A transit signal priority system in Eastleigh, England reduced bus fuel consumption by 19 percent and reduced bus emissions by 15 to 30 percent, and increased fuel consumption for other vehicles by 5 percent and increased the emissions of other vehicles up to 11 percent.


Summary Information

This project evaluated the impacts of a transit signal priority system in Eastleigh, England. The system consisted of 25 buses equipped with electronic transponder tags designed to communicate with in-pavement loop detectors installed on eight links at four congested intersections. When a bus was detected approaching an intersection, signal priority control software was activated at the signal controller. A new green phase or green phase extension was granted depending on a pre-defined set of signal control parameters that gave buses high priority over other traffic.

The systems were installed at the following four intersections.
  • Leigh Road/Woodside Avenue / Passfield Avenue (controlled by Split Cycle Offset Optimization Techniques (SCOOT) software).
  • Leigh Road/Romsey Road (controlled by SCOOT software).
  • Romsey Road/Upper market Street (controlled by SCOOT software).
  • Leigh Road/Bournemouth Road (controlled using vehicle-actuation).

At the SCOOT controlled intersections, field data were collected for one week with the system "on" and one week with the system "off." At the Vehicle-Actuated controlled intersection, data were collected for three days with the system "on" and three days with the system "off." Data were collected between 7:30am and 6:00pm each day.

The study area was saturated and transit volumes were maintained at about 4 to 5 vehicle per hour. Roadside and on-bus surveyors measured bus journey times by recording the time of day a bus passed an intersection detector or stop line. Bus journey times “with” and “without” the system activated were used to evaluate system impacts on bus speeds, traffic delays, and system operations. Impacts on bus emission levels and fuel consumption were calculated using speed-related emissions factors derived from a national emissions database. Impacts on other traffic were assessed using general traffic data collected from loop detectors at each SCOOT intersection.


The relatively high priority given to buses improved bus performance and reduced bus delay, bus fuel consumption, and bus emissions; however, because such a high level of priority was granted, additional delays were incurred by other vehicles which resulted in an overall increase in fuel consumption and emissions for all listed pollutants except, Nitrogen oxides (NOx), and particulate matter (PM).

The Transport Research Laboratory (TRL) authors noted that the reductions in NOx and PM were important since these compounds were more likely to exceed acceptable levels in urban environments.



Other Traffic


CO emissions




CO2 emissions




HC emissions




S emissions

-19 %



NOx emissions




PM emissions




Fuel consumption




(Data excerpted from: TRL 411, Table 16 - Summary of Impacts)

See Also:

Monitoring and evaluation of a public transport priority scheme in Southampton, TRL 413.

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Monitoring and evaluation of a public transport priority scheme in Eastleigh

Published By: Transport Research Laboratory

Prepared by the Southampton University and the University of Portsmouth Transport Research Laboratory for the Hampshire County Council

Source Date: 1999

Other Reference Number: Report No. TRL411


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Typical Deployment Locations

Metropolitan Areas


bus priority, traffic signals, TSP

Benefit ID: 2005-00287