aed feasibility study final

Alternatives Analysis

Bicycle & Pedestrian Crossing of the Mystic River

Somerville, Everett Massachusetts

Prepared for Exelon New England Holdings LLC and

Massachusetts Department of Conservation & Recreation

Prepared by VHB/Vanasse Hangen Brustlin, Inc. Watertown, Massachusetts

June 2009

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Table of Contents

Executive Summary ............................................................................................................... 1

Project Background and Need ................................................................................................... 1 Project Purpose ......................................................................................................................... 1 Recommendation ....................................................................................................................... 2

Existing Conditions ............................................................................................................... 3

Project Area ............................................................................................................................... 3

Amelia Earhart Dam and Operations ......................................................................... 3

Shared Use Path Alternatives .............................................................................................. 6

Design Criteria ........................................................................................................................... 6 Alternatives Analysis Evaluation Criteria ................................................................................... 6 Overview of Proposed Mystic River Crossing Alternatives ........................................................ 8

Alternative 1 Modify Access Roadway, Dam and Lock Gates for a Shared-Use

Path ............................................................................................................................ 8

Alternative 2 Construct a New Fixed-Span Shared-Use Path Bridge on New

Location ..................................................................................................................... 8

Alternative 3 Construct a New Movable Span Shared-Use Path Bridge ................ 9

Alternative 4 Modify the Existing MBTA Bridge to Accommodate a Shared-Use

Path ............................................................................................................................ 9

Crossing Alternatives Descriptions ............................................................................................ 9

Alternative 1 Modify Access Roadway, Dam and Lock Gates for a Shared-Use

Path ............................................................................................................................ 9

Other Required Modifications/Impacts ..................................................................... 10

Criteria Evaluation .................................................................................................... 10

Alternative 2 Construct a New Fixed-Span Shared-Use Path Bridge on New

Location ................................................................................................................... 13


Alternative 3 Construct a New Movable Span Shared-Use Path Bridge .............. 16


Alternative 4 Modify the Existing MBTA Bridge to Accommodate a Shared-Use

Path .......................................................................................................................... 18


Construction Cost Summary ............................................................................................ 221

Conclusion ............................................................................................................................ 12

Criteria Summary ..................................................................................................................... 12

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Attachments

Attachment A: Design Criteria Attachment B: PowerPoint Presentation Attachment C: Cost Estimate

List of Figures

Figure No. Description

1 Project Locus

2 Bostons Alternative Transportation Network

3 General Study Area

4 Alternative 1 Modify Access Road, Dam & Gates

5 Alternative 1 Proposed Cross Section A-A

6 Alternative 2 New Fixed-Span Bridge Structure

7 Alternative 3 New Movable Span Bridge

8 Alternative 4 Modify MTBA Bridge

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\\vhb\archives\Watertown\Projects\TE\09639.00\reports\AED Feasibility Study Final.doc 1 Executive Summary

Executive Summary

Project Background and Need

The Cities of Everett and Somerville have taken several initiatives to revitalize

sections of their communities from abandoned mills and chemical plants, to create

bustling retail, commercial and manufacturing areas, as well as vast stretches of open

spaces along the Mystic River. As such, the City of Everett completed the Everett

Waterfront Assessment Report in June 2003. This report evaluated the current land

use along the Mystic River and prepared a recommended plan for future land use.

The Case Statement for Active Transportation for the Mystic River Communities by Mystic

Valley Active and Safe Transportation Network (Mystic VAST-Net) notes that the

Mystic River watershed has several existing bicycle/pedestrian facilities as well as

numerous planned facilities. In addition the communities of Cambridge and

Somerville are the hubs of several former railroad corridors which have been

converted or are under consideration for conversion to bicycle/pedestrian shared-

use trails. Part of the initiative noted above is to link the current and future green

spaces along the Mystic River in Everett to the existing green spaces in Somerville, on

the other side of the river.

Unfortunately these facilities are not well connected. A key link that is missing is the

actual connection from Everett to Somerville. Mystic VAST-Net also notes that the

Mystic River and regional roadway system serve as significant barriers to bicycle

travel in the communities along the river.

Project Purpose

The Department of Conservation and Recreation (DCR), in cooperation with Exelon

New England Holdings, LLC are evaluating the feasibility of providing a bicycle and

pedestrian crossing over the Mystic River in the vicinity of the Amelia Earhart Dam,

located in Somerville and Everett, Massachusetts (See Figure 1). In addition, in

cooperation with the MBTA, DCR is also preparing conceptual design plans to

extend the Draw 7 Park bike path through the MBTAs Charlestown Bus

Maintenance Facility, to Route 99 in Everett, MA.


Insert Figure 1 (remove page)


The purpose of this analysis is to evaluate the feasibility of constructing a continuous

bicycle and pedestrian shared-use path over the Mystic River in the area of the

Amelia Earhart Dam between the communities of Somerville and Everett. This

crossing would connect several existing and proposed shared-use paths including

the Path-to-the-Sea, the Somerville Community Path and existing/proposed trails

along the banks of the Mystic River (Mystic Way). In turn these connections would

link to other regional paths including the Minuteman Commuter Bikepath to the

northwest, the proposed Mass Central Rail Trail heading west, the Paul Dudley

White Path along the Charles River and the Southwest Corridor Park. See Figure 2

for general location of other trails.

The project objective of this study is to identify and evaluate alternatives for a

pedestrian and bicycle crossing of the Mystic River in the area of the Amelia Earhart

Dam, and to advance the design of two of the missing links of the regional bike path

in the Lower Mystic River Basin.

Recommendation

Alternatives analyzed in this report to provide a bicycle and pedestrian crossing of

the Mystic River include:

A path over the lock gates;

A movable span bridge over the locks;

A new bridge upstream from the dam; and

Attaching a structure to the existing MBTA bridge.

The alternatives that utilize the dam or portions of the dam present significant

operational conflicts between the functions of the structure as a flood control and

navigation structure versus bicycle/pedestrian transportation. The cost of the new

structure alternative or the alternative utilizing the existing MBTA bridge is

expensive and requires construction of a new structure.

