impacted more than other approaches. This is demonstrated by the

difference in East River Parkway SB delay between Scenarios 3a and 3b. In Scenario 3a,

all vehicles immediately yielded to pedestrians, resulting in a maximum average delay of

421 s/veh on the East River Parkway SB approach. This was by far the largest estimated

delay recorded in any of the scenarios, and a 114% increase over the East River Parkway

SB delay in Scenario 1. In Scenario 3b, all pedestrians yielded to passing vehicles,

resulting in a maximum average delay of 183 s/veh on the East River Parkway SB

approach, a 57% improvement over Scenario 3a, attributable only to the removal of

delay caused by pedestrians. Indeed, Scenario 3b exhibited a reduction in total mean

delay of 43 %.

Despite their flaws, Scenarios 3a and 3b are still somewhat attractive. Total mean delay

was reduced from 72 s/veh to between 9 and 16 s/veh. Scenario 3a exhibited dramatic

improvements on all approaches except East River Parkway SB during the PM peak hour.

Scenario 3 demonstrates the ability of a roundabout to nearly eliminate vehicle delay

during times of low traffic flow. During the AM peak hour, Scenario 3 also exhibits

uneven flows, but even the most heavily impacted entrance, East River Parkway NB,

displays an improvement over Scenario 1. And while the East River Parkway SB

approach is estimated to see a substantial increase in delay time with Scenario 3, the

total maximum 15 minute mean delay remains about the same as Scenario 1.

Scenario 4 marks significant improvements over Scenario 3. The added slip lane results

in a reduction of mean delay on East River Parkway SB to 110 s/veh. While this is still

LOS F, it is a dramatic improvement over Scenario 3. Individual approaches operate at

LOS F during peak hours, the roundabout as a whole is never estimated to operate at

less than LOS C. Scenarios 5 and 6 demonstrate that a two lane roundabout with two

lane entrance and exit roadways will eliminate nearly all delay at all times of the day.

Scenarios 5 and 6 are estimated to operate at LOS A at all times – even during peak

hours. Scenario 7 allows some approaches to operate at LOS D during peak hours but

still offers an overall LOS B during peak hours.

Figure 40 displays the system-wide average pedestrian delay for all seven scenarios.

The results of the seven scenarios on pedestrian delay are not surprising. Scenarios 1

and 2 are very similar. Although Scenario 2 provided additional opportunities for

pedestrians to cross than Scenario 1 offers, it does not appear to have a substantial

impact. Overall, Scenario 2 reduced overall pedestrian delay by only 1 second. It is

interesting to note that scenarios 4 and 6, which utilize pedestrian signals impose higher

levels of delay on pedestrians than scenarios 3b and 5b, which assumes that pedestrians

always yield to vehicles. The presence of pedestrian signals requires that all pedestrians


50

incur delay while waiting for the vehicles to pass through the yellow and all red phases.

Each pedestrian is guaranteed to incur at least 10 seconds of control delay while passing

a pair of entrance and exit lanes, unless they arrive just in time to become part of a

pedestrian platoon. It is also interesting to note that even in Scenario 3b, where

pedestrians always yield to vehicles, the maximum average delay is still only 20 seconds

per pedestrian. Of course, Scenarios 3a, 5a, and 6 assume that vehicles always yield to

pedestrians, so these scenarios are barely visible at the bottom of Figure 40.

Figure 40. Mean Pedestrian Delay.

Figure 41 displays the system-wide bicycle delay for all seven scenarios. It is important

to recall that in all seven scenarios, it is assumed that bicycles do not wait in vehicle

queues, but instead are able to bypass the queues by riding along the far right side of

the roadway, only incurring delay within the intersection and at decision points as

discussed earlier. Thus, it is clear that the delay incurred in Scenarios 1 and 2 is almost

entirely time stopped at a red light at the five-way intersection. Similar to the

pedestrian and vehicle estimates, Scenario 2 is only a slight improvement over scenario

1. Scenarios 3-7 assume that bicycles only join the vehicle queue about 50 feet before

the roundabout, so they do not incur delay waiting in queues, however they do incur

delay waiting to enter the roundabout and while within the roundabout. In this respect,

Scenarios 3-7 are all roughly similar. Bicyclists who do not bypass the queues by riding

along the right edge of the roadway would incur the same amount of delay as the cars.


51

Figure 41. Mean Bicycle Delay.

