Bicycle Safety Guide and Countermeasure Selection System


Contraflow Bicycle Lanes on Urban Streets

Cambridge, Massachusetts

Cara Seiderman, Transportation Program Manager, Cambridge, MA


Cities like Cambridge, Massachusetts, that have extensive one-way street systems, can be very frustrating for bicyclists to maneuver because it takes longer to detour and because the alternative routes can be more stressful or less safe. In addition, because of the inherent greater flexibility of bicycle travel, many bicyclists will simply ignore the one-way restrictions and travel against traffic, particularly when traffic volumes and speeds on the preferred route do not present a deterrent.

Sign indicating contraflow bike lanes on Scott Street.

Sign indicating contraflow bike lanes on Scott Street.

There are two options available to accommodate bicyclists on one-way street systems. Many cities and towns in Europe explicitly allow bicyclists to travel in both directions on one-way streets. This usually occurs on very narrow streets with very slow traffic, typically in the core areas of older cities and towns. Another option is creating specific designated facilities to permit bicyclists to travel in the opposite direction. The contraflow bike lane is a designated facility that allows bicyclists to travel against the flow of motorized traffic on a one-way street.

There are safety concerns associated with contraflow bike lanes. Motorists and pedestrians often do not expect bicyclists to be traveling in the opposite direction of traffic on one-way streets, especially at driveways, alleys, and parallel parking. However, contraflow bike lanes have been used successfully in some cities in the United States (such as Boulder, Colorado; Eugene, Oregon; Portland, Oregon; and Madison, Wisconsin). Building on evaluation criteria developed for Eugene, the City of Cambridge considers the following criteria when evaluating a potential contraflow lane location:

In addition, the following features shall be incorporated into the design of the street with the contraflow lane:

It is preferable to have a separate bike lane in the direction of motor vehicle traffic, striped as a normal bike lane. Where the roadway width does not allow this, bicyclists will have to share the road with traffic.


There now are four contraflow bicycle lanes in Cambridge: on Concord Avenue between Follen Street and Waterhouse Street (often referred to as "Little Concord Avenue"); on a short portion of Waterhouse Street off of Mass. Avenue; on Scott Street between Beacon Street and Bryant Street; and on Norfolk Street south of Broadway. These contraflow lanes meet the criteria detailed above, although Norfolk Street was somewhat of an exception in that not many bicyclists were riding against traffic on this street.

Concord Avenue
In 1994, a major street renovation project changed in the street pattern in the area of Arsenal Square. This route is a direct connection for east-west travel in the city as well as a main route to access different locations on Harvard Universitys campus. The contraflow bike lane on Concord Avenue not only provides the most direct connection for bicyclists, but also allows cyclists to avoid riding on a street with heavy traffic and no space between the travel lanes and the parking lanes, as well as to avoid riding through an underpass where cars reach speeds of up to 50 mi/h, despite the citywide 30 mi/h speed limit. Large numbers of bicyclists were already traveling in both directions on this short residential block, and there were only two driveways for single-family residences along the street, so it was an ideal location for the direct bicycle connection that could be safely provided with a contraflow bike lane.

Concord Avenue contraflow bike lane.

Concord Avenue contraflow bike lane.

A five-foot wide contraflow bicycle lane was created with two solid white lines and bicycle symbols and arrows at very frequent intervals. White paint was used rather than the yellow normally used to separate the directions of traffic in order to allow motorists to cross the bike lane to park in the parking lane between the curb and the bike lane. A stop sign for bicyclists was put up at the end of the block so that bicyclists would look for traffic before proceeding across the street.

Signs were installed on the approach to the intersection, which is more of a bend in the road than a conventional intersection, to tell motorists to proceed slowly. The street is U-shaped which only serves residents along the street, with very low traffic volumes (fewer than 1,000 vehicles per day).

Scott Street
Sewer construction and roadway paving on Scott Street offered the possibility of implementing traffic calming. Scott Street offers a direct connection between a minor arterial that is one of the areas most-used bicycle travel corridors and Harvard University, Harvard Square, and other destinations. It is a wide one-way street with little-used parking on both sides. A contraflow bike lane was marked and blue thermoplastic included, reminding motorists to look for bicyclists and not to drive in the bicycle lane. A sign was included, stating "Do Not Enter Except for Bicycles." Traffic volumes were less than 2,000 vehicles per day.