None of the alternatives analyzed in this study were found to be practical, feasible, or

within reasonable cost. We recommend that proponents work with the adjacent

communities and the Massachusetts Highway Department to modify the existing

roadway bridges and approaches (Route 99/Alford Street south of the dam, Route

28/Fellsway Bridge north of the dam) to provide the pedestrian and bicycle crossing

over the Mystic River as these structures are more readily adaptable to provide

bicycle and pedestrian transportation. It is our understanding that the Route 99

bridge is currently in design for replacement of the superstructure at its current

locations.

\\vhb\archives\Watertown\Projects\TE\09639.00\reports\AED Feasibility Study Final.doc 3 Existing Conditions

Existing Conditions

Project Area

The Mystic River extends from Boston Harbor to the south and forms the southern

and southwestern boundary of Everett with the cities of Boston, Somerville and a

small portion of Medford. The river is tidal up to the Amelia Earhart Dam and non-

tidal thereafter. The physical character of the river varies greatly along its 12.5 mile

length. It progresses from a predominantly meandering, natural and pastoral

landscape in its northern reaches to a commercial and industrial landscape near the

project area. The degree of pedestrian and vehicular access to the water varies along

the rivers length and connections between these access points are discontinuous

within the project area.

The general study area is the Mystic River crossing bordered to the west by Draw 7

Park in Somerville and the Gateway Plaza/Mystic View Road in Everett to the east.

See Figure 3. The main element of this analysis is the Amelia Earhart Dam structure

and the adjacent waters of the Mystic River. Other existing river crossings in the

general study area include the Route 99 (Alford Street) roadway bridge to the south

(downstream)of the dam, an MBTA Orange Line bridge also south (downstream) of

the dam, an MBTA Orange Line rapid transit bridge north (upstream) of the dam

and the Route 28/Fellsway roadway bridge also located north of the dam. Another

element to crossing the Mystic River in the general project area is the implementation

of an extension of the path in Draw 7 Park south under the MBTA RR and through

an MBTA bus maintenance facility. That element is the subject of a separate

feasibility study.

Amelia Earhart Dam and Operations

The Amelia Earhart Dam spans the Mystic River from Somerville to the west and

Everett to the East. The Army Corps of Engineers and the MDC constructed the dam

in the 1960s to address upstream flooding problems and eliminate tidal influence. In

the mid 70s a pumping station was added to the dam. Several large diesel powered

pumps conveying approximately 4000 cubic feet per second are used to pump river

water against high tide.


Several boat launch ramps and docking facilities are located on both sides of the river

immediately upstream from the dam.

There are three locks in the dam. Two of the locks are 120 feet long by 22 feet wide

with one large lock that is 325 feet long by 45 feet wide.

According to the MDC records at the dam, a maximum of approximately 50 vessels

per month pass through the locks during the winter off-peak boating season and

approximately 3,300 vessels per month pass through the locks during the peak

boating season in the summer and fall. The time to move vessels through the locks

varies from 1 to 10 minutes depending upon the level of the water downstream of the

locks.

The dam is staffed around the clock throughout the year to operate the locks. All

three locks are used. The two smaller locks are primarily used for recreational small

boat traffic while the larger lock is primarily used for larger boats and flood control.

Combining the lock openings for boat traffic and flood control results in an estimated

number of openings of over 5,000 times a year, but primarily concentrated in the

summer months. In addition to the number of lock openings, the duration of time of

each opening is important as operators must be physically present at the controls for

short term opening/closings. During flood control, the main lock can remain open

anywhere from 30 minutes to several hours.

The dam consists of an earthen embankment extending out from the river banks to a

cement concrete structure near the dam locks and control buildings at the centerline

of the main river channel.


A 24-foot wide paved access roadway

leads to a control/maintenance

building and three lock structures.

Public access to the dam facilities is

restricted by a series of chain link

fence and gates across the access road.

Dam staff access is provided via 3-foot

wide metal grated walkways on top of

the lock gates. The walkways along

the gates meet at the center of the curved lock forming a sharp angle.

The concrete deck section of the dam in the general lock area includes openings in

the concrete deck for access to the lock gate operating machinery and pumps. These

openings are covered by open metal grates which are not ADA or bicycle compatible.

Several concrete sections of the existing dam structure are in need of repair including

the existing concrete surface around the walkways which is spalling and cracked.

The controls for opening the locks are alongside the locks outside of the personnel

building on the dam level. A control tower that sits approximately 25 feet above the

top of the dam is in a state of disrepair and is closed. The lock operators are housed

in a small building at the level of the dam. For each lock opening/closing, the

operator has to walk out and manually press the controls. Because the operators are

at dam level, they have limited visibility of the dam and the approaches.

\\vhb\archives\Watertown\Projects\TE\09639.00\reports\AED Feasibility Study Final.doc 6 Shared Use Path Alternatives

Shared Use Path Alternatives

The proposed river crossing evaluated in this analysis consists of providing an

accessible bicycle and pedestrian shared-use path across the Mystic River in the

vicinity of the Amelia Earhart Dam. This section outlines the applicable design

criteria, an overview of proposed alternatives and brief discussion of impacts and

costs. A summary table is included at the end of this section.

Design Criteria

The shared-use path will need to accommodate a variety of users, including walkers,

bicyclists, joggers, persons with disabilities, skaters, for recreation, commuting and

local access. A paved shared-use path is the type of facility that can best meet the

expectations that users have for a non-motorized path in an urban area.

The primary references for the shared-use path design criteria include the 2006

Massachusetts Highway Department Project Development & Design Guide (MHD

Design Guide), 521 MCR The Rules and Regulations of the Massachusetts

Architectural Access Board, the American Association of State Highway and

Transportation Officials (AASHTO) Guide for the Development of Bicycle Facilities,

1999 edition, (AASHTO Guide), American Association of State Highway and

Transportation Officials (AASHTO) A Policy on Geometric Design of Highways and

Streets (The AASHTO Green Book) and the Manual on Uniform Traffic Control

Devices (MUTCD).

