Evaluation of the two self-optimising traffic signal systems Utopia/Spot and ImFlow, and comparison with existing signal control in Stockholm, Sweden

The city of Stockholm has adopted the “Urban mobility strategy” stating that the more surface efficient modes public transport (PT), cycling and walk should be prioritised over cars. This has led to an interest to extend the signal priority for PT beyond its present level. Self-optimising signal control systems can keep the impacts on other traffic at a controlled level when introducing extensive PT priority, and they may reduce the cycle time causing less waiting time for pedestrians and cyclists. In this paper two self-optimising systems are tested and compared with each other and with the existing signal control using microscopic simulation. VISSIM was connected to PC versions of the self-optimising systems Utopia/Spot and ImFlow and to signal controller simulators including PRIBUSS. Both self-optimising systems reduced the average delay per person compared to existing signal control. ImFlow performed better than Utopia/Spot in the evaluation.