Work to rebuild two I-89 bridges over the Connecticut River in Lebanon, N.H., is under way in a job that will involve constructing one new bridge to replace the two existing bridges.
Work to rebuild two I-89 bridges over the Connecticut River in Lebanon, N.H., is under way in a job that will involve constructing one new bridge to replace the two existing bridges.
R.S. Audley of Bow, N.H., is the contractor on the $43.8 million job that began in late August and will be completed in September 2025.
The 840-ft. "sister bridges" were constructed in 1966 and carry approximately 41,000 vehicles a day and are showing "severe signs of distress," according to a 2017 grant application from the New Hampshire Department of Transportation. The bridges "exhibit signs of cracking, delamination and efflorescent," according to a separate 2014 report, "and the lead-based paint system is evidenced by cracking, flaking and peeling with light rust formed in many locations."
The bridges are Number 2 and 3 on New Hampshire DOT's "red list," meaning they are in poor condition.
The current project will construct a new bridge between the existing bridges.
"This project is phased construction," said Eileen Meaney, spokesperson of NHDOT. "We will construct a new bridge between the existing two bridges and then move the southbound traffic onto the new middle bridge. While the southbound traffic is on the middle bridge we will reconstruct the upper portion of the old southbound bridge. When that phase is complete we will move the southbound traffic to the old location and move the northbound traffic to the middle bridge. In order to complete construction of a new bridge between the two existing bridges, we need to construct a new foundation and pier for each of the five piers and two abutments. This will include a work trestle that spans across the entire river, which is a temporary structure that allows cranes and heavy equipment access to the individual pier locations."
Scott Stevens, vice president and bridge engineer of R.S. Audley, said, "The new bridge is in the middle of a superstructure. We will take the southbound bridge and flop it onto the new bridge, then take the deck and guardrail down and rebuild the pier caps and abutments and connect the new bridge with the middle bridge. There are two bridges with a gap in between and new piers and abutments. We will free up the middle bridges one at a time and take the superstructure down and have one superstructure at the end. Now, there is a northbound and southbound bridge with a gap in between. We'll build piers and abutments in the gap and take the steel and bridge deck down on both the northbound and southbound bridges and install the new bridge."
Work on the job has just begun and Stevens said, "All we have done so far is build an access road into the future trestle location."
He said the trestle will go from one bank of the Connecticut River to the other to provide access to the bridges. It will be made with steel pilings and contain wooden timber crane mats.
The new bridge will be 840-ft. long and 110-ft. wide, which is two acres of bridge, according to Stevens.
Stevens called this "a complicated job" that will require 3.5 million lbs. of structural steel, 500,000 lbs. of uncoated reinforcing steel and 600,000 lbs. of epoxy coated reinforcing steel. The job will utilize 5,000 cu. yds. of concrete, which makes it "a significant bridge project for New Hampshire."
The construction equipment used on the job includes Link-Belt 238, 218 and 1400 cranes, a Manitowoc 10,000 crane, a Caterpillar 745 truck and Caterpillar 349 and 345 excavators, he said.
"When all is said and done, these three bridges will be joined as one with deck closure replacements to make one super wide structure," Stevens said. "We are extremely fortunate to have a project of this magnitude and scale right now. Especially, because it is in our home state of New Hampshire."
R.S. Audley won the job with a low bid and the $43.8 million contract will be paid by state and federal monies that include a U.S. Department of Transportation Tiger Grant, Meaney said. CEG
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