operational and safety impacts of closing the ......2020/05/26 · traffic operations were...

OPERATIONAL AND SAFETY IMPACTS OFCLOSING THE VIENTO DRIVE ACCESS TOUS 285SANTA FE, NEW MEXICO

Prepared By:

6100 Uptown Blvd NE, Suite 700Albuquerque, NM 87110

May 26, 2020

NMDOT

Operational and Safety Impacts of Closing Viento Drive/US 285 Access Santa Fe, New Mexico

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TABLE OFCONTENTS

1 INTRODUCTION ........................................................ 1

1.1 Study Purpose ........................................................................ 1

1.2 Study Procedure ..................................................................... 1

2 EXISTING AREA CHARACTERISTICS ..................... 3

2.1 General Area Characteristics ................................................. 3

2.2 Existing Traffic Volumes ........................................................ 3

2.3 Field Observations.................................................................. 4

2.4 Collision Analysis ................................................................... 62.4.1 Intersection Crashes ................................................................................................ 62.4.2 Corridor Crashes ...................................................................................................... 7

3 FUTURE VOLUMES .................................................. 9

3.1 2040 Forecasts ........................................................................ 9

4 PROPOSED CONDITIONS...................................... 10

4.1 Re-Distribution of Traffic with Proposed Closure of VientoDrive ...................................................................................... 10

4.2 Proposed Conditions Volumes ............................................ 11

5 OPERATIONS ANALYSIS ....................................... 14

5.1 AM Peak Hour Operational Analysis .................................... 15

5.2 PM Peak Hour Operational Analysis .................................... 16

5.3 US 285/Alamo Drive Eastbound Queue Impacts ................. 18

6 CONCLUSION ......................................................... 22

6.1 Conclusions .......................................................................... 22

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TABLESTABLE 1 - DISTRIBUTION OF VEHICLES THAT TURNED

RIGHT FROM EASTBOUND VIENTO DRIVEONTO SOUTHBOUND US 285 .................................. 4

TABLE 2 - STUDY INTERSECTION TOP CONTRIBUTINGFACTORS .................................................................. 6

TABLE 3 - LEVEL OF SERVICE DEFINITIONS FORUNSIGNALIZED INTERSECTIONS (HCM 6THEDITION) ................................................................. 14

TABLE 4 - LEVEL OF SERVICE DEFINITIONS FORSIGNALIZED INTERSECTIONS (HCM 6THEDITION) ................................................................. 14

TABLE 5 - AM PEAK HOUR OPERATIONAL ANALYSIS OF US285 AT ALAMO DRIVE ............................................. 15

TABLE 6 - AM PEAK HOUR OPERATIONAL ANALYSIS OFALAMO DRIVE AT CALLE MEJIA ............................ 15

TABLE 7 - AM PEAK HOUR OPERATIONAL ANALYSIS OFALAMO DRIVE AT GUADALUPE STREET............... 15

TABLE 8 – CHANGE IN DELAY (SECONDS) WITH THECLOSURE OF VIENTO DRIVE (US 285 ATALAMO DRIVE) ........................................................ 16

TABLE 9 - CHANGE IN DELAY (SECONDS) WITH THECLOSURE OF VIENTO DRIVE (ALAMODRIVE AT CALLE MEJIA) ........................................ 16

TABLE 10 - CHANGE IN DELAY (SECONDS) WITH THECLOSURE OF VIENTO DRIVE (GUADALUPESTREET AT ALAMO DRIVE) .................................... 16

TABLE 11 - PM PEAK HOUR OPERATIONAL ANALYSIS OFUS 285 AT ALAMO DRIVE ....................................... 17

TABLE 12 - PM PEAK HOUR OPERATIONAL ANALYSIS OFALAMO DRIVE AT CALLE MEJIA ............................ 17

TABLE 13 - PM PEAK HOUR OPERATIONAL ANALYSIS OFGUADALUPE STREET AT ALAMO DRIVE............... 17

TABLE 14 – PM PEAK: CHANGE IN DELAY (SECONDS) WITHTHE CLOSURE OF VIENTO DRIVE (US 285AT ALAMO DRIVE) .................................................. 18

TABLE 15 - PM PEAK: CHANGE IN DELAY (SECONDS) WITHCLOSURE OF VIENTO DRIVE (ALAMODRIVE AT CALLE MEJIA) ........................................ 18

TABLE 16 - PM PEAK: CHANGE IN DELAY (SECONDS) WITHCLOSURE OF VIENTO DRIVE (GUADALUPESTREET AT ALAMO DRIVE) .................................... 18

