Route 72 Manahawkin Bay Bridge Rehab Alleviates Seasonal Traffic Delays
Double Bridges Ensure Safety: The Route 72 Manahawkin Bay Bridges Create Safer Passage to and from Long Beach Island
Long Beach Island that lies in the Atlantic Ocean off of New Jersey is a barrier beach. The island has a significant number of year-round residents and the population swells to nearly 100,000 every summer, as it is a thriving tourist destination. Manahawkin Bay Bridge, the bridge to reach this barrier island, has been reconstructed and is part of a larger construction project.
The Route 72 Manahawkin Bay Bridges Project, which was broken into five separate contracts, was initiated in 2007, after a feasibility assessment phase was completed. From then until 2011, the focus was on securing the approval of the environmental documents, while designing the causeway to meet current standards and ensuring that the structures can withstand the harsh marine environment. The next two years were spent finalizing the design plans and advertising and awarding the first phase of the project to a contractor. Construction began in 2013, and is expected to conclude in 2022. The project itself includes a number of elements such as rehabbing the 60-year-old bridge as well as building a new bridge approximately 10 feet away.
Why a second bridge? "Having two bridges ensures safe egress for the community," says Pankesh Patel, who has served as the Project Manager for the New Jersey Department of Transportation (NJDOT) since the project began. "When future repairs and maintenance needs arise, traffic can be shifted from one structure to another without losing capacity." It also can provide assurance should either bridge be damaged in storms (like the original one which suffered minor damage during Superstorm Sandy), that people will be able to exit the island.
The Route 72 Causeway, originally made use of four bridges with the main bridge 2,400 feet long and three small trestle bridges ranging from 300 to 450 feet long. The old bridge was redesigned and updated, and the superstructure was replaced. In addition, a 6-foot-wide sidewalk and bicycle lane were added to the bridge. People can now walk or bike the 3 miles from Long Beach Island to the mainland or stop at the island – Cedar Bonnet Island – in between. Four recreational areas (and six parking lots) were added so people can go fishing and crabbing. Reconstruction of the older Manahawkin Bridge began in 2016 after the new bridge was completed to ensure that a reliable route to the island remained available at all times.
The portion of Route 72 that leads into the bridge also saw some improvements. Local intersections were redesigned to improve traffic flow, alleviate seasonal traffic delays, and improve drainage.
The Preliminary Design phase was rather lengthy. During this time, an Environmental Assessment was prepared, which had to be approved by a number of agencies including the Federal Highway Administration. While the project avoided environmental impacts to the extent possible, some mitigation was required, including wetland creation, mitigation for freshwater wetlands, and the retrofit of two existing stormwater basins within the Barnegat Bay watershed. Public access improvements were also provided.
The mitigation plan was developed in coordination with regulatory agencies such as the Fish & Wildlife Service, the Department of Environmental Protection (DEP), and the U.S. Army Corps of Engineers. "Due to the many different agencies who partnered with this project, there was a great deal of coordination before construction even began," says Patel.
One particular restriction that came up due to the environmental impacts was significant. Between, January 1 and June 30, work could not take place in the water. This is because the winter flounder spawn during that time, and the fish is protected by the DEP. To avoid halting construction activities during this season, cofferdams were built at the locations of the proposed foundations/piers for the new Manahawkin Bay Bridge. Sheets of corrugated steel were driven into the ground in a rectangular, high enough so that they could also extend above water. After the sheets were installed and made watertight, water was pumped out, and construction was permitted to take place within the cofferdams year–round as a result of dry working conditions created.
Consideration also had to be given to the sea life including fish species and sub aquatic sea life. The permitting agencies required the contractor to provide a bubble curtain (i.e. a ring of forced air in the water around the work area). The bubble curtain was required to minimize noise impacts by reducing sound from transferring through the water and disturbing the fish.
Another wrinkle came due to the presence of the peregrine falcon nest on the existing bridge. "Due to environmental regulations, the contractor could not work within a 200 feet radius of the nest location during mating season," says Patel. "We had to build a separate wooden tower next to the new bridge so the falcon could nest there safely, and avoid impeding construction activities."
A portion of Cedar Bonnet Island (CBI) is part of the Edwin B. Forsythe National Wildlife Refuge. Acquired by the United States Fish and Wildlife Service in the 1990s, the area had never been open for public use. As part of the Refuge’s Comprehensive Conservation Plan, CBI was identified as a priority for wildlife habitat restoration and recreational use. NJDOT worked closely with the USFWS and other stakeholders to create a public Environmental Trail as part of the environmental mitigation included as part of the Route 72 Manahawkin Bay Bridges project. The public access improvements for the project include a 1-mile walking path with pedestrian benches, two gazebo overlooks with picnic tables and interpretive signs located along the path. Ultimately, 45 acres will be used for parkland. Some of this area has been converted into wetlands, which will improve the water going into Barnegat Bay.
"This is a beautiful spot, and we expect it to be popular," says Steve Schapiro, NJDOT Director of Communications. "People can either walk or bike around and enjoy this area which enhances the public experience."
Manahawkin Bay is very shallow – approximately 5 feet deep. The lack of depth makes bringing in barges nearly impossible. Therefore, it was a challenge for the contractor to bring in the necessary heavy equipment, which the project required. "We constructed temporary trestles on the south side of the new bridge so the contractor could bring in heavy equipment and perform the work from the trestles," says Patel.
Two huge cranes were used in the project with one at each end of the bridge. It lifted and then lowered the rebar cages for the foundations 80 to 90 feet below ground level within stabilized drilled excavations. Six 72-inch diameter drilled shafts were used for each proposed footing designed to support the new bridge. The massive diameter is needed to safely transfer all the loads from the bridge to the underlying soils, including effects from storm or seismic events in the bay.
Since the late 1960's, people have identified the bridge via the stinger lighting which adorned the sides. Known as the “String of Pearls,” the lighting feature was meaningful to locals. However, as a result of modern safety requirements, an exact duplicate of the system could not be approved for installation. So, new lighting will replicate what was on the previous bridge with one string of bulbs on the south side of the new bridge and another on the north side of the old bridge. The LED bulbs will be able to be seen from a distance and create an attractive look, similar to the landscape provided by the original lighting.
The $312 million Route 72 Manahawkin Bay Bridges project, which was primarily funded by the federal government, has been a complicated one. However, it has progressed as scheduled for the most part due to the excellent coordination of numerous agencies led by the NJDOT. The project has eased the egress from Long Beach Island and created a park and wetland that is already being appreciated by locals and tourists alike.