ARLINGTON- SOMERVILLE- BRIDGE REHABILITATION, A-10-014=S-17-026 (4DI), MYSTIC VALLEY PARKWAY OVER ALEWIFE BROOK

The work to be done under this Contract consists of furnishing all labor, materials and equipment required for the widening of the bridge structure and footings of Bridge No. A-10-014 = S-17-026, Mystic Valley Parkway over Alewife Brook in the Towns of Arlington and Somerville, with a rehabilitated structure providing a 41’-0” travel way, 8’-4” wide shoulders and 10’-0” wide sidewalks on both sides. The proposed work involves character-defining features of the bridge to be replicated. The concrete spandrel walls, concrete coping and end posts, and bridge railings will be replicated in-kind. The exterior appearance of the existing cast stone ring stones will be replicated as part of the construction of the new outer arches. The existing section of Mystic Valley Parkway as it crosses Alewife Brook is 41 feet curb-to-curb with a 5-foot wide sidewalk on the north side and 6’-8” wide sidewalk on the south side. The bridge fascia will be removed from both sides and the bridge will be widened to both the north and south to provide a 41’-0” travel way (curb-to-curb) with a 10’-0” sidewalk on the both sides. The roadway cross-section will consist of two 12’-0” wide travel lanes with 8’-4” outside shoulders. Existing bridge railing will be removed and replaced with a replicated steel railing on the widened structure. New crash-worthy bridge railing will be installed along the curb face on both the north and south side of the bridge. The profile of Mystic Valley Parkway will closely replicate the existing profile. Granite curbing will be provided along both side of the roadway to match existing. Runoff will discharge to an existing closed drainage system through existing catch basins located on both the eastbound and westbound approach to the bridge. A pedestrian cross-walk, with overhead signal, signing and handicap ramps, will be constructed across Mystic Valley Parkway to the west of the bridge. Pavement markings will be placed on the new pavement.