Norfolk Street
One block of this one-way street was striped as a contraflow lane to allow bicyclists to avoid an arterial street without shoulders or bike lanes and with large traffic volumes, including trucks. Norfolk Street traffic volumes were below 2,000 vehicles per day. A sign with a graphic representation of the contraflow lane was installed at the entrance to the street. Blue thermoplastic was added to each end of the lane to call attention to its presence.

Evaluation and Results

No formal evaluations have been carried out for these streets, but the safety benefits likely include reduced wrong-way riding and decreased sidewalk riding. The contraflow lanes also offer bicyclists the option to use lower speed, lower volume streets to access their destinations. City staff have observed that bicyclists are continuing to use the streets in both directions and are using the designated contraflow lanes.

On Concord Avenue, some bicyclists have been observed riding in the contraflow lane in the direction of traffic, despite the frequent occurrence of arrows. Anecdotal comments are that the lane has bike symbols, so it seemed to those traveling the wrong way that they were supposed to be in that lane. There is also a sight-line issue on Concord Avenue created by a combination of the angle of the street and a private property fence. Regular users of the street expressed concerns and additional signs were put up to remind motorists to watch for bicyclists.

Before and after bicyclist counts conducted on Scott Street showed an increase of bicyclists riding against the direction of traffic in the contraflow lane following its installation. Given origins and destinations in the area, it was expected that more people would be using the contraflow lane in the morning peak period, and this was affirmed in the data. On Concord Avenue, counts showed that there were about the same number of bicyclists in both directions of travel before and after the installation of the contraflow lanes.

Since the installation of contraflow lanes in Cambridge, other cities in the United States have implemented their own contraflow lanes. Today, at least 14 citiesincluding Baltimore, Maryland; Washington, D.C.; Minneapolis, Minnesota; Austin, Texas; Boise, Idaho; and New York Cityhave installed contraflow bike lanes with positive results. Nearby Brookline, Massachusetts, implemented two contraflow lanes on Netherlands and Parkway Roads in 2009. It is estimated that 150,000 bicyclists used Brookline's contraflow lanes between 2009-2012 without any reported incidents. In Cambridge, it is estimated that over one million bicyclists have used the four contraflow lanes without any reported incidents. In 2012, AASHTO included discussion of contraflow lanes in its Guide for the Development of Bicycle Facilities, 4th edition.

Conclusions and Recommendations

Contraflow bike lanes can be used successfully in circumstances similar to the ones described here. There may be additional designs or circumstances that would merit testing as well.

Pavement markings and signs should be thought through carefully in the design of contraflow bike lanes. It is preferable to implement the lane when longer-lasting pavement marking materials can be installed (thermoplastic or in-lay tape). Otherwise, a strict maintenance program to keep paint highly visible will be required. Bicycle symbols and arrows should be marked at frequent intervals (far more frequently than standard AASHTO recommendations), and implementing agencies should consider adding color in the lane (in 2011, FHWA issued interim approval for the optional use of green colored pavement). Signs should be installed wherever motorists would be approaching the street, such as at the beginning of the intersection and at intersecting roads or major driveways.

Where there is room for bike lanes on both sides of the street, they should be included to clarify where cyclists should travel. If there is no room for a full bike lane, other pavement markings or signs should be considered to clarify direction.

Costs and Funding

In general, the costs for implementing a contraflow lane are fairly straightforward and easy to calculate when they involve standard pavement markings and signs. The costs would increase somewhat from a standard bicycle lane because it is preferable to use more frequent bicycle symbols and arrows as well as more signs. Additionally, some signs might be custom-made rather than standard. Costs would increase if colored thermoplastic paint is used.

Table of sample costs for the materials needed to install a contraflow bike lane.


Cara Seiderman
Transportation Program Manager, Cambridge, MA
Environmental & Transportation Planning
Community Development Department
Cambridge, MA 02139