TABLE 17 - 90TH PERCENTILE EASTBOUND QUEUELENGTHS (FEET) AT US 285/ALAMO DRIVE.......... 19

TABLE 18 - 2014 TO 2018 TOTAL CRASHES (ACTUAL &PREDICTED) ........................................................... 20

TABLE 19 - 2014 TO 2018 CRASH FREQUENCY (ACTUAL &PREDICTED) ........................................................... 21

TABLE 20 - 2014 TO 2018 FATAL/INJURY CRASHFREQUENCY (ACTUAL & PREDICTED) .................. 21

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TABLE 21 - 2014 TO 2018 PROPERTY DAMAGE ONLY (PDO)CRASH FREQUENCY (ACTUAL &PREDICTED) ........................................................... 21

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FIGURESFIGURE 1 - STUDY AREA .................................................................... 2FIGURE 2 - EXISTING CONDITIONS (2020) PEAK HOUR AM

(PM) VOLUMES ......................................................... 4FIGURE 3 - FUTURE CONDITIONS WITH VIENTO DRIVE

OPEN (2040) PEAK HOUR AM (PM)VOLUMES .................................................................. 9

FIGURE 4 - RE-DISTRIBUTION OF 2020 VOLUMESTHROUGH THE NETWORK DUE TO THEVIENTO DRIVE CLOSURE IN THE AM (PM)PEAK HOURS .......................................................... 10

FIGURE 5 - RE-DISTRIBUTION OF 2040 VOLUMESTHROUGH THE NETWORK DUE TO THEVIENTO DRIVE CLOSURE IN THE AM (PM)PEAK HOURS .......................................................... 11

FIGURE 6 - 2020 CONDITIONS WITH VIENTO DRIVECLOSED PEAK HOUR AM (PM) VOLUMES ............ 12

FIGURE 7 - 2040 CONDITIONS WITH VIENTO DRIVECLOSED PEAK HOUR AM (PM) VOLUMES ............ 13

APPENDICESA TRAFFIC COUNTS

B CRASH DATA

C 2040 FORECASTS

D HCS7 OPERATIONAL OUTPUTS

E IHSDM ANALYSIS RESULTS

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1 INTRODUCTIONThe New Mexico Department of Transportation (NMDOT) is proposing the closure of the Viento Driveaccess point to US 285 in Santa Fe, New Mexico. The existing roadway provides access from Calle Mejiato southbound US 285 just north of the US 285/Alamo Drive signalized intersection. Calle Mejia is a localroad with both residential and commercial land uses.

1.1 STUDY PURPOSEThe purpose of this study was to analyze the traffic impacts of closing the Viento Drive access to US 285.The closure will result in the traffic to/from Viento Drive being re-distributed through the network andaccessing US 285 at either Alamo Drive or North Guadalupe Street. An operational assessment ofchange condition will be completed to determine the impact of the proposed change. A crash historyevaluation of the impacted intersections was also included in the analysis along with the intersectingcorridors.

1.2 STUDY PROCEDUREThe study was conducted using established traffic engineering procedures. The potential traffic impacts ofthe re-routed traffic were evaluated at the following intersections:

· Viento Drive/US 285· Alamo Drive/Calle Mejia· Alamo Drive/US 285· Alamo Drive/Guadalupe St

Traffic operations were evaluated using McTrans’ HCS7 software. Evaluations will include weekdayanalysis for the AM and PM peak hours for the following traffic conditions:

· Existing / Viento Drive Open (2020)· Proposed / Viento Drive Closed (2020)· Future / Viento Drive Open (2040)· Future/ Viento Drive Closed (2040)

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Figure 1 - Study Area

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2 EXISTING AREA CHARACTERISTICS

2.1 GENERAL AREA CHARACTERISTICSThe study location is located on the north side of Santa Fe, NM, just south of the interchange betweenNM 599 and US 285. The area is suburban with a mixture of residential and commercial developments.The existing Viento Drive intersection with US 285 primarily provides access to the Los PiñonesApartment Homes and the Reserve at Santa Fe Condominium Complex. The intersection is right-in/right-out onto southbound US 285 and does not have a deceleration lane from US 285 (some vehicles wereobserved partially using the shoulder to decelerate).

