2026 ACEC-NH & NHDOT Technical Exchange Conference

Session 14A: ABC UHPC Overlay Bridge Replacement, Rockingham, VT 
Speaker: Adam Stockin & Tim Polson, WSP
-This Accelerated Bridge Construction (ABC) project consisted of the replacement of a 59’ steel beam bridge perched on deep ledge cuts over the Green Mountain Railroad carrying Route 5 built in 1929. To minimize impacts to the traveling public and the railroad, the bridge was replaced in 28 days.  The proposed bridge consisted of cast in place subfootings with dowels into existing ledge and prefabricated substructure and superstructure units.
While UHPC overlays are typically utilized for deck rehabilitation projects, VTrans received an increase in the federal share to utilize this innovative technology for this replacement project. One of the project goals was to serve as a pilot project for VTrans to better understand specifying and constructing UHPC overlays to add this tool to the toolbox for future bridge rehabilitations. The specification was created for this project and included a mockup pour at the specified 7% profile grade prior to the overlay deck placement. Since this was the first placement of its kind in the region, this mockup built confidence for the owner and contractor for the ultimate placement. As another avenue to learn more about the material, VTrans required that the overlay be placed one half at a time to resemble the typical phased construction placement.
The project was successful in meeting the current needs of the community while providing future value for the use of this innovative technology which greatly increases the service life of bridges.

Session 14B: Delivering a Multi-phased Bridge Rehabilitation for the I-89 Connecticut River Crossing that Improves Roadway Capacity
Speakers: TBD
-Located between Exit 20 in New Hampshire and the I 89/I 91 interchange in Vermont, the bridges carrying I-89 over the Connecticut River have received limited repairs since their construction in the 1960s. Their Red List designation based on their deteriorated superstructures, growing traffic demands, and constrained work zone created a complex challenge requiring a coordinated, multi year effort across both states and several disciplines. This presentation will show how the design team addressed these challenges to correct structural deficiencies and improve roadway capacity, and how the construction team is implementing the design.