To improve traffic flow between Perth Amboy and Sayreville, NJ, in an area with one of the highest concentrations of over-water crossings in the country, George Harms Construction Co. Inc. is building the state’s first precast, post-tensioned segmental concrete highway bridges.
Under a $109-million contract with the New Jersey Department of Transportation (NJDOT), Harms, of Howell, NJ, is replacing the existing Route 35 Victory Bridge and approaches over the Raritan River with two virtually identical spans, each having two 12-ft.-wide (3.6 m) traffic lanes, shoulders and sidewalks, plus new approaches.
The existing bridge, originally built in 1926, has what is said to be the oldest swing span in New Jersey. It lies almost at water level and has four narrow lanes, with no shoulders. Although there are two other routes across the Raritan at this point, the Route 35 Victory Bridge still has a hefty traffic count. And just about any passing vessel, except a small runabout, requires opening the bridge, stopping traffic.
When complete, the new Victory Bridge will be 1.3 mi. (2.1 km) long, with twin 4,000-ft.-long (1,200 m) spans high enough to accommodate marine traffic, running from Fayette Street in Perth Amboy to the Route 35 Victory Plaza Circle in Sayreville. The circle, which joins Route 35, Route 9 and two local roads, is being rebuilt as a grade-separated interchange under a different contract. During construction of the second span, Harms will demolish the existing bridge as Route 35 traffic is routed over the first span.
The reconstructed Victory Bridge (actually bridges) will join new spans of the Route 9 bridge and the Alfred E. Driscoll Bridge of the Garden State Parkway, all crossing from Woodbridge-Perth Amboy to Sayreville, across the Raritan River. Harms completed a new span of the Route 9 Edison bridge in 2001, seven months ahead of schedule.
Schiavone Construction Co., Secaucus, NJ, is currently finishing up rebuilding the other span, the original. The Driscoll bridge also is being augmented with the addition of a third span being erected alongside the existing ones by PKF-Mark III, Newtown, PA. When this span is in operation, the Garden State Parkway will have seven full lanes over water in each direction, matching the land configuration. In all, there will be seven spans with a total of 24 lanes.
That may finally relieve the legendary traffic backups to and from the Jersey Shore that occur during summer weekends.
Harms brings a string of successful completions for NJDOT to the current job. In addition to the Route 9 bridge, the firm built the Route 1/Route 130 interchange in North Brunswick, bridgework for the Route 21 airport interchange in Newark and the Hightstown Bypass.
Work on the Route 35 bridge began in December 2002 and is scheduled for completion in December 2005. As Edward Nyland, president of Harms, noted, “This is an aggressive completion date.” However, he said Harms is pretty much on schedule. In November 2003, work was beginning on the critical over-the-water section.
The current timeline on the project is a bit deceptive. The first three months of the project were marked by severe winter weather, followed by unusually heavy rains in the spring and summer. Also, since this is Harms’ and NJDOT’s first precast, post-tensioned segmental concrete project, the first span may take longer than the next, as Nyland pointed out, because Harms will be able to work more efficiently the second time around.
Plus, the technology for post-tensioned box girder sections has been around for a while; it was developed in Europe around 30 to 40 years ago and has been used on numerous projects in the United States.
Basically the bridge consists of hollow trapezoidal-shaped concrete sections, approximately 9 ft. (2.7 m) long, 30 ft. (9.1 m) wide at the top and 12 ft. (3.6 m) deep, supported atop piers, and with post-tensioning holes cast in the sections. They are in effect strung together like beads, except that they are linked by post-tensioning cables. In addition to being cemented by epoxy at the joints, they are held together at the top by compression and at the bottom by tension.