US 285 is a principal arterial throughout the study area with a speed limit of 45 MPH. North GuadalupeStreet is also a four-lane divided principal arterial with a speed limit of 35 MPH, both north and south ofAlamo Drive. North of Alamo Drive it is a four-lane divided rural arterial; south of Alamo Drive it is a six-lane divided urban arterial. Alamo Drive is a two-lane undivided, major collector with an assumed speedlimit of 25 MPH (there are multiple 20 MPH warning speed signs, but no posted speed limit signs alongthe roadway). Viento Drive and Calle Mejia are both two-lane local roads with speed limits of 25 MPH.

There is a traffic signal at the intersection of US 285 and Alamo Drive. The AM and PM peak periodshave cycle lengths of 110 seconds. The southbound left-turn onto Alamo Drive is prohibited and thenorthbound left-turn onto Alamo Drive is protected-permitted with a flashing yellow left-arrow. The otherintersections in the study area are two-way stop controlled, with the more minor street traffic yielding tothe traffic along the more major roadway.

2.2 EXISTING TRAFFIC VOLUMESWeekday traffic counts were collected by Mike Henderson Consulting, LLC on Thursday, February 6,2020 at the study intersection. The weather was mostly sunny with no precipitation. In addition to 12-hourturning movement counts at all study intersections, an Origin-Destination (O-D) study was performed todocument the percentage of vehicles that headed south along US 285 vs N. Guadalupe Street afterturning right onto US 285 from Viento Drive. This data was collected to aide in the redistribution of trafficin the condition where the intersection is closed. The 2020 traffic counts and the O-D study counts can beseen in Appendix A. The existing conditions peak hour volumes can be seen on Figure 2 below.

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Figure 2 - Existing Conditions (2020) Peak Hour AM (PM) Volumes

The peak hour volumes from the O-D study are summarized below in Table 1.Table 1 - Distribution of Vehicles that Turned Right from Eastbound Viento Drive onto Southbound US 285

Peak PeriodVehicles Turning Right onViento to SB St Francis Dr

Same Vehicles DivergingLeft to SB Guadalupe St

Vehicle Count Percentage Vehicle Count PercentageAM Peak (8:30-9:30 AM) 28 64% 16 36%

PM Peak (5-6 PM) 24 67% 12 33%

2.3 FIELD OBSERVATIONSField observations were performed on Thursday, February 20, 2020. The weather was cloudy in themorning and clear in the afternoon with no precipitation.

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AM OBSERVATIONS (7:00-8:30 AM):

Traffic operations were smooth throughout the entire AM peak period, with no significant delaysobserved. All of the approaches at Alamo Dr/US 285 easily cleared within one traffic signal cycle. Most ofthe traffic in the network was travelling north/south along US 285 or N. Guadalupe Street, which muchlower side-street volumes along Alamo Drive and Calle Mejia.

The southbound left-turn from Calle Mejia onto Alamo Drive did not develop a queue beyond threevehicles and all of the vehicles seemed to be able to make the movement without difficulty/significantdelay. The distance between the Calle Mejia/Alamo Drive and Alamo Drive/US 285 intersections is 150-feet, centerline to centerline. This meant that the eastbound queued vehicles (typically three to fourvehicles) occasionally queued past the Calle Mejia intersection. This did not pose an observable impactto operations, however with the increase on demand for both movements in the future, the proximity ofthe intersections might lead to some delays as vehicles are blocked from turning left at Calle Mejia/AlamoDr due to the eastbound queues at Alamo Drive/US 285.

There are some significant vertical grades throughout the re-distribution network, but the turning sightdistances do not seem to be impacted. It was difficult to find gaps in traffic to cross Guadalupe Street onAlamo Drive during the peak 15 minutes, but there were plenty of gaps during other parts of the peakhour.

The is no deceleration lane onto Viento Drive from southbound US 285, which necessitated deceleratingpartially in the southbound US 285 through lane and partially on the shoulder. Available gaps to turn rightfrom Viento Drive onto US 285 southbound were difficult to find during the duration of the peak period dueto the speed and volume of the oncoming traffic.

US 285 from W. San Mateo Road to Alta Vista Street was closed in both directions during the AM peakby the police. This could have disrupted traffic patterns but was far enough south that the impacts werelikely minimal. The closure was open by the PM peak.

