CENTRAL ARTERY / THIRD HARBOR TUNNEL - DESIGN SECTION 4A
Boston, Massachusetts


Our engineering staff provided all civil engineering design services for the Central Artery/Third Harbor Tunnel project, Design Section 4A, which is the entrance to the Ted Williams Tunnel in South Boston, MA. The project ran from D Street on the west to Fid Kennedy Way on the east. Our design and coordination services included all horizontal and vertical alignment, grading, drainage, relocation of utilities, and right-of-way design for this complex tunnel and boat section project.

In addition to the design of the tunnel entrance, we also provided design services for several Massport-owned facilities, including sections of the Temporary Haul Road, the Permanent Haul Road, and the D Street/Ramp Street Extension. One of the larger challenges was working with a 115KV oil-filled pipe-type electrical conduit that supplies electricity to downtown Boston. We coordinated with Nstar (formerly Boston Edison) to construct welded sleeves over the lines where they passed under a relocated railroad line, and we coordinated the relocation of the lines over a 600-foot section where they interfered with construction of the new utility corridor in the Massport Haul Road.

A 36-inch sewer interceptor was relocated to the perimeter of the project area; however it was later discovered that the soft soils in the area would not support the line without the added expense of piles. To deal with this unforeseen situation, we designed a pump station with a force main that was routed through an area with stabile soils.

In addition to the civil engineering design services, our structural engineers designed Ventilation Building #6, which is located at the eastern limit of this project. The structure houses intake and exhaust fans that provide breathable air to the Ted William’s Tunnel.

Client: Massachusetts Turnpike Authority