Thursday, April 22, 2010

Road closure, Lafayette Square (Main St / Columbia St / Mass Ave), Cambridge

Submited by Jennie

Lafayette Square, the intersection of Main Street, Columbia Street, and Mass Ave, has been transformed into a redesigned intersection and pedestrian plaza due to its complicated driveway. Lafayette Square is located along Massachusetts Ave, Sidney Street and Main Street. Massachusetts Ave is an article of two-way, four-lane and two way cycling roadway. It crosses with Sidney Street and Main Street which is implemented road closure now. Main Street and Sidney Street is a local street which is a two-way. Columbia Street is a two-way two lanes road.

Before the construction, road closure, had started, it exists four intersections around Lafayette Square. Vehicles from Main Street to the intersection of Main Street and Mass Ave need to pass two closed intersections, Main Street and Columbia Street, and Main Street and Sidney Street.
The complicated geometric structure of the roads is easy to result in some impacts:
  • Many movement conflicts located in so short distance are easy to increase incidents.
  • People who drive on Main Street run through Lafayette Square to Mass Ave are easy to ignore the cross road and forget to slow down their speed.
  • People need to wait two traffic lights. It could be easy to result in drivers spend more time to wait and loss their patient.
  • The closed signalized intersections are easy to result redundant lost time and worsen service level.

Therefore, the City of Cambridge planed to redesign the roadway and close Main Street form the intersection of Main Street and Columbia Street to the intersection of Main Street and Mass Ave. The construction started in early 2005, and was completed in summer 2008. The construction is to implement road closure from intersection of Main Street, Columbia Street, to the intersection of Main Street and Mass Ave, and reconstruct the roadway and new sidewalks. The project used bollards and gateway pier to close the road.
From Main Street to Mass Avenue or from Columbia Street to Mass Avenue, drivers have to make a detour by Sidney Street. The construction also supplies pedestrians and bicyclists a safety space to access. Main feature of the construction is to provide the roadway service and improve safety of the corridor for pedestrians, bicyclists, and vehicles. They also set some chairs and tables to supply people a leisure place.

The road closure of Lafayette Square has the following features:
  • Make the intersection easy for all modes to use.
  • Improve accessibility and safety for cyclists and pedestrians.
  • Create a new community plaza.
  • Minimize impacts on parking and loading.

The construction also brings some problem about traffic signal and roadway that would have to be continued to take care. The old traffic lights and land marking do not remove from Mass Ave that will confuse drivers’ follow. The marking on the roadway from Columbia Street to Main Street doesn’t use the standard frame. It is a low visibility marking for user to follow.

In summary, this project achieves its goal to improve and provide a safer environment for vehicles, cyclists and pedestrians by road closure. The construction is not only focus on traffic safety but create a new community plaza. Although it will make people have to make a detour from Main Street and Columbia Street to Mass Ave it reduce traffic confliction in this area that is the best objective for a traffic engineering designer.


  1. Better knowledge of the prior configuration would have been helpful. The traffic signal used to be 3 phase (one each for Mass Ave NB, Main, and Columbia). Columbia used to go straight through, and Sidney didn't.

    I think the main objective was to create a pleasant, public place where there once was a lot of pavement. Traffic operations and safety wasn't the main point. The fact that the space created is beautiful and well used, and that traffic still flows, indicates success.

    No comment about the "right turn only" restriction for the westbound approach on Sidney St?

  2. These are certainly selling points real estate agents use in the selling process. My friend does real estate properties in Weston MA, and I know she loves to mention the safety of travel for kids, and family members.