Image above from the Bike-Walk Alliance of New Hampshire (BWANH)
NHDOT will incorporate a tunnel for the Derry Rail Trail as part of its I-93 Exit 4A interchange project as part of a settlement with the Committee to Save the Derry Rail Trail Tunnel and Rails to Trails Conservancy (RTC), per the conservancy’s February 10 press release.
This is a significant development for one of the most important small-gap closure opportunities in New Hampshire trails. Built on the old Manchester & Lawrence Railroad and now part of the 120-mile Granite State Rail Trail, the Derry Rail Trail goes for about 3.5 miles through Derry, gracefully serving and passing through downtown. It connects to the Londonderry Rail Trail to the north and the Windham Rail Trail to the south. But there is a mile-long gap just north of downtown, and that’s where the Exit 4A project comes in.
In August 2024, the Committee and RTC, represented by WilmerHale, filed a complaint in U.S. District Court to halt Phase 2 of the interchange project. The complaint opposed a “design change, proposed by NHDOT and approved by FHWA in 2024, that removes [the] previously planned tunnel slated to protect the historic right-of-way from a six-lane exit road, replacing it with a steep, at-grade crosswalk and a circuitous, steeply sloped route that abandons the historic railroad corridor.”
In other words: the change replaced an underpass that would be direct, flatter, and respectful of the historic rail right-of-way with an out-of-the-way, at-grade crossing with steep (~5% grade) approaches, pushing trail users to cross 6 lanes of traffic.
The discarding of the tunnel plan shocked trail advocates like the Bike-Walk Alliance of New Hampshire (BWANH) when NHDOT announced it back in October 2021. It wasn’t just how much better the tunnel would be for trail users. The tunnel had been initially proposed and was “reportedly fully funded with Federal money and Toll Credits”, per BWANH. It was also not in a flood zone, whereas the circuitous at-grade crossing would be.
[The tunnel] would allow the safest, most convenient, and most direct route for rail trail users (bicyclists, walkers, joggers, dog walkers, families, children, seniors, and people of all ages using mobility assistance devices, etc) – separated from motor vehicle traffic. This rail trail “tunnel plan” is by far the preferred option, the only one that makes sense, for safety & convenience of rail trail users.
Bike-Walk Alliance of New Hampshire (BWANH, see link above)
Thanks to a favorable court ruling in June 2025 leading to the settlement, the tunnel alternative has won the day!
Originally published: Feb. 26, 2026; edits: Feb. 28
Jeff Brubaker 