Leading pedestrian interval standards

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Leading pedestrian interval standards are policies that are applied by municipal transportation departments to prioritize the pedestrian in high-conflict intersections, or intersections where there is a high volume of both pedestrians and adjacent turning traffic. Leading pedestrian intervals (LPIs) prioritize pedestrians by providing them with a walk signal that is at least 3-7 seconds ahead of the signal allowing for adjacent drivers to proceed through the intersection. The amount of time allocated to the leading pedestrian interval varies based on the pedestrian crossing distance and the speed of the average pedestrian in the area. In intersections using a Ieading pedestrian interval, pedestrians get the walk signal before any traffic begins moving allowing pedestrians to begin crossing the street and making them more visible to turning traffic. This improved visibility is thought to reduce collisions between turning cars and pedestrians in treated intersections. Leading pedestrian intervals may also be accompanied by leading bicycle intervals which allow bicycle traffic to be prioritized in the same manner.[1]

CONCEPT


Goals
Examples

A municipality identifies an intersection with above-average counts of pedestrian injuries or fatalities from automobile collisions and determines that this high rate of injury is a result of high volumes of pedestrian traffic mixing with a high volume of turning automobile traffic. This municipality desires to reduce the amount of conflict between pedestrians and automobiles by adjusting the signal timing in the intersection to give pedestrians a leading interval of 3-7 seconds before adjacent automobile traffic is given the green light. After implementing the leading pedestrian interval in this intersection, the jurisdiction notes that the number of collisions between vehicles and pedestrians at the intersection fell by more than 20% over the following year.


Specific Example Many municipalities have adopted leading pedestrian intervals as a potential tool to improve pedestrian safety in intersections. As a specific example, the Comprehensive Pedestrian and Bicycle Program for the Borough of State College Pennsylvania identified areas of concern for pedestrian safety based on an analysis of pedestrian-vehicle crash data. Ten intersections were selected to undergo pedestrian improvements, including leading pedestrian intervals. After conducting a before-after analysis, intersections where a leading pedestrian interval was installed were shown to have nearly 50% reduction in pedestrian-vehicle crashes.

Tradeoffs

The use of a leading pedestrian interval in an intersection specifically prioritizes pedestrian movement over other traffic modes as a result, the following tradeoffs may occur:

  1. May negatively impact emergency vehicle response times by delaying automobile traffic by the amount of time allotted to the pedestrian signal lead.
  2. Use of multiple LPIs in a single corridor may increase congestion by lengthening vehicular travel times for commuters and other drivers.
  3. May divert traffic away from the adjusted intersection and increase traffic on adjacent streets as drivers bypass the treated intersection.
  4. May encourage cyclists to bike in crosswalks or to use leading pedestrian intervals as leading bicycle intervals. *
  5. There may be liability concerns for the municipal transportation department in the event of an accident or collision in the treated intersection.

Note: Some cycling advocates encourage the use of LPIs for cyclists as well as pedestrians and do not see this as a trade-off,

Compatibility Assessment

If answered yes, the following questions indicate superior conditions under which the policy is more likely to be appropriate:

  1. Is there a high volume of pedestrian traffic mixing with a high volume of turning vehicular traffic?
  2. Are there frequent accidents involving pedestrians and turning vehicles?
  3. Does the high volume of vehicular traffic discourage pedestrian traffic?
  4. Is the intersection already signalized?
  5. Are there pedestrian-oriented signals?
  6. Does the municipality already have a protocol for leading pedestrian interval implementation?


Design

The following questions should be considered when determining how to implement this policy:

  1. Will leading pedestrian intervals be implemented in only intersections that are already signalized?
  2. Will other pedestrian improvements be implemented alongside the leading pedestrian intervals?
  3. How long should the leading pedestrian interval be for this intersection?
    1. How long is the current crossing distance for pedestrians?
    2. How quickly does the average pedestrian in this community cross the street?
  4. How does vehicular traffic behave in this intersection? Do vehicles have the ability to turn right on red?
  5. Will the leading pedestrian interval be in effect at all times of day or only in peak traffic periods?
  6. Will the implementation of this leading pedestrian interval comply with all other municipal standards, criteria and guidelines?

ADOPTION


PolicyGraphics
  • For governance level(s): Local.
Adopters

Notable entities who have implemented or adopted this policy include:

STAKEHOLDERS


Supporters
  • Advocates - Pedestrian Safety. Assumption: Implementation of LPIs reduces the likelihood of pedestrian-vehicle crashes.[7]
  • Advocates - Bicycle Safety Assumption: Implementation of an LPI may also increase the likelihood of the implementation of a leading bicycle interval providing cyclists with similar benefits to pedestrians.[8]
  • Constituent Groups - Pedestrians. Assumption: Pedestrians are given priority within intersections resulting in improved visibility.
  • Constituent Groups - Local Residents. Assumption: The reduction in accidents that may result from the implementation of an LPI may contribute to a neighborhood being safer overall and more appealing to residents.
  • Constituent Groups - Seniors. Assumption: LPIs may increase the amount of time allotted to pedestrians for street crossing. For older adults these additional seconds may make for a more comfortable pedestrian experience.
Opponents

REFERENCES


Research
  • Safety Effectiveness of Leading Pedestrian Intervals. Fayish, Aaron and Grank Gross. (2010). Transportation Research Record: Journal of the Transportation Research Board 2198 (2010): 15-22. This paper attempts to evaluate the effects of LPI implementation on pedestrian safety in 10 signalized intersections located in the State College, PA central business district.


Resources
Footnotes
  1. 1.0 1.1 Leading Pedestrian Interval - National Association of City Transportation Officials. (2016). National Association of City Transportation Officials. Retrieved 27 April 2016, from http://nacto.org/publication/urban-street-design-guide/intersection-design-elements/traffic-signals/leading-pedestrian-interval
  2. What is an LPI? A Head Start for Pedestrians. (2010). d.ish. Retrieved 27 April 2016, from https://ddotdish.com/2010/12/01/what-is-an-lpi-a-head-start-for-pedestrians/
  3. NYC DOT - Leading Pedestrian Interval Signals. (2016). Nyc.gov. Retrieved 27 April 2016, from http://www.nyc.gov/html/dot/html/infrastructure/leading-ped-intervals.shtml
  4. Bay Street and Davenport Road Intersection Safety Review. (2016). Toronto.ca. Retrieved 27 April 2016, from http://www.toronto.ca/legdocs/mmis/2015/te/bgrd/backgroundfile-79446.pdf
  5. Pedestrian & Bicycle Information Center. (2016). Pedbikeinfo.org. Retrieved 27 April 2016, from http://www.pedbikeinfo.org/data/library/details.cfm?id=4820
  6. Comprehensive Pedestrian and Bicycle Program State College. (2016). Statecollegepa.us. Retrieved 27 April 2016, from http://www.statecollegepa.us/DocumentCenter/Home/View/1450
  7. Streetfilms | LPI – Leading Pedestrian Interval. (2016). Streetfilms.org. Retrieved 27 April 2016, from http://www.streetfilms.org/lpi-leading-pedestrian-interval/
  8. Let Cyclists Go on LPIs. (They’re Doing it Anyway.). (2015). Brooklyn Spoke. Retrieved 27 April 2016, from https://brooklynspoke.com/2015/09/24/let-cyclists-go-on-lpis-theyre-doing-it-anyway/
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