Challenge
The intersection of Hampshire Street and Cambridge Street in Cambridge, Massachusetts’ busy Inman Square presented a familiar challenge for cities. Due to its low-angle skew, the intersection expanded over 250 feet, creating a confusing and chaotic environment for anyone passing through. With almost as many bicycles as cars on some approaches—not to mention pedestrians and buses—accommodating everyone was nearly impossible. With no obvious conventional solution, local advocates recognized the need to innovate, which led them to Kittelson’s Boston office.
Solution
While previous efforts to fit a traditional roundabout in Inman Square failed due to a lack of space, Kittelson identified a solution using a pair of mini-roundabouts connected in the middle. The resulting peanut-shaped, protected mini-roundabout design led the Boston Cyclists’ Union to coin the term “peanutabout.”
The elongated roundabout design turned sharp corners into smooth turns to create a more comfortable design for everyone. With bike lanes along the perimeter and raised crosswalks, cyclists and pedestrians have safer, designated routes that are more visible to drivers.
The Outcome
Designing the First Peanut-Shaped Roundabout
The unique roundabout design offers benefits to many roadway users:
- For Cyclists: Inspired by learnings from Scandinavia, Denmark and the Netherlands, we designed a protected bike lane on the outside of the roundabout.
- For Trucks: Using bumps in the road that only larger vehicles can cross, we designed a flex space for trucks for smoother turns.
- For Pedestrians: Raised crosswalks help give pedestrians priority as they cross the intersection. As with bicyclists, pedestrians only intersect with vehicles for short periods of time and at a few points in this design.
- For Residents: Smart urban design helps create more space for things like cafes and public seating.
While the City ultimately advanced a different design, our design demonstrated that roundabouts can work in tight spaces and has inspired unique roundabout shapes in other places, like this one.
