New $60 Million Bridge in New Jersey to Ease Daily Flow of 145,000 Vehicles
New $60 Million Bridge in New Jersey to Ease Daily Flow of 145,000 VehiclesPutzmeister boom pumps to place 40,000 yards of concrete
Daily traffic using the Edison Bridge over the Raritan River on Route 9 near Perth Amboy, N.J., is currently estimated at 145,000 vehicles. This traffic volume has made the existing bridge functionally obsolete.
Route 9 is a major north-south artery running along the New Jersey shore from Cape May at the state's southern end until it combines with Route 1 to enter New York City. This is the route taken by many New Jersey residents working in New York.
About five years ago, the New Jersey Department of Transportation (NJDOT) began studying ways to eliminate this congestion. It determined the best solution was to construct another bridge between the existing one and the Garden State Parkway Bridge. When completed, this new 4,400-foot (1,341 m) bridge will have two lanes of traffic in each direction. At that point, a $40 million reconstruction project will begin on the existing Edison Bridge.
When rehabilitation on the Edison Bridge is completed, the traffic flow will change again. The new bridge will carry three lanes of southbound traffic, while the rehabilitated Edison Bridge will carry three northbound lanes. This will effectively increase the traffic flow from two lanes to three in each direction.
Bridge is design/build project
The new bridge is a $60 million design/build project awarded to George Harms Construction in Howell, N.J. (A design/build project awards a single contract to a general contractor for both the design and construction of a project.) This project is federally funded under the Transportation Equity Act (TEA-21).
To begin the job, the company first contracted with Frederic R. Harris, Inc., a consulting engineer, to design the bridge. After the plans were approved by NJDOT, the company began construction.
George Harms is using two truck-mounted concrete boom pumps, a Putzmeister 36-Meter and the new 46X-Meter, to place the more than 40,000 cubic yards (30,582 m3) of concrete required. "We had the 36-Meter and bought the 46X because the bridge is more than 110 feet (34 m) tall (over the river) at its highest point," said Tom Hardell, a corporate officer, "and we needed the longer reach." The 46X-Meter has a vertical reach of 149 feet (46 m).
Harms' 46-meter pump is also equipped with a Putzmeister .20H pump cell, the largest in the industry and capable of pumping up to 260 cubic yards (200 m3) of concrete per hour. Most of the concrete used will be a standard DOT mix at 2,500 to 6,500 psi (17 to 44 mpa) with a 4-inch (10 cm) slump.
80 to 100 workers on site
Crews of 80 to 100 workers started on the bridge last December. The first major concrete phase is the construction of 25 piers and two abutments to support the structure. The abutment on the south side of the bridge is 55 feet (17 m) long, 18 feet (6 m) high and 5 feet (1.5 m) wide. It will require 315 cubic yards (241 m3) of concrete. The larger north abutment is 65 feet (20 m) long, 34 feet high (10 m) and 5 feet (1.5 m) wide, requiring 1,050 cubic yards (802 m3) of concrete.
Pier height from pile cap to pier top ranges from 40 to 120 feet (12 to 37 m) high. The amount of concrete per average pier is 920 cubic yards (30 m3), including the footings.
Because 10 of the piers will be in the water, Harms Construction has built temporary trestles over the water to position the boom pumps for the work. For piers located in the middle of the 2,100-foot-wide (640 m) river, barges will be used to take the pumps to the pier sites. Currently they have five footings in place on land and three in the water.
"In the water, the pile are between 40 and 90 feet (12 to 27 m) in length and are seated in rock," said Joe Griffin, another Harms officer. Crews build the cofferdam and excavate the bottom of the structure before driving 24 to 30, 30-inch-diameter (76 cm) steel piles in each. Five to 15 feet (1.5 to 4.6 m) of Tremie concrete is then poured. This 2,000 psi (14 mpa) concrete cures in the water.
Tremie seal keeps water out
"We pump this concrete before dewatering the cofferdam to create a water-tight seal in the bottom of the structure," said Jim Duffe, Harms' project manager. "If we pumped out the water before sealing the bottom of the cofferdam, water would seep in under it and fill it up again.
" When the Tremie seal cures, the water is removed, and the piles are cut off, cleaned out and filled with 15 to 20 feet (4.6 to 6 m) of concrete. Then the reinforcing bars are placed and the footings are poured. Between 245 and 470 cubic yards (187 and 359 m3) of concrete are needed for each footing. Eventually the cofferdam sheeting is cut off at the top of the footing and under the water level, placing the footing under water. These footings will support the 10 piers in the water.
"Once we start the major concrete work for the bridge deck in the fall, we'll be placing about 1,000 yards (765 m3) of concrete a day," said Griffin. For this work they will use high-performance, 4,000 psi (28 mpa) concrete.
The bridge deck will consist of nine spans, or 1,800 feet (549 m), of structural steel. The concrete columns rising up to support these spans will be cast in place. The approach spans of the bridge will consist of pre-stressed concrete, made integral with the substructure by means of a post-tensioned cap.
"Everything's on schedule"
Dave Lambert, NJDOT project manager, called the new bridge project one of the smoothest of the large projects the department has going. "Everything's on schedule, if not even a little ahead," he said, "which is unusual for a project this size." Lambert said the bridge is the tallest under construction in New Jersey at this time.
The new bridge should be completed in June 2002. The rehabilitation work on the old Edison Bridge is expected to be completed by the end of 2004.