One-way vs. two-way streets

The citizens of Richmond, Va., last year had a vigorous discussion about converting downtown one-way streets into two-way streets.

The Urban Richmond blog took some time to break down some of the arguments for and against such a conversion. The arguments are nowhere near cut-and-dried either way.

The blog divides up the arguments like this:

Reasons for converting to 2-way streets:

  • Slower traffic speeds.
  • Decrease “Vehicle Miles Traveled” by eliminating indirect routes (driving around the block to get to your destination).
  • Increased access to businesses.
  • Possibly: safer for pedestrians.

Reasons for maintaining 1-way streets:

  • Conversion is very costly.
  • 1-way streets allow for more cars, thereby decreasing congestion.
  • Easier than 2-way streets to time stoplights (timed lights improve traffic flow and decrease idling (& therefore pollution)).
  • Fewer turn prohibitions.
  • More on-street parking.
  • Possibly: safer for pedestrians.

The author of the blog lamented that so much of the information for or against conversion to two-way streets was highly partisan. But he did link to some studies he thought were more balanced:

Downtown Streets: Are We Strangling Ourselves on One-Way Networks?

Published by the Transportation Research Board, the article … argues that 1-way street networks provide many more possible types of street intersections. … 1-way street networks increase the variety and kind of conflict points creating more confusion for pedestrians and motorists.


This article says, “The additional turning movements for a one-way street network increase the occurrences of vehicular-pedestrian conflicts at any given intersection, and also result in a system-wide increase in vehicle mile of travel (VMT) as compared to a two-way street network.” In other words, you have to turn more on a 1-way street network, and therefore have more chances of running over people.

No Two Ways About It: One-Way Streets are better than Two-Way.”

The most convincing evidence produced in this paper by The Center for the American Dream of Mobility and Homeownership is that pedestrians were hit more frequently after streets were converted to 2-way in several downtowns in the U.S.

Urban Richmond would like to see more empirical data for the conversion of one-way streets to two-way, and so would I. Are there any more studies that any can point out that can help a citizen think rationally about the topic of pedestrian safety? And what do you think?

— Photo by z6p6tist6 on Flickr


  1. This thread has a current discussion and has three different expert opinions on the question of pedestrian safety

    The comments section encapsulates the beef with the DMP process:

    The DMP does not address pedestrian safety. It ignores the areas that need the most help (ie existing wide, two way, high speed streets such as Broad or Belvidere, or existing one ways that block access to the river such as Byrd, Canal, or lastly anywhere there is an exit / entrance ramp to a freeway) The zealot traffic consultant was hired to have one answer and provided the only solution that was required by the Venture Richmond business folks to fix all those “pedestrian safety problems” downtown… convert ALL downtown streets to two way.

    First, any legitimate traffic engineering consultant would determine where the “pedestrian safety problems” exist by analyzing 3-5 years of pedestrian crash data downtown to better understand the problem and help target workable solutions. Ask them for this crash analysis. From my experience working with this crash data in downtown Richmond, you would find most of the ped crashes occur on wide two way streets (Broad, Belvidere, Main etc) or inn areas that have high speeds and few gaps. A good consultant with the best interests of downtown Richmond would target pedestrian safety countermeasures to mitigate the crash trends (1st provide more gaps for pedestrians, 2nd narrow the crossing exposure, and 3rd slow travel speeds)

    Ultimately, this is easier to do in the existing one way patterns than an expensive conversion to two way. The 5th & grace model is the superior pedestrian street model for downtown. This alternative, though presented to the zealots, was exclude as a workable alternative for no reason. Instead the zealots spend their entire document justifying their position for conversion. The zealots get paid for selling snake oil in the form of fixing our “pedestrian safety problems”. I’ve lived downtown, work downtown, play downtown. Never had any problems crossing a street, have you? It’s ridiculous that those two-way zealots want us to spend +$30-40M to fix our problem. It is an opportunity cost to downtown being billed as the next savior and it is totally misdirecting funds with zero benefit to pedestrians, transit, bikes, or motorists.

    I could go on about the short blocks causing gridlock in a two way pattern, the parking eliminated, the left turns being prohibited, the double parking or utility repairs blocking streets on infrastructure over 100 years. One-ways handle all that better.

    We have a very good grid (if it is preserved and not built over through superblocking) and a pedestrian friendly environment that could be upgraded through good form based coding (a strength of Dover Kohl). But dump that traffic consultant and the planners utopian vision of two ways everywhere. It makes for a great Norman Rockwell painting; but it’s a poor choice for downtown Richmond. A 5th & Grace vision does it better.


  2. I’m posting the last message based on a Richmond VA centric viewpoint. I believe the comments and the passion for the issue may be useful to Fort Wayne

    You may be able to use a google map of downtown Richmond to see some of the streets referenced.


  3. Benefits of One-Way Couplets

    Studies were conducted from the 1930’s to the 1970’s of ‘before’ and ‘after’conditions as cities switched from two-way to one-way streets. Almost universally they found that one-way streets had 10-20% lower accident rates than when previously two-way. Most significantly, pedestrian accidents declined far more, by 30-60% (see pages A-126; A-162, ‘National Highway Safety Needs Study, Appendix A’, Research Triangle Institute, March 1976 (DOT-HS-5-01069); Pages 7-2 to 7-8, ‘One-Way Streets and Reversible Lanes’, Synthesis of Safety Research Related to Traffic Control and Roadway Elements, Volume I, Research Triangle Institute, March 1976 (FHWA-TS-82-232), December 1982; Page 28, Dr. Charles Zegeer, University of North Carolina, ‘Pedestrians and Traffic-Control Measures’, National Cooperative Highway Research Program, Synthesis of Practice, #139, November 1988; and Chapter 10, Peter A. Mayer, Chapter 10, ‘One-Way Streets’, Traffic Control and Roadway Elements, Their Relationship to Highway Safety, Highway Users Federation for Safety and Mobility, 1971).

    In 1959, the Oregon State Highway Department published a report which summarized the overall impact of converting two-way state highway sections through town and city centers to one-way couplets along several state highways (Oregon State Highway Department, ‘A Study of One-Way Routings on Urban Highways in Oregon’, Technical Report #59-4, April 1959). In twelve small-size Oregon cities which had made these conversions, the traffic accident rate declined 24% while the pedestrian accident rate declined 38%.

    Regarding pedestrians crossing one-way streets, one leading safety expert noted: ‘”Conversion from two-way to one-way street systems has consistently been found to reduce pedestrian accidents” (Dr. Charles Zegeer, University of North Carolina, ‘Engineering and Physical Measures to Improve Pedestrian Safety’, from 1988 WALK ALERT Program Guide, National Pedestrian Safety Program).


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