Proponents of segmental bridges cite several advantages:
1. Low maintenance.
2. Minimal paving. The traffic surface is the top of each section.
3. Better quality control, because concrete is cast in a factory, rather than poured in place.
Over land, the sections are built from one pier to the next, typically spanning 150 ft. (45 m), by being stacked in place using a specially designed beam carrier. A crane lifts the precast sections and spots them on a twin-beam carrier, which attaches to the piers by friction clamps. The carrier, moving on rollers and rails, positions each section so it can be precisely aligned with jacks. The carrier, built by Deal s.r.l., Udine, Italy, is designed for segmental bridge construction and built to the specifications of the Harms job.
On the over-water spans of 940 ft. (290 m) and 300 ft. (92 m), Harms uses a balanced cantilever method, building sections out from each side of a pier one at a time, simultaneously, so they are in balance. These are built out to join to the connecting spans on either side. Temporary steel cables hold the sections in place until the post-tensioning strands can be permanently set.
The piers themselves consist of precast sections stacked one on top of another and post-tensioned together. The job calls for 58,000-plus cu. yd. (44,000 cu m) of concrete, of which 38,000 cu. yd. (29,000 cu m) is in the precast structures. There will be 2.56 million lbs. (1.15 million kg) of post-tensioning steel installed.
The precast 6,000 and 8,000 psi (420 and 560 kg/sq cm) compressive strength sections come by barge direct to the job site from Bayshore Concrete Products Corp., Cape Charles, VA. Bayshore also supplied precast sections for the recently completed AirTrain light rail system from JFK airport to two mass transit stations in Queens. However, these were barged to Camden, NJ, and trucked to the job site.
As Andy McConnell of Harms pointed out, the hollow precast sections form a tunnel, so utilities such as fire pipes and wiring can be strung through them, as well as the post-tensioning cables and their sheaths. The tunnel protects the utilities and cables from the weather so they can be more easily maintained.
With precast construction, the key pieces of equipment are Harms’ Manitowoc crawler cranes, which include models 777, 888, 2250 and two 4100s in the ringer configuration. These work from the top of the bridge, on land under the bridge and from barges in the water.
Overseeing the segmental construction portion are companies of the Figg Engineering Group, Tallahassee, FL. Figg, acknowledged as the originators of and experts on segmental construction in this country, are performing design, consulting and inspection services together.
While the bridge surface is part of the precast sections, the sidewalks and side barriers are poured in place concrete with reinforcing steel. A Gomaco slipform curb machine is used for the barriers.
For the foundations on land, Harms is driving more than 78,000 linear ft . (23,800 m) of 16 in. and 24 in. (40.6 to 61 cm) steel pipe piles. On water Harms is drilling 6,300 linear ft (1,920 m) of 5.5 ft. to 8 ft (1.6 to 2.4 m) diameter shafts. All drilled shafts are sunk into sockets of 16 ft. to 24 ft (4.8 to 7.2 m) of bedrock. To do this, Harms uses a Bauer pile top drill rig with a recirculating cutting fluid system and a unit to screen cuttings.
With this method dewatering is not necessary — all operations in sinking the shafts are performed totally in the water, up until concrete is poured. Then the concrete displaces the water inside the steel casings.
Nyland noted that while there isn’t much of it to drill through, about 900 ft. (300 m), the rock is probably the most difficult he’s ever encountered — “its compressive strength is 45,000 to 50,000 psi.” By contrast, the standard compressive strength of cured concrete is only 1/10th of that. However, by changing drill heads, Harms continues to use the Bauer rig even in the hardest rock.
The job includes 73,800 cu. yds. (56,000 cu m) of excavation, for the new approaches on either end of the bridge (including 68,000 tons [61,200 t] of material that has to be trucked off site), and 14,600 tons (13,100 t) of base, intermediate and surface paving courses of hotmix asphalt, again for the approaches.
Besides the cranes, the workhorses on the Harms jobs are Cat excavators and wheel loaders, equipped with numerous specialized attachments in addition to buckets.
When complete, the new Victory Bridge will provide a safer crossing for vehicles without the interruptions of boat and ship traffic. It also will join several new spans on one of the most impressive displays of bridge building in the Northeast.