Monday, May 3, 2010

One-way Street With Reversing Direction, Shawmut Ave from Herald Street to Mass Ave

By: Caitlin Glass

One-way Street with Reversing Direction, Shawmut Avenue from Herald Street to Massachusetts Avenue

Shawmut Avenue in the South End of Boston is a one-way street with reversing direction. The map above displays where the street changes its one-way direction, with the bolded blue line depicting west bound travel and the bolded black depicting east bound. As is visible from the map, Shawmut Avenue is west bound for seven blocks between Massachusetts Avenue and West Dedham Street, east bound for five blocks between West Dedham Street and East Berkeley Street, and west bound again for about two blocks between East Berkeley Street and Herald Street. The map below depicts a satellite view of one of these changes, at West Dedham Street.

Shawmut Avenue is in a fairly residential part of the city, with commercial buildings throughout as well. It is a two-lane, one-way with reversing direction street that has residential parking on both sides of the street but only in one direction. The portion of the street near Massachusetts Avenue is two lanes with a dashed center line that clearly distinguishes the two lanes. The part of the street near Herald Street is wide enough to fit parking on both sides of the street and two cars next to each other, but lacks a dashed center line.

Traffic Calming: Goals, Actual Use, Intended Use, and Design
The definition of traffic calming, according to the Institute of Traffic Engineers (ITE), is "the combination of mainly physical measures that reduce the negative effects of motor vehicle use, alter driver behavior and improve conditions for non-motorized street users."

In the South End of Boston, particularly Shawmut avenue and a few surrounding streets, the traffic calming measure of alternating one-way directions on a street is used. The goal of this strategy is to reduce conflicts, reduce traffic volumes and speeds, and manage traffic patterns. Instead of the traditional one-way street grid for a residential area, motor vehicles are required to turn left or right at every five intersections or so. By reversing the direction of one-way traffic every few intersections, it discourages drivers from using it as through street. It's considered a sign-based control measure because all it really takes to make the street one-way is signs pointing out it is one way and having "do not enter" signs in the opposite direction.

The intended use of this measure is to reduce cut-through traffic and overall volume, as well as to reduce traveling speeds.

The actual use that I observed was what seemed to be fairly low traffic volumes, around 3pm on a Monday, and speeds within the posted limit of 30 mph. As a driver, it is frustrating to travel on a roadway that constantly forces you to turn left or right onto another road in order to continue on in the direction you are traveling. Because of this, it seems the alternating direction of one-way on this street is effective in directing through traffic onto a parallel roadway that was designed for higher volumes of traffic. However, I observed some vehicles speeding up in between intersections, then slowing down quickly for the all-way stop. Some vehicles also failed to come to a complete stop at the intersections, which can be dangerous for pedestrians, cyclists, and vehicles traveling on the cross street.

The design properties implemented in this traffic calming measure are simply using stop signs, "do not enter" signs, "all way stop" signs, and "drive slow" signs incrementally throughout the street. Also, parking on both sides of the street acts as a traffic calming measure in itself, because it causes a bit of friction and slows speeds. These parking spaces narrow the roadway and thus help in keeping travel speeds within the desired range. Crosswalks at every intersection are also helpful as it gives priority to pedestrians and makes the area feel more residential.

In terms of actual footage, Shawmut Avenue is broken up in one-way sections as follows:
  • from Massachusetts Avenue and West Dedham Street = 2000'
  • from West Dedham Street and East Berkeley Street = 1500'
  • from East Berkeley and Herald = 1000'
Between Massachusetts Avenue and Herald Street, Shawmut Avenue changes direction 3 times. With an estimated length of 4500 feet (as a takeoff from the first map shown), the sections a driver can use before being forced to turn are only 1500 feet long, on average.

This traffic calming measure of alternating the direction of the one-way streets has been fairly successful in the area. Motorists are less likely to use Shawmut Avenue as a cut-through street because it is inconvenient to travel down more than a few blocks, as it forces drivers to take a left or right and switch onto another roadway. Surrounding streets implement the same alternating one-way strategy. For example, West Concord Street changes its one-way direction as it intersects with Shawmut Avenue, as does Rutland Street. Using this traffic calming measure on streets in the area does an even better job at decreasing traffic volume in the area and discourages non-residents to use the roadway. Alternating the direction of the streets can be confusing if you don't know the area and provides more of an incentive to use the street only if you know your destination and which cross street it intersects with.  

Effect on Pedestrians 
It is safer for pedestrians because it allows them to only have to look in one direction while crossing and they only have to cross one directional stream of traffic, as opposed to other two-way streets where the pedestrian will have to look both ways and cross two traffic streams. Studies have shown that reducing two-way streets to one-way typically reduces pedestrian crashes.

Other Traffic Calming Measures
At the intersection of West Brookline Avenue and Shawmut Avenue there is a traffic light and as it is a school zone the speed limit is 20 mph. There are also posted yellow signs with a picture of a person running and the words "Drive Slow", as shown in the picture below.

Another interesting traffic calming strategy is bulb-outs, as seen in the picture below.

These bulb-outs narrow the roadway, decreasing traffic speeds, and allow pedestrians a shorter distance to cross the street. It makes crossing safer for pedestrians as they have to go a shorter distance and the bulb-out makes it easier for motorists to see the pedestrians that are waiting to cross.

Although this strategy of traffic calming seems to be fairly successful, especially in reducing traffic volumes, there are a few problems to consider and some slight changes to be made:
  • One downfall to this type of traffic calming is that although they may be effective in decreasing traffic volumes, speeds can increase as drivers are channelized through the street. This potential for high speeds can be a large problem especially in residential areas, and if the street or lanes are overly wide can add to this problem
  • Another downside to one-way streets is increased travel distances for motorists and cyclists, as well as increased confusion especially for non-local residents. Although this is a side effect of the traffic calming measure itself and is part of the reason why it works, it is something that motorists could potentially complain about
  • Another area of concern is the lack of one-way exemption for bicycles. Although there aren't any designated bike lanes or sharrows on this street indicating a space for cyclists, there should be some acknowledgement in the way of a sign that lets drivers and bikers know that cyclists are exempt from the direction of motor vehicles. While observing the street I noticed several bikers traveling against traffic, despite there being a lack of signs indicating it was legal to do so