Evaluating the Impact of Signal Phase and Timing

March 4, 2020

Evaluating the Impact of Signal Phase and Timing SPAT


The Aimsun team recently completed an Innovate UK CCAV project called LAMBDA-V. This one-year feasibility study used human driver data to improve the performance and acceptability of connected and autonomous vehicles (CAVs).

As part of the final LAMBDA-V work package, the Aimsun team developed a proof-of-concept for a Signal Phase and Timing (SPaT) evaluation tool within the Aimsun Next modelling environment. A SPaT file gives the sequence of signal groups that is currently deployed, with the minimum and maximum end times for each state within the signal group. This can be used to set effective red, green and amber times for each phase within a cycle.

Evaluating the Impact of Signal Phase and Timing SPAT


The evaluation tool took SPaT messages from a Birmingham City Council feed and then automated the data into the Aimsun Next model. A text box overlaid the model showing the countdown to a traffic light turning red; this made it easier to see the behaviour of cars that would go through the intersection, versus those that wouldn’t, as time ran out and the lights turned red.

Aimsun presented the wider outputs of the SPaT project and demonstrated the tool to members of the SPATULA committee at a workshop in Q1 2020.

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