This pair of bridges carries Interstate 95 over Tefft Hill Trail in Exeter, RI. The original bridges, constructed in 1966, spanned 57′-6″ over a little-used gravel trail that serves as an access route to the Arcadia Management Area, a managed forest that is also Rhode Island’s largest recreational area. The bridges were built with spans long enough to allow for the future construction of a 30-foot roadway in place of the trail. That roadway construction project never materialized, and the trail has been mostly abandoned in favor of other access routes.
When RIDOT approached BETA to design conventional replacements for these bridges, which had outlived their service lives, BETA proposed instead to replace the bridges with smaller, buried precast concrete arches. With plans for future development of Tefft Hill Trail having been abandoned, the replacement bridges could be significantly smaller than the original bridges, and buried structures would require less maintenance than conventional bridges. RIDOT concurred, and the replacement bridges were designed as 20-foot-span arches.
The project was designed such that the arches, including footings and pedestal walls, were constructed beneath the original superstructures while they remained in service. Compacted backfill was then placed in the annular space between the original abutments and the arches to the extent possible with the original superstructure still in place.
The original superstructure carrying the southbound barrel of I-95 was removed and the arches backfilled in phases to allow for continuous traffic to be maintained on the interstate. The northbound superstructure, however, was removed and the arches backfilled in a single phase. That operation was performed during one weekend closure period of I-95, with traffic detoured to nearby Nooseneck Hill Road.