Client: Town of North Haven
Construction Cost: $11.1 Million
Project 100-175 involves reconstruction of Sackett Point Road and the replacement of State Bridge No. 03743 in North Haven, Connecticut. The roadway component of this work is approximately 1650 feet, east to west, and includes performing signal work at the intersection with Universal Drive, as well as adding roadway width and turning lanes. There are both overhead and buried utility relocations required, as well as new storm drainage being installed. The bridge replacement is in full, and is designed to occur in 3 phases over the course of 3 construction seasons. The existing two-span bridge is severely corroded and has reached the end of its service life, and will be replaced by a two-span integral abutment bridge founded on piles that is approximately 164’ long and that meets current geometric, load and service standards. There are a series of complexities to this project. The river, on average, has a 6-foot tidal swing and both ebb and floods with the tides each day, providing for very difficult construction and challenging environmental conditions. The site has abutters on each corner of the project, leading to more public information and public relations outreach, as well as staging of construction activities, materials and equipment. The road itself has a relatively high traffic volume (ADT) which resulted in the Town and State determining that closing the road to expedite construction was not feasible, nor was alternating traffic allowed, due to the volume of cars and backups that would result. This constraint led to the bridge being designed to be built in thirds, in 3 stages, resulting in a wider new bridge, while allowing for sidewalks and shoulders. Essentially, a new lane of bridge is built each construction year, working from north to south while replacing the in-service bridge as it progresses. There are buried utilities that are vital to the Town of North Haven under the river, immediately next to the bridge. These include a 20-inch water main and a 30-inch sewer main that flow in a "siphon" under the river. The construction of the new bridge is very close to these facilities, and they are to be closely inspected, monitored and protected throughout construction. The Contractor installed a series of survey prisms attached to sleeve rods that sit on top of the water main, as well as in the soil next to it, to hourly monitor if there are any shifts or settlement. The sewer main was stopped for a period pre-construction and a robot with a high-definition camera run through it, to check for any problems ahead of construction, as well as to record its condition before major activities. Finally, there are seismographs and sub-surface microphones installed in the soil around the bridge to monitor the pile and cofferdam driving activities and to ensure nearby structures are not compromised by this work. The tidal swing, the level of monitoring, and the barge-mounted work on the inner island during Stage 2 of construction are unique. This is also a newer bridge design philosophy, with integral abutments and wingwalls, and encased beam ends. There is also a complicated sequence of cofferdam installation in the river, working around the existing pier, as well as a tremie seal necessary to construction the pier footing, below the water level, in the dry.