"August 31st was our first day to start mining," Ed Pietrasz, resident engineer and construction manager for Parsons Corporation, told the Union Leader in September. Since then, a 281-ton tunnel boring machine called Granite Janet has been cutting through the ground beneath Manchester around the clock. In soft earth it moves about five feet at a time.
Nobody walking along the river can see the machine. Paths close where the tunnel comes up to the surface, at its launch site, its drop shafts and its exit. Two of those spots have shut sections of trail, and the City expects both to stay closed until fall 2028. Through the rest of 2026 and into the next two seasons, your best routes are the ones that stay clear of that line.
A Tunnel You Only Meet at Its Ends
The Union Leader reports that the tunnel begins just south of the Queen City Bridge, on the east side of the Merrimack River. From there it runs about 2½ miles northeast and comes out on Mammoth Road at a former CVS, across the street from the new CVS at 271 Mammoth Road. The tunnel will be 12½ feet in diameter and sit 30 to 80 feet underground. The paper puts construction at 2025 through 2028.
The launch site is the part of the project you can actually see. Granite Janet arrived in June on an oversized truck and was parked in a lot next to the Queen City Bridge. Bay Crane Companies then used a 450-ton crane and a 700-ton crane to lower the pieces into the launch pit, where the machine was assembled. From the Queen City Avenue Bridge you can see the tanks that hold the project's slurry. The City's CBDT work progress page says crews are still installing support gantries and delivering precast concrete tunnel segments to the machine.
The City describes the tunnel as part of its effort to cut the combined sewer overflows that reach the Merrimack River after heavy rain. The two cost figures in circulation don't match. The City's project page says the investment is over $360 million, and the Union Leader's September story says $428 million.
Two Hillside Middle School seventh graders picked the name through a Manchester School District naming project. It honors engineer Janet Bonnema.
The Two Closures That Outlast This Season
The first trail closure is already more than a year old. On September 8, 2025, the City closed the Riverwalk between Dunbar Street and Riverwalk Way for the tunnel project. It expects the section to reopen in fall 2028.
The second closure is new this fall, at the tunnel's other end. The work-progress page lists Drop Shaft 7 "On Mammoth Rd. at Rockingham Trail," with utility relocation for site access underway. The City posted an extended closure notice for the Rockingham Recreational Trail on September 25, 2026, also with a fall 2028 reopening. The notice says:
- The trail can still be reached from Oakland Ave. and Woodbine Ave.
- The crosswalk at the Mammoth Road trailhead is closed.
- Signs on site mark the closure limits for pedestrians and cyclists.
The posted notice is missing two details. Its start-date field still reads "September X, 2026," and the closure limits appear only in a figure, not in the text. Go by the signs at the trail, not by any street-to-street description you see repeated online.
A road closure on the same project gives a sense of the timeline. The southbound lane of Brown Ave south of Queen City Ave. closed on October 14, 2025, and is expected to reopen on October 30, 2026. If that date holds, drivers get that lane back after about a year. The two trail closures are scheduled to last roughly two years beyond it.
The Routes Off the Tunnel Line
All of these routes are away from the launch site and Drop Shaft 7. The details come from the City's trail and park pages and from NH Audubon. They describe each route, not its condition on a given day.
| Route | Length and surface | Where to get on |
|---|---|---|
| Piscataquog Trail | 2.1 miles, paved | West Side Arena, Delta Dental Stadium, Thibault Field, Goffstown Rail Trail |
| South Manchester Rail Trail | 2.4 miles, paved from Beech Street to Gold Street | Runs parallel to South Willow Street, near Nutt's Pond and Precourt Park |
| Heritage Trail, Millyard Riverwalk segment | Paved, open to cycling | Connects toward the Piscataquog Trail |
| Livingston Park, Dorr's Pond loop | 0.9 miles, unpaved | 156 Hooksett Road |
| Derryfield Park | 5K cross-country course, short woodland trails | Bridge Street |
| Piscataquog River Park | Two miles of multi-use trails | North and south trailheads; the north one connects to the Piscataquog Rail Trail |
| Massabesic Audubon Center | More than five miles of trails to Lake Massabesic, plus a 0.4-mile All Persons Trail | 26 Audubon Way, Auburn; open dawn to dusk daily |
If you used the Riverwalk for longer paved mileage, the closest substitute is the Millyard Riverwalk segment connecting toward the Piscataquog Trail, which links up with the Goffstown Rail Trail. Combined with Piscataquog River Park, which connects to the rail trail at its north trailhead, the west side has the city's longest stretch of connected path that the construction doesn't touch. Livingston Park and Derryfield Park work for shorter outings. The Dorr's Pond loop is just under a mile. Derryfield's cross-country course gives you a measured 5K.
Massabesic Holds the East End
The Rockingham Trail runs 3.1 miles, unpaved, from Tarrytown Road to Lake Massabesic. At the lake it connects to another trail network. The Mammoth Road crosswalk is closed, so the City's suggested ways in from Oakland Ave. and Woodbine Ave. matter more now. So does the lake end of the trail.
NH Audubon's Massabesic Center is open dawn to dusk every day. The building is open Wednesday through Saturday, 11 a.m. to 5 p.m. The center's calendar has a "Seed Saving of Native Plants" program on Saturday, October 17. An informal birding outing on October 24 is listed as full. In November the calendar moves indoors, with balsam wreath workshops on November 19 and November 21.
November 8 Puts the City on Foot
The year's biggest day on foot in Manchester is Sunday, November 8, 2026. That's when Millennium Running holds The Elliot Manchester City Marathon, half marathon and relays, starting at 8:50 a.m., and the Manchester City 5K at 9:05 a.m. All of them start and finish in front of Veterans Park at 799 Elm St. The organizer describes a marathon course that goes through the historic Millyard and the North End, then crosses the Merrimack to the Goffstown Rail Trail and returns downtown. The 5K is an out-and-back on the first mile and a half of the marathon course.
The race page still links course maps and turn-by-turn directions labeled 2025. Those materials date from before this fall's work at both ends of the tunnel. If you're running, volunteering or picking a cheering spot, check the organizer's final 2026 route and its traffic advisory before race morning.
Keeping Up With Granite Janet
WMUR's September 30 update described the machine cutting a 12-foot-wide tunnel more than two miles long. In mid-September it was under the CSX tracks, which Pietrasz told the Union Leader was "the most challenging part of the project." Crews stop mining when a train is coming and wait 15 minutes after it passes before starting again. The City's work-progress page has an interactive map of each work site and links to project progress photos. That's the most reliable place to watch for changes before the 2028 reopenings.
Dates for the rest of the season:
- October 16, 8:15 p.m.: Hocus Pocus 2 screening at Derryfield Park, per Visit Manchester
- October 17: Seed Saving of Native Plants at Massabesic Center
- October 30: Anticipated reopening of the Brown Ave southbound lane
- November 8: Manchester City Marathon, half, relays and 5K from Veterans Park
- November 19 and 21: Balsam wreath workshops at Massabesic Center
If the tunnel work has you wondering how a long project like this plays out on your own block, Purple Finch Properties is glad to talk through what's happening near your street and what it means for your home. When you're ready, start with a free home valuation and a conversation with someone who follows these projects closely.