Only 2 mi. of Interstate 93 south of Manchester, NH, have been directly affected by the rehabilitation of four different bridges along the highway. Once the work is finished, though, traffic flow for miles up and down the highway will be greatly improved.
The Interstate is one of the primary routes north out of Boston, so many travelers headed toward the mountains of New Hampshire and Vermont have to squeeze through the bottleneck there. Traffic must slow once it hits the area just south of the junction with Interstate 293, a road that swings around the west side of Manchester. This construction project will widen that tight spot. Not only will the bridges be rehabilitated, but a sound wall also will be built on the west side of the highway, protecting houses in that area from highway noise.
The bridges spanning Bodwell Road and Cohas Brook were built back in 1962 when the Interstate was first constructed, so they have endured nearly 40 years of heavy traffic. Subsequently, they are in bad need of repair. The southbound bridge over Bodwell Road is 160 ft. long (48.5 m) while the northbound one measures 147 ft. (44.6 m). The one Cohas Brook bridge that is getting the most attention is 151 ft. (45.8 m) long.
Bill Boynton, public information officer for the New Hampshire Department of Transportation (NHDOT) explained that the three bridges are on the “red list” of construction projects, meaning that they demand the most urgent attention. Two of them require new superstructures, including decks, foundations and pile supports, while the other two will be completely rebuilt. All of them also will be widened.
The highway also is being widened although no new lanes will be added for the time being. The changes will let more lanes be added later. Although it is not part of the larger widening project on the interstate between Manchester and Salem, this one dovetails into the other. The work is needed there because the intersection with I-293 creates such a large increase in the volume of traffic.
“The way it was laid out originally, it was adequate,” explained Conrad Skov, contract administrator of NHDOT. “But with the increase of traffic, it became geometrically deficient.” Any construction of new lanes on the highway, making it three or four lanes wide, is still in the planning phase, he added. The road currently has a 24-ft. (7.3 m) travel way with shoulders measuring 4 ft. (1.2 m). When the project is finished, the travel way will be 48 ft. (14.6 m) wide with 12-ft. (3.6 m) shoulders.
Perhaps the most challenging part of the work, though, is the blasting needed to provide more room on the side of the road in case it needs widening. Four separate granite ledge outcrops hanging above the road are being removed. In all, it will affect approximately 130,000 cu. yds. (98,800 cu m) of rock. The rock face stands approximately 40 to 50 ft. (12.1 to 15.2 m) high and 25 ft. (7.6 m) from the highway.
“It’s awkward. They are taking a lot of precautions, so they are taking it down very carefully,” Skov said. What makes it difficult he added, is that granite is such a hard substance. Saunders Drilling and Blasting of Hudson, MA, is in charge of the ledgework. As of mid-March, that part of the project was approximately two-thirds finished.
“It’s amazing what they’re doing with explosives these days. With directional shots, they can very accurately predict where they want it to go,” Skov added. The sound wall that will eventually be built there will accommodate nearby residents, according to Boynton. “But there is no calm way to do that,” he said.
Barletta Heavy Division of Roslindale, MA, is the primary contractor for the $14.2-million project. One of its duties is overseeing traffic control. What makes that unusual is that Barletta is utilizing rolling road blocks that will stop traffic for no more than 10 or 15 minutes at a time. Because access to the site is limited, it is especially important to keep the traffic moving, according to Skov.
“That’s a tall order because they [Barletta] are doing well over 100 blasts,” Skov said.
The Interstate is not the only road in the area getting renovations. Bodwell Road, which travels beneath two of the bridges, is being lowered 4.5 ft. (1.4 m), creating a clearance of 14.5 ft. (4.4 m). It also will be widened to a 24-ft. (7.3 m) travel lane with 4-ft. (1.2 m) shoulders.
One advantage that NHDOT has found during the winter months is that the weather, which has remained unseasonably mild throughout the 2001-2002 year, has not slowed the project at all. The blasting may be the biggest beneficiary of these conditions.
“We’ve had pretty convenient working conditions with very little frost and snow,” Skov said. Such circumstances should help the workers remain on schedule. The project is expected to be finished by July 2002.
A number of other subcontractors also are working on the project, including Brock Industries of Dracut, MA, paving; DeLucca Fencing of Massachusetts, guardrails and fencing; and Continental Paving of Londonderry, NH, coplaning.
Likewise, a wide variety of different machines are being used, dominated primarily by Caterpillars and Komatsus. Barletta has several excavators on hand, including the Caterpillar M318, 330BL and 235D and Komatsu PC400LC. As for dozers and graders, there are Cats, Komatsus and Dressers, as well as three different Komatsu and two Cat loaders and John Deere backhoes. Trucks include four Volvo articulated 35-ton (31.5 t) end dump trucks, a Cat D350E and a Sterling LT9513 boom truck.