The relevant design information compiled from these references has been included in

the Attachment A, Design Criteria.

Alternatives Analysis Evaluation Criteria

The analysis and evaluation of the crossing alternatives were based on the following

criteria:

Criteria 1: Compatibility with Dam Operations and River Navigation: the intent

of the original dam design did not include provisions for access the dam by the

general public on an as-needed basis. Since the dam also functions as a flood


control devise, the impact of opening/closing the lock gates for

bicycle/pedestrian crossings on the flood control function of the dam will need

to be considered. Exposure to moving parts of the lock, strong and

unpredictable currents in and around the lock entrances could expose

unsuspecting pedestrians and bicyclists to situations where they may not be able

to react accordingly.

Criteria 2: Right-of-Way: Path construction on privately owned land will require

some type of right-of-way (ROW) action, including temporary easements, rights-

of-entry, permanent easement, acquisition and possibly relocation.

Criteria 3: Geometrics: The available pavement width and condition (horizontal

and vertical alignments, sight distances) on the existing approaches and dam

access roadways were evaluated for compliance with design criteria.

Criteria 4: Trail Accessibility and Connections with Local Features: The trail

alignment location relative to major bicycle and pedestrian traffic generators

such as residential neighborhoods, parking lots, schools, recreational facilities

and employment centers shall figure into the evaluation scoring for this criteria.

Criteria 5: Compatibility with Local, Regional, and State Master Plans: Path

alignments that enhance and compliment the goals of various local, regional and

state master plans, park plans and are supported by local representatives shall

receive favorable scores in the evaluation process.

Criteria 6: Construction Costs: Although costs are not the sole factor in selecting

a route, the availability of funding to construct the path certainly plays a major

role in route selection and project scheduling. Costs will be calculated based on

the major known items of work required for each alternative and expressed as a

total construction cost. Costs for major structures will be listed as separate items.

The most current Mass Highway Construction Contract bid prices will be

utilized for the calculations.

Criteria 7: Grades: Long, steep profile grades on both on-road and off-road

bikeways can make bicycling difficult for some users. A profile grade of 5% will

be considered the maximum preferred grade. If this is not feasible, grades over

5% will be considered if the length of grade does not exceed 500 feet.

Criteria 8: Aesthetic and Visual Conditions: Routes that connect directly to

scenic vistas and locations of historic significance will be given a higher

evaluation score than alignments that require spur connections.

Criteria 9: Environmental/Historic Impacts: Impacts to wetlands,

floodplain/floodway or sites of historic and archaeological interest will be

considered in the project approach. Much of the Mystic River Lower basin was

polluted due to adjacent land use such as chemical plants, commercial


manufacturing and assembly plants. Today, most of these pollutants reside in

the sediment at the bottom of the river. Any proposed activities that alter or

disturb the river sediments must be planned and designed to minimize exposure

to the sediments and properly manage contaminated materials. Indeed, the

activities associated with designing this crossing must consider past activities

and define actions to meet future objectives that include swimming and other

water recreational purposes.

As a wetland resource in Massachusetts, the Mystic River is subject to a number

of state and federal environmental regulations affecting the river banks, bed of

the river, and land area adjacent to the river and any activities within or on these

areas. Any proposed work must be designed to conform to specific regulatory

standards. In particular, the project site and Mystic River include the following

coastal resource areas: Land Under the Ocean, Designated Port Area, Coastal

Banks, Banks of or Land Under Rivers that Underlie Anadromous/Catadromous

Fish Runs and Land Subject to Coastal Storm Flowage. Inland wetland resource

areas at the project site include: Bank, Land Under Water Bodies and Waterways,

Land Subject to Flooding, and Riverfront Area. Each of these coastal and inland

wetland resource areas is protected for the various functional values it provides.

The intent of the regulations is to allow development to proceed without loss of

these important environmental, social and economic values.

Overview of Proposed Mystic River Crossing Alternatives

Alternative 1 Modify Access Roadway, Dam and Lock Gates for a Shared-Use Path

Alternate 1 utilizes the existing dam structure to provide access across the Mystic

River by modifying the existing access road, and delineating a bicycle and pedestrian

path across the building and lock area. Improvements included bicycle/pedestrian

railings and structural modifications to the lock gates for a public walkway.

Alternative 2 Construct a New Fixed-Span Shared-Use Path Bridge on New Location

Alternative 2 includes an independent bicycle and pedestrian bridge spanning

approximately 840 feet across the Mystic River. The superstructure will consist of a

14 foot shared-use path with a maximum longitudinal gradient of 5%. The structure

will maintain a minimum vertical clearance of 35 feet in the vicinity of the large lock.

The clearance will require an additional three hundred feet of structure to maintain

the 5% grade down to the existing ground grade on the west side of the river.


Alternative 3 Construct a New Movable Span Shared-Use Path Bridge

Alternative 3 utilizes several hundred feet of the existing easterly dam embankment

before the path departs from the dam to a new independent bridge bypassing the

lock system. The bridge structure will utilize two movable spans to accommodate

boat traffic.

Alternative 4 Modify the Existing MBTA Bridge to Accommodate a Shared-Use Path

Alternative 4 modifies the existing MBTA commuter rail bridge substructure to

accommodate a bicycle and pedestrian section separated by a barrier from the tracks.

Crossing Alternatives Descriptions

Alternative 1 Modify Access Roadway, Dam and Lock Gates for a Shared-Use Path

Alternate 1 utilizes the existing dam structure to provide access across the Mystic

River by modifying the existing access roadway, dam and lock gates and delineating

a bicycle and pedestrian path across the operations and lock area. Refer to Figure 4.

