HomeMy WebLinkAbout1994-03-14-DAC-min.pdf frd71;14014 1
LEXINGTON DESIGN ADVISORY COMMITTEE
BIKEWAY BRIDGES
Notes of Meeting held in the offices of Massachusetts Highway Department, District 4,
Appleton Road, Arlington March 4th 1994
Present: Hubert Murray Lexington Design Advisory Committee
Bob MacDonald Massachusetts Highway Department
Andrew Wall Massachusetts Highway Department
Steven McLaughlin Massachusetts Highway Department
These notes are not intended to be an exact record but are a development of topics discussed at the
meeting with engineers from the MHD.
There are three bridges across the Minuteman Bikeway which are in poor condition and need to be
replaced. The intention is to have documents completed and out to bid by the end of September 1995
(the end of the fiscal year). The bridges in question are:
1 Maple Street, Lexington: the road crosses the Bikeway at approximately 83° The length of the
underpass would be about 43' One of the concerns is also to lower the grade of Maple Street by
approximately 4'to improve visibility and safety, especially on the approach to Mass.Ave.
2. Lowell Street, Arlington: the road crosses the Bikeway at approximately 38° The length of the
underpass is about 115'
3. Park Avenue, Arlington: the road crosses the Bikeway at approximately 121° The length of the
underpass is about 70'
MHD is concerned to keep capital and operating costs to a minimum and therefore proposed precast
concrete culverts dimensions 10' high x 12' wide. These have the advantage of:
( •quick installation
•short span (anything less than 20'does not require annual inspection)
•low capital cost
There is no set budget. Funding for the two Arlington bridges would be Federal/State ISTEA (80/20); for
the Maple Street Bridge, just State funding.
Concerns were expressed by Lexington residents regarding the long tunnel like proportions which it was
thought might generate unsafe conditions. MHD proposed lighting in the underpass to mitigate the
problem. That would be an operating cost and maintenance problem.
After review by citizens in Arlington and Lexington, MHD is considering other options:
•culverts 10'high x 18'wide(by Rotundo)
•pre-cast concrete bridge system by Con-Span with a 28' span and the possibility of stone facings
(see attached drawings).
•circular section metal culverts by Con-tech these metal culverts act as formwork for poured in
place concrete.
HM had done some research into timber bridge options and showed:
•the Vermont timber bridge competition winner now completed in Dover VT The cost of this was
roughly 50% more than the concrete alternate but could be reduced with refinement of the
details.
•West Virginia University wooden bridge designs
• Laminated Concepts wooden bridge designs
•Wheeler Timber Bridges designs
It was generally recognized in discussion that the design of these bridges over the Minuteman Bikeway
should be to a high standard in recognition of the wide constituency now served between Cambridge and
Bedford as well as the abutters in Lexington and Arlington.
Wallace, Floyd,Associates Inc.
( HM offered to report back to the Lexington Design Advisory Committee meeting on 8th March and to
develop a program and some criteria for assessing proposed options.
The following notes are based on HM's thoughts after the meeting:
To have a rational public discussion about the most desirable type of bridge, we should establish a
program and some criteria for assessing the desirability of a particular structural form.
The program for each of the bridges might include:
•roadway design loadings
•vehicular requirements-e.g. necessary crash barriers
• snowplowing requirements
•pedestrian requirements e.g. sidewalks, overlooks, seating, steps between grades
•required bikeway visibility angles
•lighting on the roadway above
•lighting in the underpass
•retention of the granite abutments as historically or architecturally significant
•range of desirable materials(e.g. granite,concrete, steel, stone facing)
Some development of the following criteria might be considered to determine the appropriate type of
stucture (steel, concrete, stone,timber) and the detailing:
•capital cost
•maintainability
•constructibility
•resistance to vandalism(fire, graffiti etc)
•safety and visibility
•aesthetics:compatibility with Bikeway as an old railroad track; with neighborhood.
Wallace, Floyd,Associates Inc.