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At the time of construction, the rehabilitation of Route 18 was New Jersey DOT's largest project to date. At its peak, 200 crewmembers worked around the clock at 15 stations across the state. Photo: The Conti Group

By Victoria K. Sicaras

ROUTE 18 RECONSTRUCTION

CLIENT:8New Jersey DOT (NJDOT)
AEC FIRM:8The Conti Group
COST: $215 million; more than 95% federally funded, the rest by NJDOT and the City of New Brunswick
PROJECT DELIVERY METHOD: Design-bid-build
COMPLETED: April 2010

We chose this project not just for its innovative engineering, but also for the extent to which it involved the public and other governmental agencies in decision-making. DOT managers began partnering with stakeholders six years before a shovel hit the ground in August 2005, using context-sensitive design to balance their need to move traffic swiftly and safely with their constituents' desire for access to beautiful public spaces.

They used the challenge before them — eliminating one of New Jersey's worst bottlenecks — to open a 2-mile stretch of arterial road to pedestrians and bicyclists as well as 85,000 motorists trying to get downtown. Eight bridges — four for vehicles and four for pedestrians — would be demolished, built, and/or rehabilitated; a four-lane highway would expand to eight lanes; and an intelligent transportation system would be installed to facilitate traffic flow.

Elevating the outer roadways to separate local traffic from express lanes improved flows but also necessitated building 25 retaining walls. That required 14 major traffic shifts over five years, producing the first example of successful partnering: DOT managers had to accommodate Rutgers University's bus route, ambulances coming to and from three hospitals, and employees of the world headquarters of Johnson & Johnson Services Inc.

Here's where preparation paid off.

In 1999, DOT managers had assembled a Community Partnering Team with nearly 70 members and invited guests representing New Brunswick and other affected towns and counties; the state's department of environmental protection and the Federal Highway Administration; and neighborhoods, businesses, hospitals, and associations.

In addition to molding the construction schedule for minimum traffic disruption, the team hammered out details — like how to improve pedestrian intersections and where to add traffic signals and lighting — that would enable residents to safely access recreational and waterfront resources via paths along the elevated roads. A ramped promenade from a new bridge provides a gorgeous view of the Raritan River as well as an entranceway into the city and a park that now has a new amphitheater.

Another impressive aspect of the project — a 593-foot-long, 61-foot-high precast concrete barrel arch structure that also connects to the park — is the largest bridge of its kind in North America. It has eight arch barrels, each with a span of 66 feet and a rise of 20 feet. A total of 16 precast pieces were used per barrel. The concrete spandrel panels were cast with formliners that replicate the cut-stone masonry finish of other bridges in the area.

Edison, N.J.-based AEC firm The Conti Group developed a new way to install the precast units.

Each arch consisted of two 33-ton half arches, a “male” and “female” section that formed each barrel. Temporary hydraulic structures braced the first arch segments until the forces were balanced out enough that the bracing could be removed. Using this method, all bays were set in less than three weeks — an accelerated time span that helped compress the construction schedule and reduce overall costs.

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