Ramp Meters

What they are, why we have them and what we've learned

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Twin Cities Metro Area Ramp Meter Study

In 2001, MnDOT released the results of an independent study on ramp metering in the Twin Cities metro area. Cambridge Systematics of Cambridge, Mass. evaluated the traffic flow and safety impacts associated with turning off all 430 ramp meters for six weeks as mandated by the 2000 Legislature.

The study began with a five-week pre-study data collection in Sept. 2000 in order for the consultant to compare against the data collected when the ramps would be shut down in Oct. In total, both the "before" and "after" data collection took approximately 12 weeks. Read the May 13, 2002 final report.






ramp meter
Ramp meters in action

Public involvement a key contributor
Throughout the study process, MnDOT sought guidance from two committees; a Citizens Advisory and a Technical Committee, both of which were charged with representing the public and ensuring the credibility and objectivity of the study. Both committees provided policy oversight, technical guidance, expertise and quality control.

Additionally, to measure customer satisfaction, the consultant used a series of focus groups and telephone surveys to talk to 1,540 users of the system. The consultant sought out individual traveler-oriented perspectives regarding ramp meters and ramp meter operations. See FAQs about the study.




Results presented to MnDOT by Cambridge Systematics showed that without ramp meters there was:


Market research data collection results showed a number of changes in attitudes among area travelers that occurred once meters were shut off, including:



Actions taken
In 2002, MnDOT launched its new responsive ramp meter timing system to:


A key aspect of the new system was the addition of automated monitoring of wait times at meters so they can be adjusted as needed by MnDOT's traffic management center computers. The new system provides real-time information about ramp delays and limits wait times based on ramp conditions as well as freeway conditions. Specific system features include: