Status Report on Traffic Signal Optimization in the Washington Region - PowerPoint PPT Presentation

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Item #12. Status Report on Traffic Signal Optimization in the Washington Region. Edward D. Jones Prince George’s County DPW&T and Chair, Traffic Signals Subcommittee Transportation Planning Board March 18, 2009. Background.

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Status Report on Traffic Signal Optimization in the Washington Region

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Status report on traffic signal optimization in the washington region

Item #12

Status Report onTraffic Signal Optimizationin the Washington Region

Edward D. Jones

Prince George’s County DPW&T

and Chair, Traffic Signals Subcommittee

Transportation Planning Board

March 18, 2009


Background

Background

  • TPB requested a regional traffic signal optimization status report at the January 28 meeting

    • Identified as CLRP priority area

  • Follows from the 2002-2005 signal optimization Transportation Emissions Reduction Measure (TERM)


What does it mean for signals to be optimized

What Does It Mean for Signals to Be Optimized?

  • Traffic signals re-timed for optimal performance, considering

    • traffic loads

    • cross traffic, left and right turns

    • pedestrians

  • Coordination of multiple signals (e.g., downtown areas, corridors)


Optimized does not always mean minimal delay for an individual motorist

Optimized Does Not Always Mean Minimal Delay for an Individual Motorist

  • If there are high traffic volumes / left and right turns / high cross-traffic volumes

  • If you are traveling in the opposite direction of predominant flow

  • Ensuring the safety of and sufficient crossing time for pedestrians


How do we know that signals are optimized

How Do We Know that Signals are Optimized?

  • Engineers do not rely solely on the “raw” computer output

  • Before and after field observations help verify that the optimization process has been successful

  • Ongoing field observations and monitoring from the traffic control center are important, with fine-tuning if necessary

  • These monitoring and spot checks activities, as well as responding to citizen inquiries and complaints, all help ensure the system remains working properly


Survey

Survey

  • TPB staff surveyed transportation agencies by email February and March 2009

  • Survey focused on whether signals were optimized or checked within calendar years 2006-2008

    • Follows the 3-year engineering rule-of-thumb

  • Responses reflect >98% of all signals in the region that are subject to optimization

    • Signals not subject to optimization were not included in the survey (e.g., firehouse emergency signals and pedestrian crosswalk flashers)


Optimization results 2006 2008

Optimization Results (2006-2008)

  • Approximate total signals in region: 5,400

  • Total optimized, checked, or adjusted: 80%

    • Computer optimized: 56%

    • Other check or adjustment: 24%

    • Weighted average (2005 TERM methodology): 68%

  • Not checked: 18%

  • No report: 2%


How is the region doing on optimization compared to 2005

How is the Region Doing on Optimization Compared to 2005?

  • Weighted average of 68% is the same as in 2005

  • However, we are doing better than that may indicate because:

    • The most critical signals in many cases are being checked and optimized even more frequently than once every 3 years

    • All agencies (with >50 signals) reported that they had optimized or checked significant numbers of their signals within the reporting period

    • Anecdotal reports of more resources annually being put into optimization – beneficial if continued


Outlook

Outlook

  • Continuing awareness of and commitment to safe and effective signals operations

  • Effective interagency coordination through the Traffic Signals Subcommittee and other forums

  • The benefits of providing sufficient resources to ensure good signals operations are widely recognized


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