PM OBSERVATIONS (4:15-5:30 PM):

Traffic operations were smooth throughout much of the PM peak, with congestion only observable duringone/two cycles during the peak 15 minutes. The arrival type varied for the northbound approach at US285/Alamo Drive between traffic signal cycles with traffic arriving on green during some cycles and justafter the light turned red during other cycles. All the approaches cleared within one cycle length. Therewas one cycle where eight vehicles arrived at the southbound left-turn from Calle Mejia onto Alamo Driveand not all the vehicles were able to turn onto Alamo Drive and make the next cycle at US 285/AlamoDrive. However, they were all able to clear the intersection during the following cycle.

One pedestrian and one bicyclist were observed traveling north along Calle Mejia. Two pedestrians wereobserved to cross US 285 at the Alamo Drive intersection and continue east along the dirt path that runsparallel to Alamo Drive. Additionally, there are NMDOT Park and Ride buses that travel through the studyarea but were not observed to impact operations.

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At the intersection of Guadalupe Street/Alamo Drive, no significant queues were observed. However, itwas difficult to turn left or go straight across the intersection along Alamo Drive due to the heavy trafficalong Guadalupe Street during the peak period. The longest queue observed along eastbound AlamoDrive was four cars turning right – the queue cleared quickly. The northbound left-turn onto westboundAlamo Drive is a bit awkward due to the lack of a striped left-turn lane (there is space for vehicles toqueue, but it is not separated by striping from the northbound through lane).

2.4 COLLISION ANALYSISSTUDY AREA CRASH PATTERNSFive years of the most recent crash data available (2014-2018) were pulled from the UNM StatewideCrash Database for the study area to determine if there were historical crash patterns that might point toa safety concern in the study area – specifically one that might be exasperated by the additional trafficturning at the US 285/Alamo Drive and Guadalupe Street/Alamo Drive intersections. Below is a summaryof the crash data. Crash reports and specific details much beyond type, severity, and collision type werenot available. The crash data was also limited to crashes that were reported. The limitations in the datamade it infeasible to create a crash diagram. The number, type, severity, crash rates, and other pertinentstatistics are summarized in the sections below. Additionally, there were no fatalities in the study. Thedetailed crash data can be seen in Appendix B.

2.4.1 INTERSECTION CRASHES

The top contributing factors for the study intersection crashes are shown in the table below.Table 2 - Study Intersection Top Contributing Factors

Top Contributing FactorIntersection

TotalsAlamo Dr -

US 285Alamo Dr -

N. Guadalupe StAlamo Dr -Calle Meija

US 285 -Viento Dr

Total Injury Total PDO Injury PDO Injury PDO Injury PDO Injury PDOFailed to Yield ROW 8 11 1 2 6 4 - 4 1 1Following Too Closely 6 10 4 7 - 2 - - 2 1Excessive Speed 6 2 4 2 2 - - - - -Driver Inattention 4 6 3 5 - 1 1 - - -Alcohol/Drug Involved 4 2 4 2 - - - - - -Other Improper Driving 4 2 4 2 - - - - - -Disregarded Traffic Signal 3 3 2 3 1 - - - - -Inadequate Brakes 2 - 1 - - - - - 1 -Improper Overtaking 1 1 - 1 1 - - - - -Passed Stop Sign 1 - 1 - - - - - -None - 5 - 5 - - - - - -Made Improper Turn - 3 - 1 - 1 - 1 - -Improper Lane Change - 2 - 2 - - - - - -Avoid No Contact - Vehicle - 1 - 1 - - - - - -

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Speeding - 1 - 1 - - - - - -Improper Backing - 1 - - - - - 1 - -Passed Stop Sign - 1 - - - - - - - 1

Totals 39 51 24 34 10 8 1 6 4 3

The top contributing factors in the table above show crashes that were mostly contributed to variousdriver errors. The crashes at the US 285/Viento Drive intersection will no longer be a concern once VientoDrive is closed. The traffic will be re-routed to the other three intersections listed above and will increasethe turning volumes at those intersections. The top contributing factor at the Alamo Drive/N. GuadalupeStreet intersection is “Failure to Yield Right of Way,” which is likely the cause of most of the crashesinvolving turning vehicles from Alamo Drive onto N. Guadalupe Street. These crashes might increase,since about half of the traffic re-routed due to the Viento Drive closure would be added at this intersectionas eastbound right-turning vehicles, leading to an increase in vehicles needing to yield the right-of-way forsouthbound traffic along N. Guadalupe Street.