9.0 MEASURE OF EFFECTIVENESS – TRAFFIC DIVERSION

Tables 9-14 show the levels of observed traffic from each of the seven scenarios. Since

AIMSUN utilizes the a logit function to calculate the probability of choosing each route,

and the path costs are essentially the travel times on each route, we would expect that

the number of cars who choose to divert onto the local streets is directly related to the

delay time imposed on each vehicle. The speed limits on Franklin Avenue, East River

Parkway, and 27th Avenue range from 25-30 mph. To regulate the number of vehicles

choosing to divert and calibrate the model to divert approximately the right number of

vehicles in Scenario 1, the speed limits on the local streets were lowered enough to

discourage most drivers from using them. The speed limits used ranged between 5 and

10 mph on each of the local streets. While in reality, drivers can (and do) drive faster

than this on the local streets (probably as fast as 25 mph), if the speed limits were not

set unrealistically low, most drivers would choose to use these streets instead of the

five-way intersection.

Most drivers do not divert off the main streets, even if it would lower their travel time.

It is reasonable to assume, however, that the greater the delay time on the main

streets, the more likely drivers are to divert, often out of frustration. Tables 8

demonstrates the increased probability that drivers will choose to divert onto other

routes as the difference between the costs of each route decreases. Drivers traveling

south on East River Parkway SB are subjected to much larger delay times in Scenarios 3a


52

and 3b than in the other scenarios. Table 9 shows that many more drivers diverted in

Scenarios 3a and 3b than in the other scenarios.

Since alternative route choices are only shown here between 3:30 and 6:30 PM, when

the most significant delay occurs on the East River Parkway SB approach, it is not

surprising that many vehicles diverted onto Yale Eastbound and Thornton Southbound,

but traffic volumes on Yale Westbound and Thornton Northbound were relatively

unchanged. It is likely that during the AM peak period, the Northbound and

Westbound local streets saw increased traffic volumes. Scenarios 3a and 3b caused

significant diversion, while Scenarios 5a, 5b and 6 caused virtually no diversion.

Scenarios 4 and 7 caused intermediate levels of diversion.

Table 9. Traffic volumes on Yale Avenue EB West of 27th

Avenue.

SCENARIO Observed 1 2 3a 3b 4 5a 5b 6 7

15:30 8 9 8 5 2 4 1 0 0 2

15:45 4 8 8 4 1 5 1 1 0 3

16:00 5 4 4 6 3 3 1 2 0 4

16:15 7 6 4 8 2 2 2 3 1 3

16:30 4 8 6 10 15 4 0 2 0 4

16:45 10 12 12 32 20 6 1 0 2 5

17:00 11 10 12 46 28 10 0 1 3 5

17:15 8 10 11 69 26 19 2 0 0 6

17:30 9 7 9 68 35 17 3 2 0 7

17:45 7 6 7 65 26 17 0 2 1 3

18:00 7 4 10 51 10 9 1 3 0 0

18:15 4 2 9 31 4 2 0 0 2 0

Table 10. Traffic Volumes on Yale Avenue WB West of 27th

Avenue.


15:30 3 5 8 2 3 2 0 0 0 5

15:45 1 4 2 5 3 3 1 1 0 3

16:00 3 2 7 4 3 2 2 2 1 4

16:15 7 7 8 3 3 6 0 2 0 3

16:30 4 6 10 3 3 2 1 1 2 2

16:45 12 12 10 2 2 1 4 0 2 5

17:00 4 16 14 4 5 4 0 1 0 4

17:15 6 10 16 9 6 5 3 4 1 3

17:30 6 9 12 3 6 3 2 1 0 4

17:45 7 10 14 0 5 2 0 0 3 4

18:00 6 8 13 4 4 1 5 2 3 4

18:15 7 7 9 4 2 6 0 0 0 3


53

Table 11. Traffic Volumes on Yale Avenue EB East of 27th

Avenue.


15:30 11 7 9 2 0 7 1 1 4 2

15:45 9 9 8 1 1 2 0 0 0 4

16:00 11 10 5 1 3 3 2 2 2 4

16:15 9 11 11 8 2 7 2 2 2 3

16:30 21 28 13 12 12 5 0 0 0 2

16:45 34 32 10 17 17 8 3 2 1 5

17:00 30 27 23 16 26 12 0 0 0 6

17:15 24 22 30 78 23 16 1 1 3 7

17:30 20 24 24 71 33 14 1 0 0 6

17:45 18 20 21 61 30 12 0 0 5 3

18:00 12 12 13 44 8 12 2 2 0 6

18:15 9 7 8 27 2 5 0 3 2 6

Table 12. Traffic Volumes on Yale Avenue WB East of 27th

Avenue.


15:30 5 8 5 2 3 2 2 0 0 0

15:45 3 7 5 2 4 3 0 0 1 2

16:00 7 9 9 2 2 1 1 0 2 4

16:15 7 8 8 2 5 2 2 2 0 1

16:30 6 9 9 2 4 2 0 0 2 2

16:45 20 16 9 3 2 0 2 3 2 3

17:00 17 15 10 4 3 4 2 3 0 2

17:15 18 17 15 5 1 5 0 0 2 3

17:30 20 15 14 1 4 5 3 1 0 2

17:45 15 14 17 2 4 4 0 0 1 2

18:00 12 10 15 4 2 4 4 2 0 0

18:15 10 10 8 5 3 5 0 0 0 1


54

Table 13. Traffic Volumes on Thornton Street NB South of Franklin Avenue.


