Here are some notes from the 10th meeting of the Green Line Extension Project Advisory Group, conducted by the Executive Office of Transportation (EOT) on Monday, Dec. 1, at the St. Clement Parish Hall:
Project consultants gave presentations on five areas being studied as part of the Draft Environmental Impact Report (DEIR). Note: Each of these presentations can be viewed on the project website, www.greenlineextension.org. Click on Reference Materials, then Current Materials.
Don Cooke and Laura Castelli of Vanasse Hangen Brustlin (VHB) gave an overview on a traffic analysis, including pedestrian and bicycling conditions, conducted at 45 intersections in the project area. It concluded that the Green Line would reduce vehicle trips and generally improve traffic conditions, with the addition of roadway and signalization improvements; however, it also projected the number of intersections in the project area with a “failing” grade would increase from 19 currently to 26 in 2030, with or without the Green Line. Pedestrian improvements would be seen at 33 intersections. The addition of two turning lanes would be recommended on Boston Avenue, at Winthrop Street and at Mystic Valley Parkway, resulting in a loss of about 10 and 16 parking spaces, respectively, on Boston Avenue. Improvements to accommodate at drop-off/pick-up area at Ball Square would result in a loss of 16 parking spaces on Broadway. If a station were to be located at Mystic Valley Parkway, a redesign of the rotary at Mystic Valley Parkway and Alewife Brook Parkway also would be required to bring it up to current standards. Bus service is not expected to be significantly changed; slight route alterations are anticipated for buses serving Lechmere Station (Routes 69, 80, 87 and 88).AIR QUALITYTom Wholley of VHB reported that the Green Line extension would improve air quality on a local and regional basis by reducing levels of carbon monoxide, particulate matter, ozone, and greenhouse gases. He said it was “extremely rare” for a transportation project to show positive impact in all four of these areas. The analysis also showed the greatest air quality benefits would be derived from the alternative that places the terminus station at Mystic Valley Parkway.NOISE AND VIBRATION
Jason Ross of Harris, Miller, Miller and Hanson described the noise and vibration impacts of the relocation of the commuter rail tracks and the addition of the Green Line, and how these impacts can be reduced through measures such as sound barriers, sound insulation, and track treatments. Without mitigation, the relocation of the commuter rail tracks would increase the noise level by 1 to 3 decibels from the existing conditions for locations within 100 feet. The addition of the Green Line would increase the noise level by 1 to 2 decibels from the existing conditions for locations within 50 feet.
Sound barriers would generally reduce the train noise by 7 to 14 decibels. In many cases, future noise levels would be substantially lower than existing noise levels. For example, on Orchard Street, the current average noise level when trains pass by is 71 decibels. With no mitigation, the Green Line project would increase this figure to 74 decibels. Mitigation, in the form of a 10-foot-high sound barrier, would reduce the noise level to 63 decibels, a decrease of 8 decibels from the present conditions. Ross said this is a significant reduction, as a decrease of 10 decibels is equivalent to cutting the noise level in half. The estimated cost of noise barriers was $3.5 million.
Vibration reduction measures include ballast mats under the tracks (estimated cost $3.5 million) and resilient track fasteners ($5.9 million). These are generally effective in reducing vibration by 10 vibration decibels. Also, the commuter rail and Green Line tracks would be built on a concrete slab, known as a “boat section,” which can also reduce vibration.
ENVIRONMENTAL JUSTICE/DISABILITY ACCESS
Ian Harrington of the Central Transportation Planning Staff explained that the principal of Environmental Justice (EJ) is to ensure that the project benefits and does not burden EJ populations, which generally are characterized by lower income levels and higher minority composition. These populations exist in Medford, Somerville and Cambridge.
This presentation only addressed the benefits, not the burden; benefits were rated in terms of improved access to jobs and services (including retail, health care and education), and mobility, congestion and environmental improvements (including reduction in travel time, vehicle miles traveled, and carbon monoxide emissions). Similarly, the project should benefit and not burden the disability populations, which in Medford, Somerville and Cambridge exceed the Eastern Massachusetts average of 17.6 percent of persons over age 5.
The analysis showed that in all cases measured, the addition of Green Line service provided benefits for both the EJ populations and for people with disabilities. Further, in all cases the disability population benefits were greater than those projected to be provided for the non-disability populations; the same was true in most cases for the EJ populations versus the non-EJ populations.
Mark Louro of VHB describe the preliminary plan for roadway and railway work, noting that plans will be formalized in the next phase of the project, the detailed engineering. Roadway work would generally be done during the day with road and lane closures scheduled at off-peak hours. The current estimate shows that 10 road bridges and 3 rail bridges would require reconstruction; 4 new rail structures also would be built.
For the railway work, current rail traffic (commuter, freight) would be maintained. A typical construction sequence would be to excavate the right-of-way where needed and build retaining walls; perform drainage and utility work and pour footings; construct a new outbound track for the commuter rail on the north side of the corridor; shift the current outbound commuter rail track so it becomes the new inbound track; remove the current inbound track; install the two Green Line tracks south of the commuter rail tracks, and construct station platforms, catenary lines, etc.
The next meeting of the Project Advisory Group will take place on Thursday, Jan. 15, 2009, again at St. Clement Parish Hall, 579 Boston Ave., Medford. The time will be determined; given the anticipated large agenda, including a presentation on the terminus station location analysis, the meeting might be scheduled for 3 hours in length, instead of the usual 2 hours.
This meeting will be followed by two public meetings later in January. There will also be a public hearing once the DEIR is filed. The DEIR, which was required to be filed on Dec. 1, 2008, is expected to be filed near the end of January 2009, according to Assistant Project Manager Kate Fichter of EOT.
- Ken Krause, Project Advisory Group member