The Alternative 1 crossing begins at the existing Draw 7 Park path and continues

along the dam access road. A separate 14 foot shared-use path will be constructed

adjacent to the existing access roadway separated by a 42 inch railing and 6 foot

fence. A portion of the existing stone revetment will be removed and a reinforced

concrete retaining wall will be constructed to support the path. Refer to Figure 5. The

pathway will continue onto the existing dam structure where it will transition from a

14-foot wide shared-use path to a 7-foot wide shared-use path. Bicyclists would be

required to dismount and walk their bicycles along the 7-foot wide path. The path on

the dam will be defined by 42 inch high railings on both sides. Gates will be provided

at both sides of each lock and open and close concurrently with the lock gates at the

walkway entrance; the users path is restricted even further by the railing placement.

These deficiencies coupled with the interface details between the walkway and dam,

grating spacing and railing details do not meet current access requirements for public

use and would not accommodate bike passage.


The recommendation for the lock crossing is to

completely remove the existing walkway

superstructure and replace it with a walkway design

similar to that used at the Charles River Dam. This

design includes a checkered plate walkway and a

galvanized steel railing system supported by steel box

beams and steel box columns connected to the top of

the sector gates. The walkway would have a clear

width of 4-6 and smoother geometry. The walkway

system and interface details with the dam structure

would be designed to meet current ADA

requirements.

The fenced walkway will continue along the dam structure to the north side of the

pumping station. The pathway will follow a layout that minimizes impacts to dam

operations and limits crossing of the steel grating and equipment tracks. The path

will transition from a 7 foot wide path to a 14 foot wide path just east of the access

ramp; the access road will be widened similar to the westerly access road to

accommodate a 14 foot shared use path. Once the path leaves the dam structure it

will continue along a circuitous route and meet up with the existing path located at

Mystic View Road.

Other Required Modifications/Impacts

As noted earlier, there are metal-grated openings in the concrete deck section of the

dam near the locks to provide access to the gate opening machinery and pumps.

Some of these openings are located in the proposed pedestrian/bicycle path. The

metal grates are not pedestrian or bicycle compatible. Some sections of the concrete

deck are in need of repair to correct surface conditions which could be hazardous to

pedestrians and bicyclists. A thorough concrete inspection/repair program to

address these hazardous surface conditions is required as part of this alternative.

Criteria Evaluation

Criteria 1: Compatibility with Dam Operations and River

Navigation

The river currents in and around the lock are swift, powerful and unpredictable

given the variables of tidal flow, river levels and lock operations. A person falling

into the river in this area could very easily and quickly become trapped by the swift

moving currents. These conditions would most likely prevent rescues and endanger

the lives of emergency responders.


The proposed path will be adjacent to the existing control panels. The control panels

will need to be secured from public access or removed to a more suitable location.

Because the operators are at dam level, they do not have full visibility of the area.

The location of the path and railing system will cause the operators visibility to be

limited even further. For the stated reasons it is recommended that the control panels

be relocated into a secure cabinet in a more desirable location providing easy access

and improved visibility.

The addition of a wider and more user friendly walkway system over the lock gates

will require modifications to the existing gate structure. The additional walkway area

will more than double the existing dead load on the gates, the existing gate structural

members will require the addition of steel plates to accommodate the additional

loading, and the extra steel will in itself add significant weight to the existing gate

system. It is anticipated that the mechanical and movable components of the gate

system will need to be further studied and most likely require upgrading.

During periods of heavy rain, or when heavy rain is forecast and typically during

periods of ebb tide the lock gates are left open in lieu of using the pumps to manage

river flow. Closing the gates to allow pedestrian or bicycle crossings during these

periods will significantly increase the number of lock open/close cycles. Conversely,

waiting times for vessels to traverse the dam may increase if they have to wait for an

opening/closing cycle of the lock to allow for bicylce and/or pedestrian crossings.

The openings for boat traffic increase in the summer months. The summer months

will also be the time when the proposed path will see its highest usage. It is not

advisable to allow public access across closed lock gates when the lock is being filled

or drained for boat passage due to the potential that a pedestrian or bicyclists could

fall into the lock and be pinned or caught in the river current. It is highly likely that

pedestrians and bicyclists wishing to cross the river will incur significant delays

while the locks are opened and closed for boat passage.

Initial discussions with the Coast Guard indicate that although the Amelia Earhart

Dam is not a designated waterfront facility, the dam falls under the Maritime

Security Act of 2002 (MTSA) and CFR Title 33 Part 107.9 and is therefore under the

Coast Guards jurisdiction for the security of the dams operations and safety.

Meeting the security requirements for the Coast Guard will simultaneously meet the

security requirements for the Department of Homeland Security. The Coast Guard

has indicated that the dam is not a critical homeland security asset and does not

require any extraordinary security measures. The Coast Guard will require measures

be put in place to restrict public access to the functioning areas of the dam such as the

lock mechanism and the control panels. Also, measures should be used to inhibit the

publics ability to interfere with watercraft navigating the river from any

walkways/paths that cross the water.


Criteria 2: Right-of-Way Impacts

It is anticipated that the improvements can be completed within existing publicly

owned property.

Criteria 3: Geometrics

The reduced path width for bicycles is a concern. Bicyclists tend to avoid stopping

unless absolutely necessary. Directions to Dismount and Walk Your Bicycle would

most likely be disregarded. It is not practical or advisable to direct bicyclists into an

area where dam/lock operators and staff may be moving unexpectedly back and

forth across the path. Likewise, it is not advisable to expect operators to focus on the

operation of the locks while at same time be on the lookout for approaching

pedestrians or bicyclists.

Criteria 4: Trail Accessibility and Connections

The trail across the dam would meet the goal of connecting the various regional trails

and provide a continuous circuit for access to the river. This alternative provides the

shortest route for crossing of the river.

Criteria 5: Compatibility with Local, Regional and State

Master Plans

The trail across the dam would also comply with the various master plans that call

for a bicycle and pedestrian crossing of the river.

Criteria 6: Construction Cost

Cost for the improvements is $5,423,000 for the modification of the roadway for the

trail approaches, installation of automatic bicycle and pedestrian gates, relocation of

the lock gate control panels and upgrade of the lock gates. The cost does not include

upgrade of the control tower building.

