Pedestrians say the intersection where the BU Bridge meets Commonwealth Avenue is “a disaster,” “dangerous,” and “tricky to navigate.”

Credit: Gabrielle Emanuel/WGBH News

Making A More Perfect Intersection

July 10, 2017

A major construction project is just getting underway in Boston: The bridge where Commonwealth Avenue passes over the Mass Pike is being replaced.

From the sky, the intersection looks a bit like an asterisk. Smack dab in the middle of Boston University’s campus, roads are converging from all sides.

It’s where the BU bridge meets Commonwealth Avenue’s eight lanes of traffic. The Green Line chugs down the middle. The Mass Pike runs underneath.

The Massachusetts’ Department of Transportation, or MassDOT, says this big intersection on top of a highway is “structurally deficient.”

Over the course of the next few years, the construction will affect the highway, the T and Amtrak, as well as all the pedestrians, bicyclists and drivers around BU's urban campus.

But before all the detours start, we asked Eran Ben-Joseph, a professor at MIT and the head of MIT’s Department of Urban Studies and Planning, to visit this jumble of streets and see what can be done to make it a more perfect intersection.

Ben-Joseph gave the intersection a grade: a D, or a D+ with grade inflation.

MassDOT has set out to fix it — making a bridge that they say should last 75 years — but Ben-Joseph looks at the intersection on top of the bridge. He says the first step is to answer a question: "Who are you trying to mainly serve in this place?"

Is it the cars? The trains? The bikes?

Ben-Joseph says here, there’s a case to be made for prioritizing the thousands of students and pedestrians who cross the intersection daily. Pedestrians agree, calling the intersection “a disaster,” “dangerous,” and “tricky to navigate.”

Ben-Joseph says you could make this intersection better with just a few little design changes. Here are three of his suggestions:

No. 1: Take space away from cars.

Ben-Joseph says as a driver approaches the intersection, the whole street could get thinner. "If the lane was narrower or there were fewer lanes, the cars would have to go slower,” he said.

No. 2: Change the intersection's surface.

“The material itself is asphalt and it’s dark and it’s black,” Ben-Joseph pointed out. “We often say that psychologically a driver feels this is a place to drive.”

If the designers want to make drivers cautious, Ben-Joseph says, they can paint the intersection a lighter color, they can make it out of bricks, or they can elevate the whole intersection, like a big, wide speed bump.

“Make it with other materials, it feels very different," he added.

No. 3: Landscaping.

Ben-Joseph says things like trees and benches can help.

“The design elements that make the place feel more urban will actually slow down traffic, will slow down the cars," he said.

MassDOT has been studying this intersection for years. Some things will change and some won't.

"This is literally a fight for inches in some cases when you are trying to lay out where a sidewalk should go, where a bike lane should go,” said Jonathan Gulliver, acting MassDOT Highway Administrator. “We are working really hard to reduce the conflict that you see right now.”

Gulliver says on the BU bridge they did make the lanes narrower, but they won’t be doing that on Commonwealth Avenue. Nor is the black asphalt going to change.

As for trees? Kathy Barr, an engineer on the project, says it's hard. “The bridge itself — it’s a concrete steel structure, you can’t add a whole lot of trees and those things.”

But on Commonwealth Avenue on either side of the bridge, some trees have already been added and there are plans to plant more. Plus, Barr says they’ve taken this opportunity to upgrade the bike lanes and add signals just for bikes.

So, it may not turn into the perfect intersection — for pedestrians, cyclists or drivers — but it will be getting better and, soon, it will be structurally sound.

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