Gloucester Drawbridge Replacement 2020 Construction Progress Recap

East Abutment

The existing east abutment was fully demolished. Sixty-six new micro-piles were installed to support the new abutment, which is almost fully constructed. All of the abutment’s concrete slabs have been formed and poured. The majority of the abutment’s concrete wall sections have been constructed and only a few sections of the northeast retaining wall remain to be constructed.

Bascule Span Removal

During fall 2020, a 72-hour channel closure was utilized to perform an early demolition of the existing bridge's moveable bascule span. Before the channel closure, the existing bascule span was locked in place and its counter-weight was removed. The existing timber fender system with timber docking system was also demolished prior to the channel closure. During the closure, the existing bascule span's steel cross-framing was cut and removed. Afterwards, the bascule steel girders were removed. In addition to removing the bascule span over the channel, the contractor demolished the steel west approach span.

Learn more about this type of bridge in our fact sheet

Pier 2

Construction of the southern half of the new Pier 2 has advanced. Pier 2 will hold the trunnion tower (a pier) and machinery for the new moveable bascule span over the channel. The two southern drilled shafts that support the pier have been constructed along with the concrete pier cap and machinery slab platform. The back and front walls of the pier are currently being formed and reinforcing is being installed.

Control Tower

Work has progressed on the construction of the new control tower, which will operate the new bridge. The control tower is located at Pier 3. The drilled shaft, pier cap, and control house have been constructed. The first floor base slab and the exterior concrete walls have also been constructed. Work has also progressed on construction of the interior masonry walls, steel framing and floor slabs, giving us a glimpse of the look of the replacement bridge.

Pier 1

The existing Pier 1 has been fully demolished. This work included removing the existing steel trunnion tower. The trunnion is an axle that supports the bridge span. Once the tower was removed, the pier cap that consisted of timber and steel grillage beams encased in concrete was demolished. The timber and steel piles that supported the pier were either removed or cut below the existing mudline, and the existing timber trestle was also completely removed.

Signals, Power, and Utilities

New submarine cables and submerse conduits have been installed in the channel. These lines will carry power to operate the bridge along with vital MBTA signal systems, including Positive Train Control (PTC). Additional conduits and innerducts have been installed to support future upgrades and improve system resiliency. A new signal gate and Signal Instrument Houses (SIH) have been installed east of the bridge. East of the bridge, the foundation slab that will support the new generator and automatic transfer switch has been constructed.