Criteria 7: Grades/ADA Compliance

The proposed trail grade would comply with the 5% maximum profile grade criteria

however the path surfaces would need to comply with ADA for a firm, stable and slip

resistant surface. Additional features must address the needs of sight and hearing

impaired users. It is doubtful that these needs can be incorporated into the

operational elements of the dam and locks.


Criteria 8: Aesthetic and Visual Conditions

The trail across the dam would provide access to scenic vistas and overlooks of the

river and surrounding natural areas.

Criteria 9: Environmental/Historic Impacts

Modifications to the approach roadways will require some filling and construction

activities in the river; however this work is expected to be minimal. Extraordinary

permitting requirements are not expected.

Alternative 2 Construct a New Fixed-Span Shared-Use Path Bridge on New Location

Alternative 2 provides an independent structure spanning approximately 840 feet

across the Mystic River. The superstructure will consist of a 14 foot shared path with

a maximum longitudinal gradient of 5%. The structure will maintain a minimum

vertical clearance of 35 feet in the vicinity of the large lock. Refer to Figure 6.

The new bridge would be located approximately 400 feet north of the center of the

Amelia Earhart Dam. Beginning at the west side of the Mystic River the new crossing

will be approximately 22 feet above grade and can be accessed via a stairway from

the Draw 7 Park path or from a 300 foot long ADA compliant ramp that runs parallel

to the river and ends just north of the dam access road. The maximum vertical

clearance will be approximately 35 and will occur at a point between the large lock

and the most easterly of the small locks. To maintain ADA accessibility the crossing

will have a maximum gradient of 5 percent. At the east abutment the structure will

be within a couple of feet from existing grade. The existing path will be re-aligned

and regraded to connect to the bridge abutment; the 14 foot path will be terminated

at the edge of Mystic View Road. The bridge substructure will consist of concrete

piers supported on piles. The superstructure will be described by the two alternatives

listed below.

This alternative would have no impact to the dam.

Alternative 2a Concrete slab on girder

Alternative 2a consists of 8 spans with lengths from west to east of 85, 100, 100, 85,

105, 130, 130, and 105. The superstructure will consist of a reinforced concrete deck

slab with a clear width of 14 feet, supported on three 42 deep steel girders. The

substructure will consist of concrete piers supported on piles.

.


Alternative 2b Prefabricated steel girder

Alternative 2b consists of prefabricated steel trusses. The bridge will consist of 7

spans with lengths from west to east of 140, 140, 80, 120, 120, 120, and 120. The

substructure will consist of concrete piers supported on piles.

Criteria Evaluation


Navigation

The proposed bridge will introduce some restriction on manuveurability on the

upstream entrance to the large lock. No other impacts to the operation of the dam

are expected.

The construction of this facility across a navigable watercourse must be designed

with careful consideration of impact on navigation. Navigation access must be

maintained including existing height and width clearances. In this circumstance, the

downstream fixed railroad bridge that replaced Drawbridge No. 7 creates the current

minimum height clearance of approximately 35 feet. The 45-foot width of the larger

of the locks establishes the minimum width clearance. Several required permits for

this crossing include navigation as part of their review process. These include the

Section 10 permit from the U.S. Army Corps of Engineers, the Coast Guard Permit,

Coastal Zone Management Consistency, and the Chapter 91 Waterways License.



owned property.


In general, the geometrics of the proposed bridge crossing alternative would exceed

the minimum criteria with the exception that a relatively tighter radius is needed at

the bottom of the proposed ramp at Draw 7 Park to meet with the existing path.



The trail on the new bridge would meet the goal of connecting the various regional

trails and provide a continuous circuit for access to the river.


Master Plans

The trail on the new bridge would also comply with the various master plans that

call for a bicycle and pedestrian crossing of the river.


Cost for the new bridge Alternative 2A is $7,700,000 for the new bridge and

approaches. For Alternative 2B the cost is $6,100,000 for the new bridge and

approaches.



and for a surface that is firm, stable and slope resistant.


The trail on the new bridge would provide access to scenic vistas and overlooks of

the river and surrounding natural areas.


Construction of new approaches to the bridge and construction of piers in the river

will require filling and construction activities in the river. The following is a list of

the regulatory permits that will likely be needed to complete this project:

Section 10/404 permit from the U.S. Army Corps of Engineers

MA Coastal Zone Management Consistency Statement

Coast Guard Bridge permit

Section 401 Water Quality Certificate from the MADEP

Chapter 91 Waterways License from the MADEP

Order of Conditions from Somerville and Everett Conservation Commission

In addition, the easterly abutment resides on a 21E site (Monsanto site) would most

likely require off-site disposal of contaminated soil and additional mitigation

measures yet to be determined.


Alternative 3 Construct a New Movable Span Shared-Use Path Bridge

Alternative 3 uses the existing eastern dam roadway approach then diverts to a new

independent bridge over the locks and fixed spans to the west bank. See Figure 6.

The bridges over the locks would consist of two movable spans, the first being 50 feet

long and located in front of the two small locks. The second movable span is 55 feet

long and located in front of the large lock. The movable spans connect with the

existing access road to the east of the dam via three new fixed spans and to the west

bank via two new fixed spans. The total number of new spans is eight with lengths

from west to east of 155, 50, 65, 55, 143, 161, 143, & 31.The movable spans will be

the vertical lift type with a minimum vertical clearance of 35 to match the existing

vertical clearance of the existing downstream RR bridge. Refer to Figure 7.

Criteria Evaluation


Navigation

The proposed bridge will introduce some additional restriction on manuveurability

on the upstream lock entrances at the small locks due to the construction of

additional fenders to protect the new bridge piers. Other impacts to the operation of

the dam include the need for coordinating the operation of the movable bridge spans

with the lock operations to provide vertical clearance when needed. It is anticipated

that this will require at least one additional operator for the bridge.

