WILLIAMSVILLE — Closure of the Arch Bridge over the Rock River is anticipated to continue through the fall.
As of this week, Renaud Brothers Inc. of Vernon, the contractors for the project, poured the last section of the bridge's south abutment footing.
Next week, pre-cast pieces of the arch for the new bridge will be set.
The bridge on Depot Road, which is being completely reconstructed, has been closed since March 14, and work is expected to be completed in mid-October.
“We've demolished the existing bridge and, over the last few weeks, we've been advancing some of the substructure work, constructing new footings for the abutments,” said Vermont Agency of Transportation Public Information Consultant Hannah Brockhaus.
The construction cost of the bridge is estimated to be $3,439,398, with the state paying 15 percent of the cost, the town paying 5 percent, and the Federal Highway Administration paying 80 percent.
The original Arch Bridge was a historic, reinforced concrete, closed spandrel, elliptical arch built in 1908. The one-lane bridge was 100 feet long and 18 feet wide.
In accordance with Vermont state design standards, the bridge was considered narrow, with shoulder widths of 3.8 feet and a single-lane width of 10 feet. The arch was in poor condition and considered structurally deficient and with a substandard vertical alignment and bridge railing.
The new project will replace the existing arch with one that meets historic requirements.
The Agency of Transportation evaluated alternatives to replace the bridge in a 2015 engineering study that assessed the proposed design criteria for the bridge and roadway alignment, right-of-way impacts, hydraulics, and historic and cultural resources.
Several alternatives were considered, including taking no action, rehabilitating the existing historic arch, fully replacing the bridge with a new reinforced-concrete arch, and fully replacing the bridge with a prefabricated steel beam bridge and concrete arch façade to mimic the original structure.
Given the age of the structure and its structural deficiencies, the engineering study recommended full bridge replacement with an offsite detour.
Senior Structures Project Manager Carolyn Cota has provided details about the work. When it's finished, the new bridge will be a functioning, reinforced concrete arch similar to the original structure with a major axis length of 76.5 feet and a minor axis length of 31 feet to match the original bridge profile.
The new arch will continue to perform as a one-lane bridge via signage and the line-striping pattern on the roadway but will be widened to 28 feet to accommodate any potential future two-lane traffic requirement.
The lines and concrete details of the original spandrel walls will be replicated as closely as possible to the original characteristics. Additionally, all dimensions and proportions of the original arch will be maintained where possible in the new structure.
During construction, the bridge and Depot Road have been and will remain closed, and traffic is being detoured via Grimes Hill Road and Route 30. This detour adds about a half mile to the through route, for an end-to-end distance of 4.5 miles.
Grimes Hill and Dover roads in Williamsville have been reduced to one-lane traffic managed with signals during construction.