The work being done on the Route 1 bridge over the Penobscot River along the coast of Maine is actually a two-part project.
During the summer of 2003, corrosion was discovered on the main cable of the Waldo-Hancock Bridge, a 74-year-old suspension bridge. Its condition forced the contractor, Cianbro Corporation, to do a supplemental cable installation, so half of the bridge’s load was transferred to a new cable.
“It was very challenging. We were on a tight job schedule. It was an emergency job so we had nine weeks,” explained Archie Wheaton, project superintendent of Cianbro. Only one lane of highway was open at a time during the repairs, so half the traffic crossing it was delayed.
But those repairs could only lead to the construction of a replacement bridge adjacent to the old one. Even though the repairs on the old bridge would probably keep it maintained for a long time, only three more years are needed until the new one is finished.
Work has started on that one, a cable-stayed bridge known as the Prospect-Verona Bridge, making it only the second one of that style in all New England. The only other one is the Leonard P. Zakim Bunker Hill Bridge in Boston, recently opened along with the rest of the Big Dig.
Cianbro, of Pittsfield, ME, has joined forces with Reed & Reed to complete the entire project. Cianbro received the 2004 Build America Award from the Associated General Contractors of America (AGC) for its work on the Waldo-Hancock Bridge. It was feted for its engineering work last summer, when 50 percent of the dead load was transferred to the supplemental cables. The work was completed in just three months, well ahead of schedule. Incredibly, with a pace like that, no time was lost for injuries.
“The repairs have never been done in the United States,” Wheaton said. “It’s the first time for repairs of a bridge like that.”
Now that the emergency work has been completed, attention has shifted to the new bridge, which is being built from scratch. The two are side by side right now, but that may be about the only way they can be compared. The new cable-stayed bridge looks somewhat like something designed in the future with all of its cables zeroing in on two points far above the highway. In fact, the footings are 124 ft. (37.6 m) above the deck, so it will be an impressive site when it is finished.
While the old bridge has its two piers in the water, the new one has its two based on solid ground on either side of the Penobscot. The piers could have been constructed in the water as well, but that would have added time to the work. It also demands a permitting process that would have further slowed progress.
Approximately 1,800 ft. (546 m) will sit between the two piers.
Engineers also changed their original plans to use precast concrete for the deck. That was the idea when an extremely fast time schedule was envisioned. But it was decided to pour the concrete right at the job site when they realized that it would be much less expensive than hauling and placing the precast slabs, Wheaton said.
“The new bridge will have a whole different look. The appearance itself will be quite a lot different,” he explained.
For one thing, the new one will be approximately twice as tall as the old one. The Prospect-Verona Bridge will stand in at approximately 400 ft. (121.3 m) above the water, while the Waldo-Hancock is only 230 ft. (69.8 m). But that should not make much difference in the route of the approach, according to Wheaton. The distance from the ground to the bottom of the road deck of the new bridge is 124 ft. (37.6 m), he added.
Just as the repairs done on the first one were impressive, so is the work on its replacement. In fact, just building the footings for the two piers was an ambitious project. Approximately 330 truck loads of concrete were needed to fill an area measuring 70 by 60 ft. (21.2 by 18.2 m) and 16 ft. deep (4.8 m), creating a space of approximately 2,800 cu. yds. (2,128 cu m). Work on the other side required even more concrete, approximately 3,300 cu. yds. (2,508 cu m). That was completed in mid-June.
Officials liken the footings to that of the Washington Monument. About the same amount of concrete is being poured as is found in the monolith in the nation’s capital.
To keep the concrete consistent, the pouring had to be done in a strict time period of 30 straight hours. The work required 58 people and 26 different trucks.
Cianbro and Reed & Reed, the two largest bridge builders in the state, have partnered on this project. While they are both working toward the same goal, they are using different equipment. Cianbro uses Manitowoc cranes (such as the 4100 and the 3900), while Reed & Reed opts for Link-Belt (518 and 218). The plan is to have one company focusing on one side of the river, with the other on the far side, but there is some overlap, according to Wheaton.
The entire project carries a $75-million price tag. State officials feared that the high price might threaten other projects throughout the state. However the Maine Department of Transportation (MDOT) has been permitted to borrow $50 million on the assumption the DOT will receive federal funding. That way the other delays won’t happen.
Construction is expected to be completed by the end of 2006, Wheaton said.