Minnesota Study Assessed the Benefits of an Adaptive Signal Control System Using Decentralized Control Depending on Local Traffic Information.
Max-pressure control is a relatively new intersection signal timing technology that uses a decentralized control algorithm depending only on local traffic information and is mathematically proven to achieve maximum throughput for a city road network. Specifically, this technology uses a mathematical model to calculate a pressure (such as waiting time) value for each signal phase, activating the one with the greatest pressure. This study conducted simulation experiments on a calibrated traffic model of seven intersections in twin cities metro area, Hennepin County, Minnesota, by modifying the theory behind max-pressure control to model first-in-first-out behaviors on lanes shared by multiple turning movements, and to force max-pressure control to follow a signal cycle, utilizing intersection data for 2019.
In this study, the researchers modified the existing max-pressure control model by adding the maximum waiting time into the mathematical formulation. They implemented and calibrated microsimulation models with max-pressure controllers for two Hennepin County corridors with seven intersections using signal timing data and 15-minute observed counts, and compared different versions of max-pressure control with existing actuated- coordinated (AC) signals. The maximum cycle length and the time step were varied. For each intersection of a network, results from the existing AC signal control and the different max-pressure controls were compared to evaluate the performance of the
cyclic max-pressure controls, specifically in terms of intersection throughput and lane delays. The economic benefits from congestion mitigation are detailed below.
- The results indicated large reductions in delay, sometimes over 50 percent, comparing AC signal control and max-pressure signal control. These findings indicated that max-pressure signal timing not only achieved higher throughput during peak demand but also demonstrated better responsiveness to queues.
- Specifically, depending on the intersection and the time of day, delay reductions of up to 75 percent (from 32.942 to 8.1455 s), and throughput improvements of up to 16.5 percent (from 1488.65 to 1733.89 vph) were observed when AC and max-pressure signal timings were compared.
- Based on the estimated delay reductions and the Value of travel time savings (VTTS) from the guidance provided by United States Department of Transportation (USDOT) the estimated total travel time savings of the max-pressure adaptive signal control system was $966,464,163 per year, which was greater than its system cost ($69,961,900).