When conditional priority was deployed in Eindhoven, the Netherlands; buses experienced 27 seconds of delay without priority and no significant change in delay under conditional priority.
Date Posted
11/14/2000
Identifier
2000-B00162
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Conditional Bus Priority at Signalized Intersections: Better Service Quality with Less Traffic Disruption

Summary Information

In Eindhoven, the Netherlands (population 300,000) conditional priority was deployed and tested. The test evaluated peak period vehicle delay (for all vehicles) and bus schedule adherence for three different signal priority scenarios over a three day period.

  • No priority – provided no signal priority for transit buses approaching the intersection.
  • Absolute priority – provided a green phase to each bus regardless of whether or not it was running ahead of schedule.
  • Conditional priority – provided priority to a bus only when it was behind schedule.

To measure the impacts on overall traffic delay, video cameras were mounted on four utility poles at the busiest intersection on the bus route (Line 1) and manual observations were made during each priority condition. Traffic delay was defined as the difference between the actual time it took a vehicle to traverse the intersection and the time it took a typical unimpeded vehicle to do the same.

Buses were equipped with onboard computers and wireless communications to track schedule adherence and request priority from approaching signal controllers. Data on schedule deviation, run times, and delay were downloaded each day from the computer to evaluate schedule adherence and bus delay. Bus delay was defined as the time spent standing still or at speeds of less than 5 km/h, excluding time spent at bus stops.

Overall, the results showed that compared to no priority, vehicular delays for all traffic under conditional priority were about the same, while absolute priority caused large increases in delay. Total delay increased by 40 seconds per vehicle during the three busiest hours when buses were given absolute priority, while conditional priority caused very little change in delay.

Bus performance data showed a strong improvement in schedule deviation during periods with conditional priority compared to periods with no priority. During periods with conditional priority, buses were rarely more than 1 minute early or more than 2 minutes late. In contrast, during periods of no priority, the 85th percentile range (band) of arrival times for buses on the route was nearly twice as large. There was no significant change in delay with the buses operating under conditional priority. Buses experienced an average of 27 seconds of delay without priority. This figure dropped to 3 seconds per bus with absolute priority. During conditional priority, the bus delay fell in between these values. 90 percent of all buses received zero-delay service under absolute priority. Only 74 percent of the late buses experienced zero-delay service under conditional priority.

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Deployment Locations