An 80-year-old, three-span, steel frame bridge on Route 2B in St. Johnsbury, Vermont was in dire need of replacement. One abutment was significantly undermined and the bridge deck and rail were in extremely poor condition. A Super•Cor Buried Bridge with Vist-A-Wall Precast Panel Walls package from Big R Bridge was selected for this project – a first for The Vermont Agency of Transportation (VTrans).
Part of FHA’s CAT II Experimental Technology Program
VTrans had received approval from the Federal Highway Administration’s CAT II Experimental Technology Program to document and test new Buried Bridge and wall systems never used before in Vermont, so they might be added to the approved products list for use on future projects.
Early, multi-partner collaboration was key
The pre-bid design and layout collaboration that took place between the Big R design team, VTrans engineers and their consultant, CLD Engineering, was key to the success of this project. Our project partners were receptive to ideas we were able to bring to the table from past successes. A true design-build approach, it also involved public input around trail and road closures and aesthetics.
Contractor beats Accelerated Bridge Construction (ABC) schedule by five days
Route 2B is a primary roadway in the area and the bridge crosses the popular Lamoille Valley Rail Trail. So the closure time was very compressed, with only a 50-day window from road closure to open-for-traffic. This included demolition and removal of the existing bridge.
Big R Bridge had to move quickly to provide submittals, have the State review them, make changes, and completely produce all materials before the contractor was able to start on site. Vigilant oversight of design, review correspondence and material manufacturing were all key in meeting the installation date.
The contractor, J. P. Sicard, was new to plate construction, so we organized a tour of a similar structure we supplied in Attleboro, MA. We had a rotation of three Big R Representatives on site to provide quick answers should questions arise during the plate assembly and wall construction. Sicard opened Route 2B five days ahead of schedule, earning a bonus for the early completion.
Arch and walls package delivers key benefits
With poor soils on the site, the designer needed a system that could accommodate up to six inches of differential settlement. Our Super•Cor Buried Bridge and Vist-A-Wall Precast Panel Wall package was ideal for these conditions:
- Lighter weight and flexible – able to handle anticipated settlement better than conventional bridges
- Able to use precast footings
- Shorter span required to achieve clearance requirements (47′ instead of 139′)
- Continuous road surface with no bridge deck or joints to maintain
- Buried Bridge and walls were able to accommodate the curved road alignment
AREMA clearance, just in case
The Lamoille Trail is located in an old rail corridor and the new bridge had to be sized to accommodate AREMA clearance requirements, just in case trains were put back into service in the future. The Super•Cor Buried Bridge was able to accommodate that within the geometric limitations of the project.
Big R Bridge Representatives joined Governor Phil Scott, VTrans staff, St. Johnsbury officials, Friends of the Lamoille Valley Rail Trail, and many other project stakeholders and community members to celebrate the grand opening.