Project Summary

Hoyle Tanner provided design and permitting services to NHDOT for the replacement of the existing US Route 2 bridge over the Connecticut River which spans between Lancaster, New Hampshire and Guildhall, Vermont. Services included evaluation of rehabilitation and replacement alternatives to address the deficiencies of the existing structure. The previous bridge was 398′ long two-span High Parker Steel Through Truss constructed in 1950. Each span was 198′ long, supported by concrete abutments and a river pier. Over the years, environmental deterioration and vehicular impact led to damage to the structure. As the bridge had a high percentage of truck traffic crossing it, the limited vertical clearance of 14′-9″ caused logging trucks to impact the portal bracing, causing damage not only to the bracing, but to adjacent truss members also.  

Alternatives were evaluated through a comprehensive NEPA process; they included rehabilitation, replacement on a new alignment, and replacement on the existing alignment. Traffic control was also an important consideration, as the detour length could create issues with emergency response, local businesses and school bus traffic. Environmental investigations included an archaeological Phase IA and Phase IB, a mussel biological assessment, and an Individual Inventory Form to determine the historic integrity and eligibility of the bridge structure itself. The existing bridge was replaced with a new 400′ long two-span steel girder structure located upstream of the existing structure, allowing the previous bridge to maintain traffic during the construction of the new structure. The river pier is supported on drilled shafts.