The eastbound right-turn and southbound right-turn movements are the two movements at AlamoDrive/US 285 that will see increases in volume with the closure of Viento Drive. The volume increase atthe southbound right-turn movement might contribute to an increase in rear-ends due to “Following TooClosely,” “Driver Inattention,” and “Excessive Speed” having been identified as contributing crash factorsat this intersection. The top contributing factor at the Calle Mejia/Alamo Drive intersection was “Failed toYield Right of Way,” which is a contributing factor likely to result in an increase in turning crashes as morevehicles use this intersection.

2.4.2 CORRIDOR CRASHES

SB US 285 Diverge to N Guadalupe Street:· 15 crashes (No Fatalities, 4 Injury, and 11 PDO)

NB US 285 Merge from N Guadalupe Street:· 6 crashes (No Fatalities, No Injuries, and 6 PDO)

SB US 285 (NM 599 to Viento Drive):· 1 crash (No Fatalities, No Injury, 1 PDO)

SB US 285 (Viento Dr to Alamo Drive):· 1 Crash (No Fatalities, No Injury, 1 PDO)

Calle Mejia (Viento Dr to Alamo Drive):· 1 Crash (No Fatalities, No Injury, 1 PDO)

For all the corridors shown above, there were no identifiable crash patterns. The top contributing factorsvaried widely for all the corridors, with no more than four of the same top contributing factors across fiveyears of data (the top contributing factors were “Driver Inattention” and “None”). SB US 285 (north andsouth of Viento Drive) only had 2 crashes that were not related to the merge/diverge with N. GuadalupeStreet.

The closure of Viento Drive will remove traffic diverging at SB US 285 to N Guadalupe Street,theoretically making this movement safer by removing volume and weaving traffic. There will be additional

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traffic along Calle Mejia from Viento Drive to Alamo Drive and along Alamo Drive from Calle Mejia to N.Guadalupe Drive; However, there was a total of one crash along both corridors combined during the fiveyears of data analyzed. Therefore, there are no historical crash patterns along these corridors that pointto a likely safety concern that would be increased by the additional re-routed traffic.

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3 FUTURE VOLUMES

3.1 2040 FORECASTS

The existing volumes were grown to 2040 using outputs from the Santa Fe MPO’s RegionalTransportation Model, the existing 2020 volumes, and the FRATAR Methodology (Appendix C). Aminimum growth rate of 1% was assumed, so no negative growth rates were used. The forecasted AM(PM) volumes for 2040 are shown below in Figure 3.

Figure 3 - Future Conditions with Viento Drive Open (2040) Peak Hour AM (PM) Volumes

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4 PROPOSED CONDITIONS

4.1 RE-DISTRIBUTION OF TRAFFIC WITH PROPOSED CLOSURE OF VIENTO DRIVE

To model the operational impacts of closing the Viento Drive access to US 285 southbound, the vehiclesthat use that access point during the peak hours were re-routed through the network as shown in Figure4. The O-D study used to determine the percentage of vehicles that headed south along N Guadalupe Stvs US 285 after turning right onto US 285 from Viento Drive was about 50/50. The exact percentageduring the AM/PM peak hours was used to help re-distribute the volumes through the network. Figure 4shows the volumes added and subtracted from various movements throughout the system.

Figure 4 - Re-Distribution of 2020 Volumes through the Network due to the Viento Drive Closure in the AM(PM) Peak Hours

In addition to the 2020 volumes, the volumes forecasted to use the Viento Drive access point in 2040were also re-routed through the system. Figure 5 shows the volumes added and subtracted from variousmovements throughout the system.

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Figure 5 - Re-Distribution of 2040 Volumes through the Network due to the Viento Drive Closure in the AM(PM) Peak Hours

4.2 PROPOSED CONDITIONS VOLUMESThe 2020 network volumes with the re-routed traffic shown in Figure 6. The 2040 network volumes with2040 re-routed volumes are shown in Figure 7.

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Figure 6 - 2020 Conditions with Viento Drive Closed Peak Hour AM (PM) Volumes

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Figure 7 - 2040 Conditions with Viento Drive Closed Peak Hour AM (PM) Volumes

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5 OPERATIONS ANALYSISAn analysis of the existing and proposed conditions was performed to evaluate the operational impacts ofthe re-routed traffic due to the closure of the Viento Drive access to US 285.

Intersection operational performance is measured using Level of Service (LOS). LOS is a trafficengineering term used to indicate how effective an intersection serves vehicular traffic. LOS is describedby a letter designation ranging from “A” to “F” with each letter representing the amount of average delay(measured in seconds) encountered by motorists at the intersection. LOS A represents traffic conditionswith minimal delay, whereas LOS F describes traffic conditions with significant congestion and longdelays. LOS is calculated for the overall intersection and for each specific movement within theintersection. For intersections in developed areas, LOS C or better is a reasonable expectation for theoverall intersection and each movement should provide for LOS C or better as well. The metrics used inthe HCM 6th Edition to define LOS for unsignalized intersections and signalized intersections are shown inTable 3 and Table 4 respectively.