15:30 7 7 6 0 2 2 0 0 2 3

15:45 6 8 6 2 3 3 1 0 1 5

16:00 5 6 3 1 1 2 1 0 2 6

16:15 3 7 3 0 3 5 0 1 2 3

16:30 7 8 11 3 3 6 2 1 1 3

16:45 9 12 12 1 2 6 2 0 3 6

17:00 6 8 8 0 2 3 0 2 1 3

17:15 8 9 12 3 1 2 1 2 1 5

17:30 9 11 14 1 2 3 2 2 4 4

17:45 6 8 10 2 3 5 3 0 2 3

18:00 3 4 9 4 1 5 2 2 1 2

18:15 5 3 7 5 2 5 0 0 2 2

Table 14. Traffic Volumes on Thornton Street SB South of Franklin Avenue.


15:30 3 4 2 1 3 4 0 2 0 2

15:45 5 4 7 2 1 2 2 2 2 2

16:00 9 6 4 2 2 5 2 1 5 5

16:15 7 9 3 8 3 2 1 2 3 2

16:30 16 12 8 15 9 1 2 1 1 1

16:45 19 17 10 17 14 2 3 1 3 3

17:00 15 17 12 26 19 3 1 4 0 4

17:15 10 15 11 58 20 10 4 1 0 4

17:30 14 16 10 41 25 17 3 0 0 3

17:45 12 15 12 39 14 13 1 3 0 5

18:00 8 12 7 34 7 12 2 1 1 3

18:15 7 8 6 21 2 6 2 0 0 0

10.0 DISCUSSION

To determine which of the alternatives is optimal, the objective must be clearly

stated. This is not as easy as it might seem. There are several competing objectives that

must be balanced. Possibilities include but are not limited to the following:

• minimize total vehicle delay time

• minimize pedestrian delay time


55

• maximize pedestrian safety

• minimize paved surface area

• maximize vehicle safety

• minimize vehicle conflict points

• minimize vehicle-pedestrian conflict points

• minimize bicycle delay

• minimize traffic diversion onto local streets

• minimize construction and maintenance costs

While it is not within the scope of this study to consider each of these objectives in

detail, several of them can be considered. Those wishing to minimize total vehicle delay

will likely prefer Scenario 5, the two lane, unsignalized roundabout with two entrance

and two exit lanes at each approach. This scenario nearly eliminated all delay and

operates at LOS A at all times. From this standpoint, Scenario 5 is an attractive

alternative. However, this option is also likely the least safe option for pedestrians and

vehicles, and local residents might find that it moves traffic too quickly, encouraging

some to call for increased traffic calming. Indeed, it is rare to locate intersections of this

size in urban areas that operate at LOS A at all times. In addition, drivers in the U.S. are

largely unfamiliar with two-lane roundabouts and may not be comfortable driving in the

intersection, which might lower the expected capacity and cause unanticipated delay.

Those wishing to minimize total pedestrian delay will also prefer either Scenario 3 or

Scenario 5, but this analysis assumes that all pedestrians are able and comfortable

crossing unsignalized roadways. An unsignalized option could prove daunting for the

vision impaired, wheelchairs, children, or any other pedestrians unable to move as

quickly as those in this model. Pedestrian-vehicle conflict points are minimized in any of

the alternatives where the entry and exit lanes are only one lane where pedestrians

cross (Scenarios 3, 4, and 7).

Scenario 3 is likely to minimize the total pavement surface area, an attractive option for

those wishing to encourage greater stormwater infiltration, and while, Scenario 3 is

probably the best option for 22 hours of each day its limitations during the PM peak

hour are significant and would likely lead to increased levels of delay on only the East

River Parkway SB approach. To be certain, Scenario 3 likely satisfies most of these

potential objectives, other than minimizing vehicle delay, and even that objective is

satisfied for all but 2 hours each weekday.

To choose between the options, it is important to understand the basic assumptions of

this study – namely, that regardless of the alternative chosen, traffic demand will

remain constant. This is almost assuredly not the case, as many drivers seeking to

minimize travel times will modify their usual routes in response to the reconstruction of

this intersection. It is possible, for example, that if Scenario 5 is constructed, drivers

currently using other routes would begin traveling through this intersection because it

now offers a decreased travel time when compared to their current route. It is also

possible, that if Scenario 3 is constructed, the predicted delay times will not materialize


56

because drivers leaving the University of Minnesota will choose not to travel through

this intersection and use a different route instead. Alternatively, drivers leaving the

University of Minnesota may continue to travel through this intersection, but will divert

on local streets outside of the area modeled in this study to approach the roundabout

from 27th Avenue where delay times are expected to be significantly shorter.

