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In the most complicated stretch of the Green Line extension, cyclists will rise above it all

The pedestrian/bike bridge being installed as part of the Green Line extension.
The pedestrian/bike bridge being installed as part of the Green Line extension.John Tlumacki/Globe Staff

SOMERVILLE — Right now, this industrial strip in the Inner Belt district is a thicket of concrete pillars, steel beams, ramps, and half-finished viaducts. But in a little more than a year, these elevated tracks will finally carry MBTA trolley riders, the conclusion of the decades-long effort to extend the Green Line north into Medford.

And another group of travelers, these of the two-wheeled variety, will get their own long-awaited skyline cruise, as well, on a viaduct serving as the final link in a nearly 15-mile stretch that will let cyclists and pedestrians traverse between downtown Boston and as far away as the northern end of the Minuteman Commuter Bikeway in Bedford — almost always separated from car traffic.

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The 1,400-foot viaduct will offer cyclists a striking, hard-won perch, rising at one point some 50 feet above the surface and the nest of rail tracks below.

“It’s going to be a great vantage point to see a lot of cool stuff — for seeing a lot of transit operations, a good view of the city,” said John Dalton, the Massachusetts Bay Transportation Authority’s Green Line project manager. “For bikers and joggers and walkers, it will be worth the effort.”

It will indeed take some effort to get uphill, as the viaduct will require a steep climb, although the gradient, at about 4.8 degrees, meets Americans with Disabilities Act standards, Dalton said. That kind of incline won’t be unfamiliar to seasoned cyclists: The North Bank bike and pedestrian bridge in Cambridge is similarly sloped, and some of the hills through Somerville are much more challenging.

After years of starts and stops, the Green Line extension is scheduled to open for passenger service late next year, with seven new stations and two branches. The Union Square branch is likely to open before the longer branch out to Tufts University, though the schedule is still being worked out. About 650 people are working on the project, with construction happening all along the 4.7-mile route, and the new stations beginning to take shape.

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No part is more complicated than in the Inner Belt, the industrial sector north of Monsignor O’Brien Highway. Here, elevated railways will bring trains across the Fitchburg Line’s commuter rail tracks just north of the relocated Lechmere Station, then split into separate branches, including a viaduct that makes a long loop as it drops toward the surface and heads west. In the same area, other tracks feed into a nearby Green Line maintenance facility, and important utility structures are close by.

“It’s definitely the confluence of all major components of the project, happening in that narrow stretch,” Dalton said. “I call this the spaghetti bowl of the project, just because there are so many things interweaving with each other.”

But the highest piece of infrastructure will the last leg of the Somerville Community Path, which will connect to Davis Square, Alewife, and the Minuteman bike path to Bedford but currently cuts off in central Somerville. It will be completed as part of the rail project, running near the tracks for much of the route and sloping upward on the final stretch toward Lechmere.

The new viaduct has been designed to travel above the Green Line tracks in the Inner Belt because it would have taken too steep an incline to put the trolleys above. Not that cycling advocates are complaining: Galen Mook, director of the Massachusetts Bicycle Coalition, said it will feel liberating for cyclists to rise above the snarl.

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“It gives you a whole new sense of wonder that you’re above some of that tricky and nasty infrastructure,” he said, comparing it to traveling under heavy infrastructure like highway or train bridges. “When you’re up, you are removed, whereas on the flip side, if you go under it, you feel stuffed down by it.”

Dalton warned there are some important hurdles ahead for the Green Line extension. Workers still need to drill into the ground in some areas, which opens up potential complications with utilities. There could be hiccups in tying the new railway into the existing tracks at the end of the line. And the pandemic has caused supply-chain issues that Dalton described as the biggest risk to the timeline.

Still, the extension has moved along steadily the last two years, remarkably so for a project that was on life support just a few years ago. State officials abruptly halted the project in 2015 when costs were projected to spiral as much as $1 billion over budget, before firing contractors and moving to simplify the designs to save money.

The community path viaduct was on the chopping block to reduce costs, and it looked for a time as if cyclists would be directed to busy streets on the final stretch toward Lechmere. But the new contractor, GLX Constructors, said it could build this leg of the path and stick to the $2.3 billion budget.

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Some of the path’s biggest champions are disappointed, however, that it will be only 10 feet wide. It should have been wider to accommodate what will probably be a large number of users, especially since the slope of the viaduct will cause some cyclists to travel at high speeds, said Lynn Weissman of the nonprofit Friends of the Community Path.

“We had hoped for more,” she said. “At least it will be a nice view.”


Adam Vaccaro can be reached at adam.vaccaro@globe.com. Follow him on Twitter at @adamtvaccaro.