Synergies of Combining Demand- and Supply-Side Measures to Manage Congested Streets

Research Team: Michael Cassidy (lead), Carlos Daganzo, and Ibrahim Itani

UC Campus(es): UC Berkeley

Problem Statement: Congestion pricing has been used in cities to limit flows into congested neighborhoods. Pricing does not necessarily reorganize how flows are served, however. Since organizational inefficiencies tend to arise naturally in congested traffic, combatting this type of congestion by means of pricing alone may require high tolls. This can be quite regressive. Complementary strategies to reorganize flows could help reduce the tolls required to alleviate congestion. The challenge lies in choosing organizing strategies that both diminish workload on a network by diminishing vehicle miles traveled (VMT); and enhance network productivity by reducing vehicle hours traveled (VHT).

Project Description: The research will explore the optimal banning of vehicular left‐turn maneuvers at certain signalized intersections in a city as a traffic reorganization strategy. The prohibitions would be imposed only on those intersections that reside inside select zones within the larger city, and only at select times of day. This study developed agent-based simulations of traffic flow in an urban network resembling downtown Los Angeles to explore synergies when congestion pricing and left-turn prohibitions are jointly deployed.Traffic was simulated for different scenarios representing a morning commute, each with a fixed number of travelers and a given traffic management strategy. In each simulation, travelers choose when to depart their homes in order to minimize the combination of unpunctuality at work and in-vehicle delay due to congestion. Our performance metric was the sum of these two costs across all travelers.

Status: Completed

Budget: $79,630

Project Partner(s): Caltrans

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