Given the high levels of pedestrians and bicyclists in the area, it seems like a good idea

to implement pedestrian signals across the western Franklin Avenue approach. While

Scenarios 4 and 6 included pedestrian signals across all approaches (except the

Northbound East River Parkway approach), the others may not be required. It is true

that many pedestrians will choose not to use the pedestrian signal. If a pedestrian

arrives at the intersection at an uncongested time, many will choose to cross without

pressing the button, and essentially, the approach becomes uncontrolled. Pedestrian

compliance at this intersection is already relatively low. However, many pedestrians will

utilize the signals.

Scenario 7 appears to satisfy several of the objectives. Pedestrians are only asked to

cross single-lane entrances and exits, vehicle and pedestrian delays are reasonably low,

and vehicle safety is enhanced by using only single lane exits. However it is more

complicated than the other intersections and those seeking pedestrian friendly urban

design aspects may find it unattractive.

It is clear, however, that any of the proposed scenarios are better than the current

intersection design if the objective is to minimize mean vehicle or pedestrian delay.

Decision-makers can be confident, based on Figure 30 alone, that total vehicle delay will

be significantly reduced through implementation of a roundabout at this complex

intersection. Table 15 displays a summary of findings.


57

Table 15. Summary of Findings.


Number of Circulating Lanes - - 1 1 1 2 2 2 2

Number of Lanes per Entry - - 1 1 1 2 2 2 2

Number of Lanes per Exit - - 1 1 1 2 2 2 1

Right Turn Slip Lane - - - - Yes - - - Yes

Flared Entry Way - - - - - - - - Yes

Pedestrian Signals - - - - Yes - - Yes -

Number of Lanes at Crosswalks - - 1-2 1-2 1-2 2-4 2-4 2-4 1-2

Average Vehicle Delay 72 66 16 9 9 3 2 4 5

Maximum Average Vehicle Delay 122 108 116 48 34 5 4 7 13

Max Average Delay on Any Approach 197 195 421 183 130 10 9 12 45

Average Pedestrian Delay 64 63 1 7 16 1 3 14 1

Maximum Average Pedestrian Delay 99 97 5 19 26 1 7 23 1

Average Bicycle Delay 52 50 3 1 1 1 1 1 4

Maximum Average Bicycle Delay 92 83 12 12 14 5 1 2 12

Minimizes Vehicle Conflict Points - - Yes Yes - - - - -

Minimizes Ped/Vehicle Conflict Points - - Yes Yes - - - - Yes

Minimizes Average Vehicle Delay - - - - - Yes Yes - -

Minimizes Average Pedestrian Delay - - Yes - - Yes - - Yes

Minimize Diversion onto Local Streets - - - - - Yes Yes Yes Yes


58

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Al-Masaeid, H.R., and M.Z. Faddah. "Capacity of Roundabouts in Jordan." Transportation

Research Record 1572, 1997: 76-85.

Al-Omari, H., H.R. Al-Masaeid, and Y.S. Al-Shawabkah. "Development of a Delay Model

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60

APPENDIX


61

Turning Movements Collected by Author. Shaded cells indicate values estimated from surrounding cells.

