This is a recording of a talk I gave at the University of Minnesota back in the early 2000s about Ramp Meters on Trial. Ramp meters were controversial when I first arrived in Minnesota, as the delays on ramps were uncapped, so people might wait 10 or even 20 minutes before being allowed onto the freeway. This led to a ramp meter shutdown in 2000, which was a great “natural” experiment. [Link]

Our research on the topic includes:

• Zhang, Lei and David Levinson (2010). Ramp Metering and Freeway Bottleneck Capacity. Transportation Research part A 44(4) 218-235. [doi]
• Levinson, David, Kathleen Harder, John Bloomfield, Kathy Carlson (2006) Waiting Tolerance: Ramp Delay vs. Freeway Congestion. Transportation Research part F 9(1) 1-13. [doi]
• Levinson, David and Lei Zhang (2006) Ramp Meters on Trial: Evidence from the Twin Cities Metering Holiday. Transportation Research part A 40(10) 810-828. [doi]
• Zhang, Lei and David Levinson (2005) Balancing Efficiency and Equity of Ramp Meters. ASCE Journal of Transportation Engineering 131(6) 477-481. [doi]
• Levinson, David and Lei Zhang (2004) Evaluating Effectiveness of Ramp Meters: Evidence for the Twin Cities Ramp Meter Shut-off. (145-166) in Assessing the Benefits and Costs of Intelligent Transportation Systems (ed. David Gillen and David Levinson) Kluwer Publishers.
• Zhang, Lei and David Levinson (2004b) Optimal Freeway Ramp Control without Origin-Destination Information. Transportation Research part B 38(10) 869-887. [doi]