Sagamore Creek Bridge


Sagamore Creek Bridge

Portsmouth, NH

About this Project

The City of Portsmouth selected FST to design the scheduled replacement of the 72-year-old Sagamore Creek Bridge. The previous 400-foot-long bridge spanned a tidal, navigable channel, and was a 3-span continuous steel girder structure. The harsh saltwater environment and road salt carryover caused severe deterioration of the floor beams and other components of the bridge.

To ensure that the bridge was able to continue serving the community until it was replaced, the City hired FST to perform an interim inspection and repairs program. FST’s work began with a detailed under-bridge access inspection to verify the extent of deterioration on the floor beams and other components, and continued with preparation of contract drawings for the installation of 14 supplemental floor beams and other repairs. The heavily deteriorated floorbeam flanges and other components were locally cleaned, photographed, and measured to estimate the amount of remaining effective steel.

FST performed resident engineering services for the interim repairs that were completed in 2010. The bridge was then posted at a 6-ton load limit pending replacement. FST’s work continued with final design and NEPA documentation for the bridge removal and replacement with a similarly configured bridge, in accordance with its historical nature.

On December 23, 2014, the new Sagamore Bridge opened to traffic. The new bridge is wider, allowing for easier vehicular, pedestrian and bicycle use traveling between Portsmouth and points in Rye and New Castle.

On the eve of the new bridge's opening, Public Works Director Peter Rice told the Portsmouth Herald: "We look forward to having this critical bridge reopen again. It's wider, has a bike lane on both sides and a wide sidewalk. It's a beautiful bridge."

The old bridge was known as "Singing Bridge" because of the sound made when cars drove over the bridge's grate floor. The new bridge has no grates so "it won't sing anymore," said Rice.

More Information

Owner: City of Portsmouth

Location: Portsmouth, New Hampshire

Highlights: FST created a wider, more multi-faceted bridge that accommodates pedestrians and bicyclists as well as vehicular traffic.Public Works Director Peter Rice called it "a beautiful bridge." Expected to be shut down until the spring of 2015, the bridge opened before Christmas 2014.