From 27th Ave

From South East River

Road From West Franklin Ave From North East River Road From East Franklin Ave

Total

Start Time

W

Franklin

S

ERR

E

Franklin

N

ERR 27th

N

ERR

W

Franklin

E

Franklin 27th

N

ERR

S

ERR

S

ERR

E

Franklin 27th

W

Franklin 27th

N

ERR

W

Franklin

9/25/2007 6:00 AM 8 0 0 0 0 5 5 17 8 4 0 2 0 0 0 0 2 15 66

9/25/2007 6:15 AM 7 1 1 0 0 16 3 12 11 8 3 3 0 0 2 0 3 22 92

9/25/2007 6:30 AM 16 0 0 1 0 21 11 16 20 13 5 3 0 0 7 1 11 35 160

9/25/2007 6:45 AM 16 0 2 1 4 28 10 19 10 16 4 10 1 1 10 0 5 53 190

9/25/2007 7:00 AM 16 0 1 0 1 27 19 16 18 19 5 0 1 1 9 0 7 52 192

9/25/2007 7:15 AM 30 1 0 0 4 53 45 24 12 30 6 11 1 0 7 0 14 50 288

9/25/2007 7:30 AM 33 2 1 0 3 67 45 39 33 33 9 9 4 0 15 0 29 75 396

9/25/2007 7:45 AM 35 3 1 0 5 83 48 42 35 35 8 10 5 0 17 0 16 81 423

9/25/2007 8:00 AM 29 4 1 1 7 83 36 45 36 36 7 12 6 1 17 3 17 67 407

9/25/2007 8:15 AM 23 4 0 1 1 62 42 48 38 42 9 9 2 0 19 0 16 78 392

9/25/2007 8:30 AM 27 7 0 2 6 90 37 50 39 47 10 10 4 0 15 0 14 60 417

9/25/2007 8:45 AM 31 9 0 2 5 41 28 10 4 2 13 0 21 66 232

9:00 AM

9:15 AM

9:30 AM

9:45 AM

10:00 AM

10:15 AM

10:30 AM

10:45 AM

11:00 AM

11:15 AM

11:30 AM

11:45 AM

12:00 PM

12:15 PM

12:30 PM

9/13/2007 12:45 PM 3 12 29 39 27 16 10 8 6 2 22 1 6 33 214

9/13/2007 1:00 PM 33 2 1 2 0 7 10 36 28 16 11 10 3 1 27 3 9 48 247

9/13/2007 1:15 PM 30 2 1 1 1 8 11 32 29 16 12 16 9 0 22 1 6 33 231

9/13/2007 1:30 PM 28 3 0 1 3 14 19 34 32 10 18 14 6 3 27 0 5 45 261

9/13/2007 1:45 PM 25 3 0 0 0 10 8 41 36 13 14 24 9 2 31 0 4 47 266


62

9/13/2007 2:00 PM 31 3 0 2 3 12 7 48 39 15 9 24 4 1 20 7 8 37 270

9/13/2007 2:15 PM 37 3 0 3 1 15 15 54 51 21 15 26 3 1 19 3 5 54 325

9/13/2007 2:30 PM 39 3 1 2 2 18 12 60 62 26 21 22 9 3 35 6 7 50 377

9/13/2007 2:45 PM 40 2 1 1 5 24 16 62 50 26 24 18 9 2 17 3 6 91 397

9/13/2007 3:00 PM 43 3 1 2 3 13 13 64 38 26 26 25 4 0 37 3 10 88 398

9/13/2007 3:15 PM 46 3 1 2 4 19 18 62 37 26 28 42 6 1 29 1 8 76 408

9/6/2007 3:30 PM 53 3 1 2 3 13 19 59 36 26 29 40 10 1 52 1 8 65 421

9/6/2007 3:45 PM 60 3 2 2 2 20 15 86 58 18 27 43 7 3 35 3 4 80 467

9/6/2007 4:00 PM 66 3 2 1 4 15 19 87 68 16 33 48 13 1 24 1 7 65 473

9/6/2007 4:15 PM 73 3 2 1 2 12 22 78 60 15 29 63 11 1 49 5 8 79 513

9/6/2007 4:30 PM 80 2 1 2 4 18 14 69 52 13 25 78 16 0 48 0 9 87 517

9/6/2007 4:45 PM 86 1 0 2 2 19 16 63 54 15 26 54 15 2 32 2 8 105 502

9/6/2007 5:00 PM 77 2 1 1 4 18 36 57 56 17 26 71 16 1 48 1 5 120 556

9/6/2007 5:15 PM 67 2 1 0 5 19 24 64 53 20 34 63 13 0 37 3 3 83 490

9/6/2007 5:30 PM 59 2 1 1 3 13 23 70 50 23 41 58 13 1 31 1 3 92 485

9/6/2007 5:45 PM 50 3 1 2 3 24 20 70 37 27 25 43 9 1 22 0 12 63 411

9/6/2007 6:00 PM 42 3 1 2 2 17 19 65 36 15 20 45 10 0 23 2 2 43 347

9/6/2007 6:15 PM 33 3 1 3 2 15 13 29 8 2 24 1 3 39 176

6:30 PM

6:45 PM

7:00 PM

9/25/2007 7:15 PM 18 1 1 1 2 7 8 24 21 7 7 16 4 1 14 0 2 24 158

9/25/2007 7:30 PM 20 4 1 0 1 5 3 32 13 7 10 10 4 1 15 0 5 18 149

9/25/2007 7:45 PM 23 2 0 0 1 5 5 19 13 9 5 15 3 0 12 1 5 22 140

9/25/2007 8:00 PM 19 4 0 1 1 4 5 17 21 12 7 10 1 1 10 2 0 23 138

9/25/2007 8:15 PM 30 1 0 1 1 11 9 25 15 12 10 15 4 0 12 0 2 14 162

9/25/2007 8:30 PM 16 0 2 1 1 6 2 22 13 12 7 10 3 0 12 2 1 17 127

9/25/2007 8:45 PM 12 4 3 0 0 11 2 18 12 5 14 15 3 0 13 3 3 13 131

9/25/2007 9:00 PM 19 2 0 0 1 5 3 27 16 4 6 8 3 1 10 1 8 25 139

9/25/2007 9:15 PM 12 1 0 0 2 5 7 27 12 10 10 17 4 0 13 2 0 19 141

9/25/2007 9:30 PM 9 3 0 1 1 3 10 24 10 6 7 5 0 0 11 2 2 19 113

9/25/2007 9:45 PM 4 0 0 0 1 2 2 18 10 5 7 3 3 0 9 1 2 15 82

Total:

18931


63

Turning Movements Collected by the City of Minneapolis Public Works.

