Union Square Early Action Plan

The Union Square Early Action Plan has been developed with four primary goals:

  • To relieve vehicle congestion in Union Square
  • To improve safety and accessibility
  • To perform minor water and sewer utility upgrades
  • To facilitate a safe, efficient traffic management plan for the upcoming larger sewer separation project scheduled for 2017-2018

Learn more about the Union Square Early Action Plan in the tabs below.

  • Latest Updates & FAQ (8/3/2017)

  • Traffic Pattern Change

  • Plans & Presentations

  • Past Updates & FAQ

Updated 8/3/2017


Q: What’s happening in Union Square?

A: On July 29, 2017, Prospect Street and Webster Avenue were converted to accommodate two-way traffic between Prospect Street/Webster Avenue and Somerville Avenue.  Newton Street has been modified to restrict through vehicle traffic between Webster Avenue and Prospect Street. Click on the Traffic Pattern Change tab above for more information, including a diagram of the changes.

This work has included several phases: changing and/or removing existing signals, repaving portions of streets in and around Union Square, and repainting lane markings.

There are other projects within Union Square that are also in their early phases. For details on those projects, please refer to the following pages:

Q: What work is left to be done?

A: While all major road markings and painting had been completed prior to this change, there is still some additional minor painting to be done. This work will begin on the week of August 7, and generally includes green markings for bicyclists, including bike boxes, two-stage left turn queue boxes, and green markings in conflict zones. The striping of bicycle facilities and parking lanes will also be completed on Washington Street, between Mansfield Street and Somerville Ave. We will be installing reflective posts to delineate the bicycle lanes on Washington Street and make pedestrian crossings on Somerville Avenue and Webster Avenue more visible. A flashing beacon will be installed at the midblock crosswalk across Somerville Avenue.

Construction barrels along the centerlines of Prospect Street and Webster Avenue, as well as at the intersection of Prospect Street/Newton Street, will be removed once the new traffic pattern is well established, and we feel it is safe to do so. Additional blinking signage will be installed at the corner of Webster Avenue and Newton Street to reinforce the message that access to Newton Street is intended for abutters only.

We are also constantly monitoring traffic conditions and will be making changes to signal phasing and timing to help improve safety and operations at the three intersections affected by the traffic pattern change. Signal timing changes will be made on Prospect Street at Somerville Avenue on Friday, August 4. We will monitor how these changes affect traffic flow on Prospect Street and the other approaches to the intersection, and consider additional adjustments as necessary. 

Q: This project is supposed to help improve traffic in and around Union Square. How, and when, will that happen?

A: Switching Prospect Street and Webster Avenue to two-way adds mobility options for motorists and bicyclists.  The City conducted multiple traffic studies to inform this proposal.  An initial planning study for the two-way concept was conducted in 2007-2008, and the advanced traffic engineering was performed in 2014.  New traffic data collection occurred in 2016 prior to the start of construction to validate the traffic models and calibrate them for current conditions.

The City’s traffic studies found that in the heart of Union Square, hundreds of vehicles must use Prospect Street and Somerville Avenue to access Bow Street to continue north and west of Union Square; enabling two-way traffic on Webster Street allows motorists the option of avoiding Somerville Avenue altogether. Similarly, Somerville Avenue westbound traffic can use Prospect Street, rather than Webster Avenue, to go south toward Cambridge.  We have estimated that 50%-60% of westbound traffic on Somerville Avenue between Prospect Street and Webster Avenue may be able to avoid this segment in the future, resulting in less congestion and delay for motorists.

Two-way traffic is also calmer traffic, resulting in safer vehicle speeds, which helps reduce the number and severity of crashes.

Finally, converting Prospect Street and Webster Avenue to two-way traffic will help facilitate traffic detours during the Somerville Avenue Sewer Separation project, and the GLX. 

Q: Prospect Street is really backed up heading into Union Square. What’s being done about that?

A: Since the traffic change took effect, we have been closely monitoring traffic in this area, across several departments (Traffic & Parking, Police, Transportation & Infrastructure). Understanding and utilizing the new pattern will take some time for motorists and bicyclists to become accustomed to, and we will continue to deploy resources to try to quickly assist in these changes. Police details have been stationed at major intersections to try to alleviate confusion and congestion, and as of August 2, we have installed additional message boards designed to direct motorists to Webster Avenue to alleviate the congestion on Prospect Street.

We are also working to have GPS navigation apps such as Google Maps and Waze updated to reflect the two-way operations so that motorists using GPS are not automatically sent down Prospect Street. In the meantime, we are working with our design team to develop small changes to the signal timing at Somerville Avenue/Prospect Street that will help to relieve some of this congestion. 

Among other factors, we made this change in the traffic pattern over the summer months, when traffic is at a low, to allow us to make changes and adjustments as necessary before school begins in September. We will continue to monitor and make any necessary adjustments in the coming weeks.

IMPORTANT TRAFFIC PATTERN CHANGE INFO: Prospect St., Webster Ave., to Convert to Two-Way Streets as of  July 29, 2017

NOTE: Click on the Latest Updates & FAQ tab above for the most recent information on the traffic pattern change and Early Action Plan.

Beginning on Saturday, July 29 (weather permitting), both Prospect St. and Webster Ave. will be converted to accommodate two-way vehicle and bicycle traffic. Currently, Webster Ave. is one-way from Somerville Ave. to the intersection with Prospect St., while Prospect St. is one-way from Webster Ave./Concord St. into Union Square. The switchover is the culmination of a multi-year “Union Square Early Action” planning project, for which construction officially began in spring 2017.

