RITA | ITS | Benefits: Conditional transit signal priority helps buses arrive on time and minimizes impact on other traffic.

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ITS >> Benefits Database >> Conditional transit signal priority helps buses arrive on time and minimizes impact on other traffic.

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Conditional transit signal priority helps buses arrive on time and minimizes impact on other traffic.

In Eindhoven, the Netherlands, 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 treatments over a three day period.

No priority – 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.

RESULTS

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, schedule adherence was nearly twice as varied.

See the related ITS Benefits Database entry for more information.

Past "Benefit of the Month" summaries are also available.

Last Modified: 06/01/2006

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