27th Av SE

Southwestbound


Road From W Franklin From N ERR From E Franklin Total

Date Time

W

Franklin

S

ERR

E

Franklin

N

ERR 27th

N

ERR

W

Franklin

E

Franklin 27th

N

ERR

S

ERR

S

ERR

E

Franklin 27th

W

Franklin 27th

N

ERR

W

Franklin

6:00

6:15

9/27/2007 6:30 4 0 0 0 5 6 1 47 38 6 4 10 2 3 7 1 11 59 204

9/27/2007 6:45 12 0 0 0 1 56 15 35 26 23 3 13 6 0 3 2 15 75 285

9/27/2007 7:00 32 1 0 2 0 76 40 27 21 32 0 11 1 0 8 2 25 53 331

9/27/2007 7:15 27 0 0 0 4 81 46 24 40 36 3 19 6 5 19 3 30 90 433

9/27/2007 7:30 37 0 1 1 16 141 71 74 73 49 1 15 3 0 14 0 33 58 587

9/27/2007 7:45 33 0 2 0 7 124 59 60 47 40 5 12 2 0 21 2 17 122 553

9/27/2007 8:00 29 0 0 0 9 129 58 55 55 45 0 13 10 0 14 3 16 92 528

9/27/2007 8:15 18 0 2 0 1 137 62 55 45 31 3 6 2 2 19 4 17 101 505

9/27/2007 8:30 26 1 0 1 2 93 55 77 44 48 0 18 3 1 14 4 15 75 477

9/27/2007 8:45 19 0 1 1 9 90 17 46 60 28 0 9 10 1 4 2 23 121 441

9/27/2007 9:00 13 0 3 0 9 55 23 36 39 10 2 12 6 1 15 2 45 57 328

9:15

9/27/2007 9:30 19 1 4 1 0 62 26 33 35 26 0 9 2 3 3 4 16 39 283

9/27/2007 9:45 22 1 0 0 5 27 32 45 23 17 2 21 5 0 9 5 22 37 273

9/27/2007 10:00 19 0 2 2 1 19 11 29 33 8 3 16 4 2 7 2 16 24 198

9/27/2007 10:15 13 2 4 1 0 13 8 38 31 26 6 7 1 1 7 1 10 23 192

9/27/2007 10:30 13 1 2 1 2 17 15 18 17 18 4 14 9 1 17 5 17 47 218

9/27/2007 10:45 24 0 0 0 5 22 20 44 25 18 2 16 6 0 10 2 9 25 228

9/27/2007 11:00 17 2 3 2 5 22 19 35 26 12 3 10 4 3 15 5 10 20 213

9/27/2007 11:15 21 2 5 1 4 13 6 27 41 15 5 17 7 1 13 5 17 35 235

9/27/2007 11:30 27 0 2 2 6 21 8 52 35 11 6 23 10 1 28 5 0 34 271

9/27/2007 11:45 23 0 1 1 1 23 9 28 33 21 5 13 5 1 20 7 7 47 245

9/27/2007 12:00 35 5 2 0 1 24 8 35 52 13 10 28 3 0 29 3 13 48 309

9/27/2007 12:15 13 0 0 1 3 22 5 61 49 25 7 18 14 5 12 1 4 44 284

12:30

9/21/2007 12:45 14 6 2 0 4 35 9 23 22 11 7 23 13 3 15 2 39 65 293

9/21/2007 13:00 26 1 2 0 1 17 13 26 26 14 4 42 8 3 26 0 8 69 286

9/21/2007 13:15 36 2 2 0 1 32 10 87 51 13 12 24 6 2 17 3 2 91 391

9/21/2007 13:30 30 7 2 3 0 13 8 61 73 19 12 18 19 0 16 3 3 58 345

9/21/2007 13:45 26 2 8 2 0 20 20 65 74 20 13 44 8 1 26 2 8 41 380

9/21/2007 14:00 23 3 4 1 2 15 17 107 61 24 12 56 2 0 26 0 5 59 417


64

9/21/2007 14:15 32 1 4 1 1 17 16 101 81 29 15 52 9 0 44 4 6 49 462

9/21/2007 14:30 38 5 3 3 4 24 14 95 69 27 20 58 6 0 43 1 3 65 478

9/21/2007 14:45 40 2 3 0 2 30 18 89 58 20 11 49 4 4 23 5 6 81 445

9/21/2007 15:00 26 0 1 2 4 16 15 121 67 28 14 55 7 1 50 0 10 122 539

9/21/2007 15:15 57 3 6 2 6 34 11 111 86 16 21 85 17 2 71 1 4 86 619

9/21/2007 15:30 40 2 2 16 5 12 10 121 80 27 38 98 18 10 61 3 8 139 690

9/21/2007 15:45 63 0 7 2 1 35 14 150 94 26 21 62 19 2 34 1 4 114 649

9/21/2007 16:00 50 2 1 3 2 25 29 148 78 23 15 111 13 0 59 1 6 153 719

9/21/2007 16:15 40 0 0 0 5 28 34 138 77 25 10 122 11 2 72 4 7 112 687

9/21/2007 16:30 103 8 4 1 4 60 24 142 97 24 22 119 9 0 65 1 2 149 834

9/21/2007 16:45 79 4 0 1 5 31 35 138 87 17 17 127 12 0 68 0 3 154 778

9/21/2007 17:00 31 0 0 0 3 31 6 79 39 10 6 57 10 0 17 2 0 74 365

9/21/2007 17:15 35 2 3 6 0 14 3 51 51 27 7 97 17 0 40 0 6 148 507

9/21/2007 17:30 51 0 2 1 6 52 21 99 55 23 11 106 16 0 43 4 6 113 609

9/21/2007 17:45 35 2 0 1 4 25 22 79 40 23 15 101 16 0 46 2 9 76 496

9/21/2007 18:00 27 2 2 0 4 14 24 46 30 22 4 51 7 1 24 1 6 82 347

9/21/2007 18:15 40 1 4 1 4 27 14 67 54 20 9 47 25 5 14 1 2 90 425

9/21/2007 18:30 38 1 1 1 4 19 14 35 40 16 12 43 13 2 11 3 4 77 334

9/21/2007 18:45 23 1 6 3 0 17 7 35 38 11 9 28 13 1 17 6 3 52 270

19:00

19:15

19:30

19:45

20:00

20:15

20:30

20:45

21:00

21:15

21:30

21:45

Total: 19986


65

Combined Dataset Used in Microsimulation.