Table 3 - Level of Service Definitions for Unsignalized Intersections (HCM 6th Edition)

Table 4 - Level of Service Definitions for Signalized Intersections (HCM 6th Edition)

The traffic operations analysis was completed using McTrans HCS7. The software is HCM compliant anduses the specific intersection lane configurations, traffic volumes, traffic vehicle classifications, and othersite-specific criteria. The analysis outputs include delay and LOS for each movement. The results of theanalysis are discussed in the sections below and the output flies are included in Appendix D.

Note – The existing signal timings were used for the 2020 analysis, but the signal timings were optimizedfor 2040 conditions (the traffic signal will be re-optimized before 2040 regardless to account for changesin demand). This led to some movements showing less delay in 2040 despite heavier future volumes. The

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2040 optimized signal timings were held constant for both 2040 scenarios so the differences in delay areonly reflective of the differences in volumes.

5.1 AM PEAK HOUR OPERATIONAL ANALYSISThe operational impact of the re-routed traffic on the study intersections is shown in the tables below forthe AM peak hour.Table 5 - AM Peak Hour Operational Analysis of US 285 at Alamo Drive

Approach Movement2020

(Existing)2020

(Viento Dr Closed)2040

(Viento Dr Open)2040

(Viento Dr Closed)Delay (s) LOS Delay (s) LOS Delay (s) LOS Delay (s) LOS

EB T 52.3 D 53.6 D 46.7 D 44.9 DR 39.9 D 39.8 D 36.3 D 35.8 D

WB T 39.2 D 38.0 D 36.9 D 35.1 D

NBL 66.8 E 66.8 E 67.1 E 67.1 ET 1.2 A 1.6 A 2.4 A 3.2 AR 1.0 A 1.3 A 2.0 A 2.7 A

SB T 12.5 B 13.3 B 15.4 B 16.7 BR 8.1 A 8.8 A 9.8 A 11.0 B

Table 6 - AM Peak Hour Operational Analysis of Alamo Drive at Calle Mejia


(Existing)2020




EB L 7.5 A 7.5 A 7.5 A 7.6 ASB LR 10.0 B 10.5 B 10.2 B 10.9 B

Table 7 - AM Peak Hour Operational Analysis of Alamo Drive at Guadalupe Street


(Existing)2020




EB T 22.4 C 23.0 C 24.6 C 25.6 D

WB L 23.9 C 25.0 D 25.9 D 27.9 DR - - - - 9.2 A 9.2 A

NB L 11.9 B 11.7 B 12.1 B 11.9 BSB L 7.8 A 7.8 A 7.8 A 7.8 A

The level of service for the movements shown above varied only minimally with the re-routed volumes.The tables below show the changes that resulted from the re-routed volumes through the network in both2020 and in 2040. The largest change in delay was only by 1.8 seconds and that was a decrease indelay. The largest increase in delay during the AM peak was only 1.3 seconds.

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Table 8 – Change in Delay (seconds) with the closure of Viento Drive (US 285 at Alamo Drive)Approach Movement 2020 2040

EB T 1.3 -1.8R -0.1 -0.5

WB T -1.2 -1.8

NBL 0 0T 0.4 0.8R 0.3 0.7

SB T 0.8 1.3R 0.7 1.2

Table 9 - Change in Delay (seconds) with the closure of Viento Drive (Alamo Drive at Calle Mejia)Approach Movement 2020 2040

EB L 0 0.1SB LR 0.5 0.7

Table 10 - Change in Delay (seconds) with the closure of Viento Drive (Guadalupe Street at Alamo Drive)Approach Movement 2020 2040

EB T 0.6 1

WB L 1.1 2R - 0

NB L -0.2 -0.2SB L 0 0

The tables above show that the AM peak hour operational impacts of closing Viento Drive are very small,with some movements seeing a decrease in delay under both 2020 and 2040 conditions.

5.2 PM PEAK HOUR OPERATIONAL ANALYSISThe operational impact of the re-routed traffic on the study intersections is shown in the tables below forthe PM peak hour.

