Ongoing restoration of the East Thetford - Lyme Bridge; a year in photos
The bridge is still on track to reopen in October 2024. Stay tuned!
After an initial outcry at the 18-month closure of the antique East Thetford — Lyme bridge for structural repairs, coping without the bridge has become a way of life for residents in both communities.
Thetford residents need not forgo their consumption of pizza from Stella's in Lyme, thanks to the efforts of Gene Kadish and others. Gene organizes a weekly pizza run for those who can get their order to Stella's by 4:00 p.m. Gene and the Thetford Hill Gang pick it up at 6:00 and have it waiting at the Congregational Church by 6:30. It's a wonderful service to the community.
As for the bridge itself, the work zone around it is closed to sightseers for obvious safety reasons. However the NH Department of Transportation (DOT) provides updates on a mostly monthly basis, complete with photos of what's going on.
By July of 2023 work crews had completed the removal of lead paint and the blasting away of rust. Lead paint is a health and environmental hazard, and its removal is no easy matter. There are federal DOT guidelines on how it must be contained while being removed. After the old paint and rust were gone, the primer coat of new paint was applied to the bridge.
By August substantial repairs had been made to the system of vertical and diagonal posts or trusses that connect the upper and lower horizontal members of the bridge. New steel plates and angles were bolted in place to repair rust holes and areas of significant rust pitting.
Above the water line the concrete piers were deteriorating. The weakened concrete was chipped away, then reinforcing steel was added (above) and the piers were encased in new concrete. The photo below shows wooden forms for pouring the concrete.
In September the entire bridge deck was removed.
October 2023 saw the demolition of the backwalls, vertical concrete retaining walls that extend up from the bridge abutments. The backwalls support the bridge expansion joints that allow the deck to naturally expand and contract without cracking. The backwalls also bear the concrete approach slabs and hold back the river embankment that lies under the approach to the bridge.
In November the steel beams or stringers that held up the bridge deck underwent repair or replacement (above), and old-style rivets that held the bridge together were being removed and replaced with bolts.
Structural steel work continued through December.
In January — February 2024 the crew constructed concrete forms in preparation for pouring the concrete bridge deck (above left). Structural steel repairs continued, including replacing the steel lattice work (above right). The bridge abutment on the VT side needed significant repairs, including replacement of steel members and replacement of deteriorated concrete.
In March repairs to the VT abutment continued (above left) while preparations for pouring the concrete bridge deck progressed. The right hand photo above shows some of the steel reinforcing rod that would be incorporated into the concrete deck (below).
In April it was finally warm enough to pour concrete to repair the abutment and backwall on the VT side.
Shear studs were welded to deck beams. Their purpose is to tie the concrete to the steel beams, thus resisting shearing between the two layers and making for a stronger structure.
By May the concrete decks were poured. Expansion joints and curbing along the sides were still to be added. The crew also began to prepare for repairs to the parts of the concrete piers that were below the water line. They started to build a docking system, a necessary step in the installation of a cofferdam. This structure would allow the water around the piers to be pumped away to expose the deteriorated concrete.
By June the new deck was complete. The crew had also completed floats and other preparations for building the cofferdam.
By the start of July the outriggers that will hold the cofferdam in place were installed.
In principle, the steel cofferdam sections will be moved into place so they completely surround each pier. The sections will be secured to the outriggers and the bottom of the cofferdam will rest on the river bed. The dam sections will be attached to each other and made watertight. Then the water will be pumped out, leaving a dry workspace around each pier, in which damaged concrete can be removed and replaced with new reinforced concrete.
A dive team is expected to be on-site this month to begin assembling a multi-section barge for the cofferdam installation.
The bridge is still on track to reopen in October 2024. Stay tuned!
All photos courtesy of NH Department of Transportation