27th Av SE

Southwestbound


Road From W Franklin From N ERR From E Franklin Total

Start

Time

W

Franklin

S

ERR

E

Franklin

N

ERR 27th

N

ERR

W

Franklin

E

Franklin 27th

N

ERR

S

ERR

S

ERR

E

Franklin 27th

W

Franklin 27th

N

ERR

W

Franklin

6:00 8 0 0 0 0 5 5 17 8 4 0 2 0 0 0 0 2 15 66

6:15 7 1 1 0 0 16 3 12 11 8 3 3 0 0 2 0 3 22 92

6:30 10 0 0 1 5 14 6 32 29 10 5 7 2 3 7 1 11 47 187.5

6:45 14 0 2 1 3 42 13 27 18 20 4 12 4 1 7 2 10 64 240.5

7:00 24 1 1 2 1 52 30 22 20 26 5 11 1 1 9 2 16 53 273.5

7:15 29 1 0 0 4 67 46 24 26 33 5 15 4 5 13 3 22 70 365

7:30 35 2 1 1 10 104 58 57 53 41 5 12 4 0 15 0 31 67 493

7:45 34 3 2 0 6 104 54 51 41 37 7 11 4 0 19 2 17 102 490.5

8:00 29 4 1 1 8 106 47 50 46 41 7 13 8 1 16 3 17 80 473.5

8:15 21 4 2 1 1 100 52 51 41 36 6 8 2 2 19 4 17 90 455

8:30 27 4 0 1 4 92 46 64 42 48 10 14 4 1 15 4 15 68 454.5

8:45 25 9 1 2 7 66 23 46 60 28 0 10 7 2 9 2 22 94 409.5

9:00 13 0 3 0 9 55 23 36 39 10 2 12 6 1 15 2 45 57 328

9:15 16 1 4 1 5 59 25 35 37 18 1 11 4 2 9 3 31 48 305.5

9:30 19 1 4 1 0 62 26 33 35 26 0 9 2 3 3 4 16 39 283

9:45 22 1 0 0 5 27 32 45 23 17 2 21 5 0 9 5 22 37 273

10:00 19 0 2 2 1 19 11 29 33 8 3 16 4 2 7 2 16 24 198

10:15 13 2 4 1 0 13 8 38 31 26 6 7 1 1 7 1 10 23 192

10:30 13 1 2 1 2 17 15 18 17 18 4 14 9 1 17 5 17 47 218

10:45 24 0 0 0 5 22 20 44 25 18 2 16 6 0 10 2 9 25 228

11:00 17 2 3 2 5 22 19 35 26 12 3 10 4 3 15 5 10 20 213

11:15 21 2 5 1 4 13 6 27 41 15 5 17 7 1 13 5 17 35 235

11:30 27 0 2 2 6 21 8 52 35 11 6 23 10 1 28 5 0 34 271

11:45 23 0 1 1 1 23 9 28 33 21 5 13 5 1 20 7 7 47 245

12:00 35 5 2 0 1 24 8 35 52 13 10 28 3 0 29 3 13 48 309

12:15 13 0 0 1 3 22 5 61 49 25 7 18 14 5 12 1 4 44 284

12:30 14 3 1 1 3 23 12 46 37 19 8 17 12 4 15 1 13 47 274.25

12:45 14 6 2 0 4 24 19 31 25 14 9 16 10 3 19 2 23 49 264.5

13:00 30 2 2 2 1 12 12 31 27 15 8 26 6 2 27 3 9 59 269.25

13:15 33 2 1 1 1 20 11 60 40 15 12 20 8 2 20 2 4 62 312.52

13:30 29 5 1 2 3 14 14 48 53 15 15 16 13 3 22 3 4 52 307.7