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Table 11 - PM Peak Hour Operational Analysis of US 285 at Alamo Drive


(Existing)2020




EB T 48.6 D 48.7 D 40.1 D 40.6 DR 38.2 D 38.5 D 21.4 C 21.7 C

WB T 45.3 D 44.1 D 37.7 D 37.3 D

NBL 58.1 E 58.2 E 56.9 E 56.9 ET 2.4 A 2.8 A 20.8 C 21.3 CR 1.0 A 1.3 A 9.4 A 9.6 A

SB T 17.1 B 17.6 B 50.9 D 49.4 DR 11.0 B 12.0 B 24.9 C 26.7 C

Table 12 - PM Peak Hour Operational Analysis of Alamo Drive at Calle Mejia


(Existing)2020




EB L 7.9 A 8.1 A 8.4 A 8.7 ASB LR 11.7 B 12.7 B 13.7 B 15.7 C

Table 13 - PM Peak Hour Operational Analysis of Guadalupe Street at Alamo Drive


(Existing)2020




EB T 17.8 C 17.5 C - - - -

WB L 34.6 D 34.7 D - - - -R 11.8 B 11.8 B 13.3 B 13.3 B

NB L 9.1 A 9.0 A 10.8 B 10.6 BSB L 10.0 A 10.0 A 11.4 B 11.4 B

The level of service for the movements shown above varied only minimally with the re-routed volumes.The tables below show the changes that resulted from the re-routed volumes through the network in both2020 and in 2040. The largest increase in delay during the PM peak was only 2.0 seconds.

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Table 14 – PM Peak: Change in Delay (seconds) with the closure of Viento Drive (US 285 at Alamo Drive)Approach Movement 2020 2040

EB T 0.1 0.5R 0.3 0.3

WB T -1.2 -0.4

NBL 0.1 0T 0.4 0.5R 0.3 0.2

SB T 0.5 -1.5R 1 1.8

Table 15 - PM Peak: Change in Delay (seconds) with closure of Viento Drive (Alamo Drive at Calle Mejia)Approach Movement 2020 2040

EB L 0.2 0.3SB LR 1.0 2.0

Table 16 - PM Peak: Change in Delay (seconds) with closure of Viento Drive (Guadalupe Street at AlamoDrive)

Approach Movement 2020 2040EB T -0.3 -

WB L 0.1 -R 0 0

NB L -0.1 -0.2SB L 0 0

Both the AM and the PM peak periods showed negligible operational impacts with the closure of theViento Drive access to US 285.

5.3 US 285/ALAMO DRIVE EASTBOUND QUEUE IMPACTSBeyond the delay impacts at the analyzed intersections, the impact of the re-routed traffic on queuelengths was also analyzed. Of the impacted movements, the only queue length increases likely to impactoperations are the eastbound queues at the US 285/Alamo Drive intersection. This is due to the proximityof the Calle Mejia/Alamo Drive intersection to the US 285/Alamo Drive intersection (along Alamo Drive, itis 90-feet from the eastbound stop bar at US 285 to the centerline of Calle Mejia). The eastbound queuesare summarized below both with Viento Drive open and then with it closed.

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Table 17 - 90th Percentile Eastbound Queue Lengths (feet) at US 285/Alamo Drive

AM PM2020 2040 2020 2040

Approach Movement OPEN CLOSED OPEN CLOSED OPEN CLOSED OPEN CLOSED

EB Thru 210.5 230.5 214.9 231.1 190.9 204.3 210.4 228.4Right 84.4 117.6 90.1 130.7 43.2 74.3 39.8 63.5

AM PM2020 2040 2020 2040

Approach Movement OPEN CLOSED OPEN CLOSED OPEN CLOSED OPEN CLOSED

EB Thru 210.5 231.0 214.9 236.6 190.9 204.6 210.4 234.1Right 84.4 97.7 90.1 115.9 43.2 58.4 39.8 58.3

The queue lengths are not significantly impacted by the re-routed traffic, with increases of ~15-20 feet(~10%) for the thru traffic. However, the existing conditions 90th percentile queues already extend past theCalle Mejia intersection, blocking the southbound left-turning vehicles. This was observed a few timesduring the peak observations and did not result in a significant impact to operations. The increase inqueue lengths is likely to result in an impact to delays, however, these delays are not able to be quantifiedusing an equation-based software such as HCS7.