Additionally, it is anticipated that a bridge this close to the lock should contain

provisions that decrease the likelihood of objects being dropped or thrown from the

sructures into the locks.

As with Alternative 2, the construction of this facility across a navigable watercourse

must maintain existing height and width clearances. In this circumstance, the

downstream fixed railroad bridge that replaced Drawbridge No. 7 creates the current

minimum height clearance of approximately 35 feet. The 45-foot width of the larger

of the locks establishes the minimum width clearance. Several required permits for

this crossing include navigation as part of their review process. These include the

Section 10 permit from the U.S. Army Corps of Engineers, the Coast Guard Permit,

Coastal Zone Management Consistency, and the Chapter 91 Waterways License.




owned property.






The trail on the new bridge would meet the goal of connecting the various regional



Master Plans




Cost for the improvements is $6,250,000 for the new bridge and approaches.


The proposed trail grade would comply with the 5%

maximum profile grade criteria and for a surface that is

firm, stable and slip resistant. Joints on movable span

bridges must have more play then joints on fixed span

thus movable bridge joints are not often compatible with

bicycle and pedestrian traffic. See attached photograph

of a finger joint on a movable span.

Criteria 8: Aesthetic and Visual

Conditions

The trail on the new bridge would provide access to scenic vistas and overlooks of the




Construction of new approaches to the bridge and construction of piers in the river

will require filling and construction activities in the river. The following is a list of

the regulatory permits that will likely be needed to complete this project:

Section 10/404 permit from the U.S. Army Corps of Engineers

MA Coastal Zone Management Consistency Statement

Coast Guard Bridge permit

Section 401 Water Quality Certificate from the MaDEP

Chapter 91 Waterways License from the MaDEP

Order of Conditions from Somerville and Everett Conservation Commission

Alternative 4 Modify the Existing MBTA Bridge to Accommodate a Shared-Use Path

Alternative 4 includes construction of a new shared-use path bridge from the access

road to the MBTA tracks and a shared-use path cantilevered off the side of the

existing MBTA bridge to the south of the dam. The bridge from the access road will

consist of a concrete deck slab on steel girders or a prefabricated steel truss. The

substructure will consist of concrete piers supported on piles. For the path on the

MTBA bridge a primary concern is the separation distance of the proposed path to

the active RR tracks. Experience on other rail-with-trail shared structures has shown

a minimum of 16 feet of clearance from the centerline of the tracks to the edge of the

path. Even with an AASHTO minimum path width of 8 feet, the cantilevered

structure width would be a minimum of 24 feet. This would require the MBTA

bridge undergo such major modifications that a new structure would probably be

more practical and less expensive. A major retrofit for this cantilevered structure

would require modifications for seismic loadings. Refer to Figure 8.

Criteria Evaluation

Criteria 1: Compatibility with Dam Operations and

Navigation

It is not anticipated that the proposed Alternative 4 crossing bridge will introduce

additional restriction on manuveurability on the lock entrances as the RR bridge is

located approximately 1,000 feet downstream from the dam.


As with Alternatives 2 and 3, the construction of this facility across a navigable

watercourse must maintain existing height and width clearances. In this

circumstance, the downstream fixed railroad bridge that replaced Drawbridge No. 7

creates the current minimum height clearance of approximately 35 feet. The 45-foot

width of the larger of the locks establishes the minimum width clearance. Several

required permits for this crossing include navigation as part of their review process.

These include the Section 10 permit from the U.S. Army Corps of Engineers, the

Coast Guard Permit, Coastal Zone Management Consistency, and the Chapter 91

Waterways License.


It is anticipated that the path approaches to the RR bridge will require right-of-way

actions on MBTA property. It is anticipated that the path will need to include

construction of features to prohibit public access onto the tracks.






The trail on the new bridges would meet the goal of connecting the various regional



Master Plans




Cost for the Alternative 4 is $ $6,300,000 for the new bridge and approaches.



and for a surface that is firm, stable and slip resistant.



The trail on the new bridge would provide access to scenic vistas and overlooks of the



Construction of new approaches to the bridge may require filling and construction activities in the river. The following is a list of the regulatory permits that will likely be needed to complete this project: Section 10/404 permit from the U.S. Army Corps of Engineers MA Coastal Zone Management Consistency Statement Coast Guard Bridge permit Section 401 Water Quality Certificate from the MADEP Chapter 91 Waterways License from the MADEP Order of Conditions from Somerville and Everett Conservation Commission.

Table 1: Alternative Evaluation Criteria Summary Alternative 1

Modify Access

Road & Dam

Alternative 2

New Bridge

Alternative 3

Movable Span

Alternative 4

Modify RR Bridge

Criteria 1: Dam Op & Navigation

Significant increase in lock open/closures.

Some restriction on maneuverability at lock entrance.

Some restriction on maneuverability at lock entrance. Require additional staffing to operate bridge.

No Impact.

Criteria 2: ROW None. None. None. ROW acquisition and/or easements from MBTA.

Criteria 3: Geometrics Does not meet criteria. Tight radius at Draw 7 Park.

Tight radius at Draw 7 Park.

Tight radius at Draw 7 Park.

Criteria 4: Accessibility Connections

Provides direct connection.

Provides connections. Provides connections. Provides connections.

Criteria 5: Local/Regional State Plans

Compatible with local and state plans.




Criteria 6: Cost $5.4 Mil $7.7 Mil 2A

$6.1 Mil 2B

$6.2 Mil $6.3 Mil

Criteria 7: Grades Meets regulations for grade. Potential problem for sight impaired path over locks.

Meets regulations for grades.

Meets regulations for grades. Potential problem with movable span bridge joints.

Meets regulations for grade.

Criteria 8: Aesthetic and Visual

Provides overlooks. Provides overlooks, visual impact of new structures.

Provides overlooks, visual impact of new structures.

Provides overlooks, visual impact of new structures.

Criteria 9: Environmental/Historic

Some filling in river. Some fill and new substructures in river.