Overnight on Friday, July 28, construction crews will paint new markings on both streets prior to changing traffic signals on Saturday morning. All work is expected to be complete between 2 and 4 p.m. on Saturday, at which time the new traffic pattern will take effect. Police details will remain in place for a period of at least one-to-two weeks as commuters adjust to the change.

Important Things to Know About the Traffic Pattern Change:

  • Both Prospect St. and Webster Ave. will permanently accommodate two-way traffic, both for bicycles and for vehicles.
  • A drop-off lane for St. Joseph’s Church and Prospect Hill Academy will be maintained.
    • Parking will be eliminated on this side of the street.
  • Newton St. will no longer be a through street, but will be accessible for abutters only.

Prior to the traffic pattern change, electronic signage will be placed in several key locations in Somerville and in Cambridge, alerting motorists of the upcoming change. Once the lane markings have been installed and new traffic signals activated, cones, barricades, and police details will be in place temporarily as motorists, bicyclists, and pedestrians gain experience with the new pattern.

Preview of linked traffic plan PDF

Q: What is happening with the construction in Union Square?

A: There are several projects ongoing in and around Union Square. Most of the work you’re likely noticing as of May, June and July 2017 is related to the Union Square Early Action project. Through this project, a culmination of a multi-year community process, the primary goal is to improve safety and accessibility through Union Square by switching the traffic pattern on Prospect Street and Webster Avenue, between the intersection of these two streets and Somerville Avenue, from one-way to two-way. 

This work has included several phases: changing and/or removing existing signals, repaving portions of streets in and around Union Square, and repainting lane markings.

There are other projects within Union Square that are also in their early phases. For details on those projects, please refer to the following pages:

Q: When is the traffic pattern switch going to occur? What needs to happen beforehand?

A: The switchover is scheduled to occur on the afternoon of Saturday, July 29t, weather permitting. Overnight on Friday, July 28, crews will paint the new markings on both Webster Ave. and Prospect St. Final changes to traffic signals will be made on the morning of July 29.

Q: How will the streets change to accommodate two-way traffic?

A: On Webster Avenue, parking will be removed on one side of the roadway to make room for a northbound travel lane.  Drop-off zones and parking will be retained on the west side, adjacent to St. Joseph’s Church and Prospect Hill Charter School .

On Prospect Street, one northbound travel lane will become a southbound travel lane.

Newton Street between Webster Ave. and Prospect St. will no longer be a through street. It will be open for abutters only.

Q: What measures are in place to ensure safety after the new pattern is in place?

A: New signal equipment has been installed at the intersections of Webster Avenue/Prospect Street, Somerville Avenue/Prospect Street, and Washington Street/Somerville Avenue/Webster Street.  In the weeks following the switchover, the yellow center line will be enhanced with traffic cones, and police details will be in the area for several weeks to make sure traffic runs smoothly.

Q: What is changing on Newton Street?

A: As Webster Avenue is becoming two-way, there is an increased potential for cut-through traffic on Newton Street from Webster Avenue to Prospect Street.  In order to keep through traffic off this residential street, the segment of Newton Street between Everett Street and Prospect Street will become one-way towards Webster Avenue. All vehicle traffic on Newton Street must use Everett Street to access Webster Avenue, and no access to Prospect Street will be provided. 

Bicyclists will be able to use Newton Street as a through street in either direction.  Pavement markings will guide bicyclists though the roadway.

Q: What are the benefits of the switch to two-way traffic?

A: Switching Prospect Street and Webster Avenue to two-way adds mobility options for motorists and bicyclists.  In the heart of Union Square, hundreds of vehicles must use Prospect Street and Somerville Avenue to access Bow Street to continue north and west of Union Square; enabling two-way traffic on Webster Street allows motorists the option of avoiding Somerville Avenue altogether. Similarly, Somerville Avenue westbound traffic can use Prospect Street, rather than Webster Avenue, to go south toward Cambridge.  We have estimated that 50%-60% of westbound traffic on Somerville Avenue between Prospect Street and Webster Avenue may be able to avoid this segment in the future, resulting in less congestion and delay for motorists.

Two-way traffic is also calmer traffic, resulting in safer vehicle speeds, which helps reduce the number and severity of crashes.

Finally, converting Prospect Street and Webster Avenue to two-way traffic will help facilitate traffic detours during the Somerville Avenue Sewer Separation project, and the GLX. 

Q: How will this affect pedestrians?

A: A new mid-block pedestrian crossing will be added on Somerville Avenue between Prospect Street and Webster Avenue.  This crossing will have a median refuge island (which is already present) and a flashing beacon that will alert motorists to the presence of pedestrians crossing the street.

Secondly, pedestrian phasing at the intersections of Webster Avenue/Prospect Street, Somerville Avenue/Prospect Street, and Washington Street/Somerville Avenue/Webster Street will become concurrent with adjacent vehicle traffic. Pedestrians will get a four-second head start before adjacent traffic gets a green light so that pedestrians can begin crossing before turning vehicles enter the crosswalk.  This treatment reduces pedestrian delay at intersections my reducing the overall signal cycle length and allowing pedestrians to cross multiple legs of an intersection faster.  This style of pedestrian crossing phasing is seen throughout Cambridge and in parts of Boston, as well as many other cities across the country.

Q: Will there be bike lanes in both directions on both streets?

Unfortunately, both streets are too constrained to allow bicycle lanes in both directions.  Webster Avenue will have a bicycle lane in the southbound direction, and Prospect Street will have a bicycle lane in the northbound direction. Bike boxes and left-turn queue boxes will be provided at the intersections of Somerville Avenue/Prospect Street and Washington Street/Somerville Avenue/Webster Street to help facilitate bicycle turning movements in the heart of Union Square.