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6 HIGHWAY SAFETY MANUAL ANALYSIS

This study uses version 15.0.0 of the FHWA’s Interactive Highway Safety Design Model (IHSDM)software to implement the predictive methodology of the 2010 Highway Safety Manual (1st Ed.) for thestudy area. The analysis considers US 285 and North Guadalupe Street and their intersections withAlamo Drive as well as the intersection of US 285 and Viento Drive. Historical ADTs from 2014-2018 wereused as model input and IHSDM crash predictions were compared to historical crash data from 2014-2018. An analysis was performed for the study area under both existing geometric conditions and with theclosure of Viento Drive and the subsequent re-routing of traffic. The IHSDM outputs can be seen inAppendix E.

Below, Tables 18-21 compare historic crashes to model predictions for existing geometric conditions(Viento Dr. Open), and the proposed geometric conditions (Viento Dr. Closed). The far-right column in thefour tables shows the change in predicted crashes with the closure of Viento Drive. There is an increasein predicted crashes at the intersections of Alamo Drive & US 285 and Alamo Drive & North GuadalupeStreet, but a larger decrease in predicted crashes at US 285 & Viento Drive. The total change in predictedcrashes/crash rates with the closure of Viento Drive is shown as the “Total Change” below each table.

Table 18 - 2014 to 2018 Total Crashes (Actual & Predicted)

2014-2018 Actual TotalCrashes

PredictedTotal Crashes(Viento Open)

Predicted TotalCrashes

(Viento Closed)

Change in TotalPredicted Crashes

with (Viento Closure)

Alamo Dr @ US 285 58 22.263 22.774 0.511Alamo Dr @ Guadalupe St 18 4.760 5.003 0.243

US 285 @ Viento Dr* 7 6.391 0.290 -6.101Total Change: -5.347

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Table 19 - 2014 to 2018 Crash Frequency (Actual & Predicted)

2014-2018

ActualCrash

Frequency(cr/yr)

PredictedCrash

Frequency(cr/yr)

(Viento Open)

Predicted CrashFrequency

(cr/yr)(Viento Closed)

Change in CrashFrequency (cr/yr)


Alamo Dr @ US 285 11.6 4.453 4.555 0.102Alamo Dr @ Guadalupe St 3.6 0.952 1.001 0.049

US 285 @ Viento Dr* 1.4 1.278 0.058 -1.220Total Change: -1.069

Table 20 - 2014 to 2018 Fatal/Injury Crash Frequency (Actual & Predicted)

2014-2018

ActualFatal/Injury

Crash Frequency(cr/yr)

PredictedFatal/Injury CrashFrequency (cr/yr)

(Viento Open)

PredictedFatal/Injury CrashFrequency (cr/yr)(Viento Closed)

Change in Fatal/InjuryCrash Frequency (cr/yr)


Alamo Dr @ US 285 4.8 1.5168 1.55 0.033Alamo Dr @ Guadalupe St 2 0.3275 0.3465 0.019


Table 21 - 2014 to 2018 Property Damage Only (PDO) Crash Frequency (Actual & Predicted)

2014-2018

Actual PDOCrash

Frequency(cr/yr)

Predicted PDOCrash Frequency

(cr/yr)(Viento Open)

Predicted PDOCrash Frequency

(cr/yr)(Viento Closed)

Change in PDOCrash Frequency

(cr/yr) with(Viento Closure)

Alamo Dr @ US 285 6.8 2.9357 3.0047 0.069Alamo Dr @ Guadalupe St 1.6 0.6245 0.6543 0.030


Over the five years considered, both intersections with Alamo Drive show increased incidence of crashesdue to the closure of Viento Drive. However, the closure produces a larger decrease in crashes at theintersection of Viento Drive and US 285 that outweighs the increase at Alamo Drive. This results in anoverall total decrease of 5.347 crashes in the study area over the five-year period if Viento Drive isclosed. This overall reduction is reflected in a lower frequency of all types of crashes.

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7 CONCLUSION

7.1 CONCLUSIONSThe AM/PM 2020 and 2040 operational impacts of closing the Viento Drive access point to US 285 arenegligible. The identifiable crash patterns that exist throughout the study area are ones likely to be seenin locations with high traffic volumes and the small volume of re-routed traffic is not likely to make asignificant impact. The eastbound through/right volumes at Alamo Drive/US 285 might queue past theintersection with Calle Mejia, however, this occasionally happened during field observations andoperations did not seem to be significantly impacted. Additionally, the HSM model showed an overallreduction in predicted crashes in the study area with the closure of the Viento Drive access along US 285.

operational and safety impacts of closing the ......2020/05/26 · traffic operations were...

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