Some fill and new substructures in river.

Some fill and new structures in river.

\\vhb\archives\Watertown\Projects\TE\09639.00\reports\AED Feasibility Study Final.doc 21 Construction Cost

Construction Cost Summary

The approximate construction costs for each Alternative are as follows.

Alternative 1 is approximately $5,423,000

Alternative 2a is approximately $7,700,000

Alternative 2b is approximately $6,100,000



Refer to Attachment C for a detailed cost breakdown.

22 Conclusion

Conclusion

Criteria Summary

Although all the alternatives evaluated provide connections to planned local and

regional facilities, none of the alternatives provides a practical, feasible and cost

effective solution to provide a bicycle and pedestrian crossing of the Mystic River.

Alternative 1 would locate the path on the existing dam access road and on the top

of the locks. This alternative would significantly increase the number of lock

open/close cycles especially during the peak seasonal use of the river by boats and

potential use of crossing by bicyclists and pedestrians. The geometry and path

surfaces on the dam would not meet several minimum shared-use trail design

criteria. The path alignment would also bring the public in close proximity to lock

operating machinery and dangerous river currents.

Alternative 2 is a new structure across the river independent of the dam. The design

adds an additional constraint and obstacle to river navigation. Placement of new

substructures in the river would also require substantial permitting efforts.

Alternative 3 locates the path along the existing dam access road then on a new

movable span structure independent of the locks. This alternative avoids bringing

the public close to the locks and requires less amount of substructure in the river

than Alternative 2. This alternative requires additional staff to operate and maintain

the movable span.

Alternative 4 locates the path on the existing MBTA rail bridge. This would require

extensive and expensive modifications to the existing MBTA bridge and construction

of an additional new bridge.

Given the close proximity of the other existing vehicle and pedestrian bridges in the

project area, we recommend the regional trail proponents work with communities

and appropriate state agencies to include improved bicycle and pedestrian

accommodations in any future rehabilitation or reconstruction of those structures.

Similar projects recently completed for bicycle and pedestrian accommodation on

existing bridges cost approximately $2,100 per linear foot of path on structure.

\\vhb\archives\Watertown\Projects\TE\09639.00\reports\AED Feasibility Study Final.doc Attachment A: Design Criteria

Attachment A: Design Criteria


Shared-Use Path Design Criteria

This following criteria has been developed based on standard engineering practice

and the successful application of regulatory standards and guidelines included in the

2006 Massachusetts Highway Department Project Development & Design Guide

(2006 MHD Design Guide), American with Disabilities Act (ADA) Design

Guidelines, the American Association of State Highway and Transportation Officials

(AASHTO) Guide for the Development of Bicycle Facilities, 1999 edition, (1999

AASHTO Bicycle Guidelines), American Association of State Highway and

Transportation Officials (AASHTO) A Policy on Geometric Design of Highways and

Streets (The AASHTO Green Book), Florida Department of Transportation (FDOT)

Trail Intersection Design Handbook (FDOT Trail Intersection Handbook) and the

Manual on Uniform Traffic Control Devices (MUTCD) were the primary references

for the following design criteria.

DESIGN ELEMENT CRITERIA REFERENCE

Design Speed

Paved 20mph AASHTO 1999 Bicycle Guidelines

Unpaved 15 mph AASHTO 1999 Bicycle Guidelines

Typical Section

Pavement Width 10 12 ft AASHTO 1999 Bicycle Guidelines

Shoulder Width 2 ft 2006 MHD Design Guide

Clear Zone 3 ft AASHTO 1999 Bicycle Guidelines

5 ft (side slope >3:1) 2006 MHD Design Guide

Separation from Parallel Road 5 ft AASHTO 1999 Bicycle Guidelines

Radius Horizontal Curve 100 ft with e=2% AASHTO 1999 Bicycle Guidelines

Superelevation 2% maximum AASHTO 1999 Bicycle Guidelines

Stopping Sight Distance (SSD) for Bicycles

140 ft (grade=5%)

130 ft (grade=2%)

AASHTO 1999 Bicycle Guidelines

Stopping Sight Distance (SSD) for motor vehicles

Various Exhibit 3-8 2006 MHD Design Guide

Intersection Sight Distance (ISD) for bicyclists and pedestrians crossing roadways

See Tables 8 & 9 FDOT Trail Intersection Handbook

Decision Sight Distance for motorists approaching trail crossings

Exhibit 3-9 Stop on Rural Road 2006 MHD Design Guide



Profile Grade 0.5% minimum AASHTO 1999 Bicycle Guidelines

Paved 5% maximum (ADA compliant)

Unpaved 3% maximum

Length Vertical Curve Based on SSD AASHTO 1999 Bicycle Guidelines

Vertical Grades 5% max. ADA

Vertical Clearance 8 ft minimum AASHTO 1999 Bicycle Guidelines

Railing Min. 42 height

Required for side slopes > 2:1

within 5 ft of path on a fill slope

> 10 ft high


2006 MHD Design Guide

Bridge Railing Min. 54 height 2006 MHD Design Guide

Bridge Design Load H-15 truck plus live load

ON-ROAD BIKE ROUTE (S>45 MPH AND/OR V>2000 AADT)


Curb Lane Width* 16 ft. desirable

15 ft. minimum


* Curb Lane Width = Outside Travel Lane plus Paved Usable Shoulder

(S


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\\vhb\archives\Watertown\Projects\TE\09639.00\reports\AED Feasibility Study Final.doc Attachment B: PowerPoint Presentation

Attachment B: PowerPoint Presentation

Details and costs in PowerPoint may differ from the report as these details were

updated based on public input and comment.

Project Background

This project was undertaken as part of the settlement of a federal enforcement action taken by the U.S. Environmental Protection Agency for alleged violations of the Clean Air Act.

Study Purpose

The purpose of this study is to identify feasible options for a pedestrian and bicycle friendly crossing of the Mystic River at the Amelia Earhart Dam, and to review the feasibility of extending the Draw 7 Park bike path through the MBTAs Charlestown Bus Maintenance Facility to Route 99.

