As you may know, the “dry bridge” over the railroad near the intersection of Seminary Hill and South Main is slated to be replaced in 2026-27 and will be closed for a year or more. Traffic will be detoured via I-89 and Glen Road, and herein lies the rub.
My concern is that some idiot following their GPS will try to use the Glen Road with a box truck that will not fit through the historic 1848 railroad Arch Bridge. A couple of weeks ago, as I came from West Leb along the Glen Road, there was a medium-sized box truck stopped just west of the underpass. I pulled up alongside and told him not to try to go through. Luckily, he had realized that he couldn’t fit and was turning around. Another person led astray by GPS/Google might not be as smart.
If someone does try to get through and damages the bridge, it is unlikely that it will ever be replaced and would be a great loss to the city and New Hampshire as a whole. In reviewing such problems in terms of covered bridges, I found that there are ways to deal with this issue. Several places have erected “square frames” over the roadway some yards on each side of such a bridge, as stark visual notice of the height ahead. These structures are set at the safe height to go through such a bridge and seem to have solved the problem for at least some of the covered bridges.
I have spoken with folks in the city administration and I know that they share my concern. However, such a mitigation would add to the construction cost and could be cut before the final contract is signed. This letter is to alert residents and railroad history buffs of the potential danger to the Arch Bridge and urge them to contact city officials to ensure that measures are taken to protect the bridge. A barrier on each side of the bridge might be the only real protection.