13:45 26 3 8 2 0 15 14 53 55 16 13 34 9 2 29 2 6 44 328.75

14:00 27 3 4 1 3 14 12 78 50 20 11 40 3 1 23 7 7 48 349.25


66

14:15 35 2 4 2 1 16 16 78 66 25 15 39 6 1 32 4 6 52 396

14:30 38 4 2 3 3 21 13 78 66 27 21 40 8 3 39 4 5 58 428.75

14:45 40 2 2 1 4 27 17 76 54 23 17 34 7 3 20 4 6 86 421.25

15:00 35 3 1 2 4 15 14 93 53 27 20 40 6 1 44 3 10 105 471.75

15:15 52 3 4 2 5 27 15 86 62 21 24 64 12 2 50 1 6 81 513.5

15:30 46 3 2 9 4 13 15 90 58 27 34 69 14 6 57 2 8 102 555.375

15:45 61 3 4 2 2 28 15 118 76 22 24 53 13 3 35 2 4 97 559.25

16:00 58 3 1 2 3 20 24 118 73 20 24 80 13 1 42 1 7 109 596.625

16:15 57 3 2 1 4 20 28 108 69 20 20 93 11 2 61 5 8 96 602.75

16:30 91 5 3 1 4 39 19 106 75 19 24 99 13 0 57 1 6 118 676

16:45 83 3 0 2 4 25 26 101 71 16 21 91 14 2 50 2 6 130 641.75

17:00 54 2 1 1 4 25 21 68 48 14 16 64 13 1 33 2 5 97 464.75

17:15 51 2 2 6 5 17 14 57 52 24 20 80 15 0 39 3 5 116 505.5

17:30 55 2 2 1 5 33 22 85 53 23 26 82 15 1 37 3 5 103 548.375

17:45 43 2 1 1 4 25 21 75 39 25 20 72 13 1 34 2 11 70 455.5

18:00 34 2 2 2 3 16 22 56 33 19 12 48 9 1 24 2 4 63 348.375

18:15 37 2 3 2 3 21 14 67 54 20 9 38 17 4 19 1 3 65 375.5

18:30 38 1 1 1 4 19 14 35 40 16 12 43 13 2 11 3 4 77 334

18:45 23 1 6 3 0 17 7 35 38 11 9 28 13 1 17 6 3 52 270

19:00 21 1 4 2 1 12 8 30 30 9 8 22 9 1 16 3 3 38 214

19:15 18 1 1 1 2 7 8 24 21 7 7 16 4 1 14 0 2 24 158

19:30 20 4 1 0 1 5 3 32 13 7 10 10 4 1 15 0 5 18 149

19:45 23 2 0 0 1 5 5 19 13 9 5 15 3 0 12 1 5 22 140

20:00 19 4 0 1 1 4 5 17 21 12 7 10 1 1 10 2 0 23 138

20:15 30 1 0 1 1 11 9 25 15 12 10 15 4 0 12 0 2 14 162

20:30 16 0 2 1 1 6 2 22 13 12 7 10 3 0 12 2 1 17 127

20:45 12 4 3 0 0 11 2 18 12 5 14 15 3 0 13 3 3 13 131

21:00 19 2 0 0 1 5 3 27 16 4 6 8 3 1 10 1 8 25 139

21:15 12 1 0 0 2 5 7 27 12 10 10 17 4 0 13 2 0 19 141

21:30 9 3 0 1 1 3 10 24 10 6 7 5 0 0 11 2 2 19 113

21:45 4 0 0 0 1 2 2 18 10 5 7 3 3 0 9 1 2 15 82

Total:

20548.22

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