Study Limits

Current Dam Operations 2 small locks, and 1 large lock Approx. 50 vessels/month pass through locks

off season, and 3,300 vessels per month pass through locks during peak season Larger lock used for flood control, and fish

passage Lock controls at dam level, limiting visibility 3 diesel powered pumps are used for flood

control during major events during high tides.

Current Dam Condition Observation tower not in service due to

poor condition

Walkways over locks are not ADA compliant

Concrete walkways are in poor shape

Current Dam Condition

Current Causeway Cross section

4 Crossing Options

Option 1 - Existing Dam Crossing Option 2 - Bridge Structure Option 3 - Lift Span over Locks Option 4 - MBTA Bridge

Option 1 Existing Dam Crossing

Proposed causeway cross section

Option 1 Advantages Utilizes existing structure to

cross river Initial cost to construct Crossing on level surface

Disadvantages Less than desirable path width

Bikes will need to be walked across portion of dam structure Congestion during peak user times

Restricted usage 30-40% down time due to lock operations Dawn to dusk restrictions

Safety and Operational concerns Maintaining separation between the dam operations and the

public Visibility for dam operators Loitering Pedestrian access limitations through lock operations Potential of vessels vandalism during lock passage

Physical Impacts major repairs to upgrade the existing dam structure for public

use. Upgrade lock mechanical systems to accommodate wider

walkway Relocate control systems to a secure location Continuous maintenance and operations Challenges meeting ADA requirements

Option 1- Construction Costs

Repair existing dam deficiencies and upgrade public use:

Upgrade Mechanical Systems:

Retrofit dam for crossing:

Total Cost

$1,500,000

$2,000,000

$1,500,000$ 5,000,000.00

Option 2 Bridge Structure

Option 2

Advantages Independent from the Dam

structure Usable through flood control Continuous 14 foot wide

shared use path Unrestricted use of the

structure Minimal long term

maintenance requirements and costs

Disadvantages Initial cost to construct 5% grades over bridge

Option 2 - Construction Costs

Prefabricated steel truss: $ 6,100,000

Option 3 Bridge w/Lift Span over Locks

Option 3

Advantages Physically separated from

the Dam lock operations Usable during flood control

operations Continuous 14 foot wide

shared use path Maintains safe separation

between public and Dam operations

Dam crossing on relatively flat surface

Disadvantages Initial cost to construct Long term maintenance

requirements and costs Long term operation costs Restricted usage

Down time during vessel passage

Dawn to dusk restrictions


Prefabricated truss and three lift spans:$6,500,000

Option 4 MBTA Bridge

Option 4

Advantages Independent from the

Dam lock operations

Minimal long term maintenance requirements and costs

Disadvantages Initial cost to construct User safety concerns due

to proximity to MBTA commuter Rail

Structural modifications to existing bridge

Constructability


For path construction only, not including modifications to existing MBTA structure$6,300,000

Concept Path Through the MBTA Yard

Existing MBTA Yard

Existing Path Alignment

Proposed Path Alignment

Existing Path Alignment

Proposed Path Alignment

Construction Costs : $620,000

Questions and Answers

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\\vhb\archives\Watertown\Projects\TE\09639.00\reports\AED Feasibility Study Final.doc Attachment C: Cost Estimate

Attachment C: Cost Estimate


Conceptual Cost Estimate - Alternative 1

Alternative 1

Description Unit Unit Cost Quantity Cost

Dam Deck Repairs & Modifications (LS) $1,250,000.00 1 $1,250,000.00

Retaining Walls (4' height) (LF) $325.00 560 $182,000.00

Full Depth Pavement (SY) $35.00 550 $19,250.00

Bituminous Concrete Walk (SY) $35.00 720 $25,200.00

Safety Rail (off Structures) (LF) $25.00 1,420 $35,500.00

Landscaping (LS) $4,000.00 1 $4,000.00

Signage (SF) $15.00 200 $3,000.00

Lock Gate Upgrades (LS) $3,000,000.00 1 $3,000,000.00

SUBTOTAL COST: $4,518,950.00

20% CONTINGENCY $903,790.00

TOTAL COST: $5,422,740.00

SAY: $5,423,000.00



Alternative 2A


Bridge Construction (LS) $5,140,000.00 1 $5,140,000.00

Ramp Construction (LS) $1,250,000.00 1 $1,250,000.00


Loam Borrow & Seed (SY) $5.00 400 $2,000.00

Signage (SF) $15.00 100 $1,500.00

Landscaping (LS) $10,000.00 1 $10,000.00


20% CONTINGENCY $1,282,800.00

TOTAL COST: $7,696,800.00

SAY: $7,700,000.00

Alternative 2B



Ramp Construction (LS) $1,250,000.00 1 $1,250,000.00



Signage (SF) $15.00 100 $1,500.00

Landscaping (LS) $10,000.00 1 $10,000.00


20% CONTINGENCY: $1,006,800.00

TOTAL COST: $6,040,800.00

SAY: $6,100,000.00



Alternative 3




Retaining Walls (4' height) (LF) $325.00 260 $84,500.00

Safety Rail (off Structures) (LF) $25.00 570 $14,250.00

Full Depth Pavement (SY) $35.00 425 $14,875


Signage (SF) $15.00 100 $1,500.00

Landscaping (LS) $10,000.00 1 $10,000.00


20% CONTINGENCY: $1,040,175.00

TOTAL COST: $6,241,050.00

SAY: $6,250,000.00



Alternative 4



Bridge Approach Construction (LS) $590,000.00 1 $590,000.00


Loam Borrow & Seed (SY) $5.00 1,800 $9,000.00

Signage (SF) $15.00 100 $1,500.00

Landscaping (LS) $10,000.00 1 $10,000.00


20% CONTINGENCY $1,047,490.00

TOTAL COST: $6,284,940.00

SAY: $6,300,000.00

aed feasibility study final

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