By: Big R Bridge
The nominated project was a replacement for a 139’ long 3-span bridge constructed in 1936. The project was designed by Big R Bridge through collaboration with the Vermont Agency of Transportation (VTRANS) and CLD Engineers (project engineer). This project is the first deep corrugated structural plate Buried Bridge project in Vermont.
The bridge carries Vermont state route 2B over a recreation trail. The trail was recently converted from an old rail line. The public was hesitant to give up the use of the trail for construction and VTRANS had to ensure accelerated bridge construction (ABC) methods were used to limit closure of the trail and road crossing above in order to obtain public
support for the project. The project required that the new bridge provide a standard single track AREMA clearance to accommodate the possibility that the trail could be put into use for train traffic in the future. There were also limitations on the structure height, as the road could not be raised. Big R Bridge was able to provide a custom high profile arch geometry to meet both requirements.
VTRANS negotiated a 50 day closure to complete the project. This included demolition of the existing bridge, excavation, foundation construction, structure assembly, structure backfill & construction of precast panel MSE headwalls, and paving & construction of guard rails.
Because a flexible Buried Bridge was selected for the bridge replacement, the geotechnical engineer was able to provide higher foundation bearing pressures than could be used for a rigid (precast concrete) structure to allow settlement of the structure to match the anticipated settlement of the approach embankments (about 2.5 inches). This allowed for the use of precast concrete footings, which accelerated construction of the foundation by about 1 week. The contractor completed assembly of the 86 plate structure in about 1.5 days and was immediately able to start setting the precast panels for the MSE headwalls and start backfilling. Through careful coordination of the design with VTRANS and CLD Engineering and using a deep corrugated Buried Bridge structure with precast concrete foundations, the contractor was able to complete construction 5 days ahead of schedule.
For more details visit the VTRANS site here. 