Table Station Elements

Transcription

1 The overall layout of the station in the Preferred Alternative (Modified Alternative 2) is described in Table Table Station Elements Ground Level Mezzanine Level Platform Level Existing/Upgraded Elements Two stairway entrances (one on the north side and one on the south side). One communications/signals room. One unpaid lobby with two sets of stairs (north and south sides). Two AFC arrays (north/outbound and south/inbound sides) to enter paid lobby. 250 foot long, seven foot wide outbound platform. 250 foot long, seven foot wide inbound platform. Two sets of stairs (one on each platform). Two canopies (one on each platform). New Elements Two unpaid elevator lobbies (one on the north side and one on the south side). Two paid elevator lobbies (north and south sides) with AFC at each. Two elevator equipment rooms (north and south sides). Emergency generator. Transformer pad. One electrical room. AFC/signal room. Elevator access to both platforms from paid area. Mini-high ramp with canopy located at the west end of outbound platform. Mini-high ramp located at the east end of inbound platform. One south elevator connecting bridge. Access between the ground and the mezzanine levels via stairs will continue, with patrons paying to enter the paid lobby on the mezzanine level before continuing up the stairs to the platform level. Conversely, passengers alighting at the platform level can proceed directly to the mezzanine level via the stairs and then continue down either the north or south stairway from the mezzanine level to ground level. Figures and present the ground level and mezzanine layouts for the Preferred Alternative (Modified Alternative 2). An emergency track crossing between the two platforms is proposed to assist passengers with disabilities in the event that one of the two elevators is out of service. For example, if the elevator to the desired platform is not operational, passengers requiring elevator access can reach that platform by taking the operating elevator to the opposite platform. Then, with the assistance of an MBTA official, it will be possible to cross the track to the opposite platform and board the trolley going in the desired direction. This design would provide for a sliding, lockable gate system between the tracks and modifications to the track to permit easy passage of a wheelchair. Massachusetts Bay Transportation Authority 13

2 Figure Preferred Alternative Modified Alternative 2 Ground Level

3 Figure Preferred Alternative Modified Alternative 2 Mezzanine Level

4 As part of ADA compliance, the physical aspects of the accessible route from grade to train include: New ground level lobby with fare vending machine and accessible gate (ADA and tall); New elevators for access to the inbound and outbound platforms. Elevator doors are located close to the AFC once passengers are through the gate; Entry to elevator cab through a 3.5 foot wide door and exit through a similar door across from the first one (front/back system); Arrival on station platforms raised eight inches above top of rail (ATR), with updated lighting, signage, and public address system; Widened platforms on the viaduct portions of the station for entry into a low floor vehicle (Type 8) through a bridge plate extending from the vehicle, at any platform location; Raised platform (currently the platform is too low from the vehicle s floor for the bridge plate to work properly); Entry into a Type 7 car through a covered mini-high ramp and drop-down bridge plate from the top landing into the front door opening of the vehicle. This activity requires a two stop procedure, one stop for the general public and a second stop (further downstream) for passengers at the mini-high ramp. The mini-high ramp areas will be designed to provide a level of protection from the elements equal to the part of the station for the general public; and Areas of refuge on the platforms equipped with call boxes, signage, and a finish material distinction located in the elevator waiting areas and out of the way of the general passenger flow, as well as on the top landing of the existing stairs. Areas of refuge on the mezzanine level are located adjacent to each station entrance in the unpaid lobby. As part of compliance with the State Building Code, the following are recommended: Each of the existing stairs provides the main means of egress during an emergency at the platform level. A second means of egress exists a few feet away from the west end of both platforms through viaduct Pier 3. Access to Pier 3 from both inbound and outbound platforms is provided via the safety walks on the viaduct (see Figure 7.5-4). With some structural modifications in the interior of Pier 3, emergency stairs connecting the platform to the grade level will be located inside the pier enclosure. These stairs discharge to an open area under the viaduct adjacent to the sidewalk, which constitutes an area of safety according to the egress code in effect. 3 The following are other recommended improvements in the station that are not required by any code or regulation: Installation of an emergency track crossing for elevator redundancy with associated curb cuts at the west end of the platforms; Replacement of delaminating wall surfaces along the back of platform with a new metal panel system providing increased openings and, thus, significantly more visibility from outside the station; Relocation of billboard on south side of station to accommodate elevator; Closure of gaps/voids between tracks at the platform level that pose a virtual risk to passengers; Replacement of the deteriorating chain link fence along the viaduct balustrade with a simple picket fence matching the historical context and era of the viaduct; Replacement of the station gates at the mezzanine with glazed double doors offering weather protection for patrons inside the mezzanine; Possibility of offering weather protection in stairwells with the installation of new glass panels as part of an add-alternate construction bid; and Directional signage updates throughout the station, as well as in the station vicinity, to popular destinations for passengers. 3 NFPA 130. Massachusetts Bay Transportation Authority 16

5 After the Preferred Alternative (Modified Alternative 2) was selected, further coordination with the Boston Landmarks Commission (BLC) and Cambridge Historic Commission (CHC) was undertaken to specifically address avoidance measures in relation to cultural resources. Elevators The design of the station elevators was developed in response to BLC and CHC comments regarding color, materials, and relation to the area s historic context. The BLC also requested that the MBTA consider an alternative type of elevator that is shorter than the machine-roomless (MRL) type. The feasibility of a hydraulic elevator was investigated but was found to have several drawbacks compared to the MRL, including: increased power consumption; increased risk of ground contamination; 30 to 50 percent more space needed for machine room; and increased maintenance requirements. Due to these considerations, the BLC determined that the MRL is a better suited alternative for this project. Relocating the south elevator in towards the tracks to diminish its profile along the face of the viaduct was also investigated. Construction would be difficult due to the presence of main columns supporting the station and viaduct. Other drawbacks included loss of circulation space in the mezzanine; difficulty in construction phasing and maintaining an operable station during construction; and difficulty in accommodating a possible future pedestrian bridge. Relocation of the elevator towards the tracks was dropped from further consideration, largely because of the presence of the main columns. Lechmere Viaduct Due to existing conditions and clearance standards for the Green Line trains, it is not possible to realign the Green Line tracks to avoid widening the viaduct and relocating/replacing the parapet wall. The width of the platform must to be approximately six feet, nine inches and all upgrades must provide for three-car train sets. Shadow studies were conducted for the two alternatives for the parapet, deep shelf and sloped shelf. The BLC and CHC agreed that the benefits in regards to shadow with a sloped shelf do not outweigh the loss of clarity in the banding across the viaduct spans. The sloped shelf is also more difficult to construct. Mini-High Platform Canopy Design of the mini-high canopy was developed with input from the BLC and CHC on style, size, and materials. The existing structure of the station is composed of unprotected steel members (columns, beams, girders, braces, etc.). One of the design objectives is to allow the station structure to remain as unprotected from fire hazards as is feasible while complying with applicable codes and regulations. This objective aims to eliminate the scenario that would require structural fireproofing (a significant cost implication to the project). Additionally, in order to maintain a Type II construction classification, certain station parts that are made of combustible materials, such as the wooden planks on the existing canopies and the plywood panels found on the west boundary of the mezzanine, need to be replaced. Massachusetts Bay Transportation Authority 17 CLICK HERE FOR NEXT PAGE