Evaluating Alternative Operations Strategies to Improve Travel Time ...

SHRP 2 L11: Final Appendices
A survey of traffic management centers in eight cities found that ramp metering reduced the accident rate by 24-50% (2).
• Mobility: A ramp metering study in Salt Lake Valley, Utah showed that with an 8 second metering cycle, mainline peak period
delay decreased by 36 percent, or 54 seconds per vehicle (1).
Freeway volume declined 9% and peak period throughput decreased 14% after ramp meters were experimentally turned off in the
Twin Cities, MN (2).
A study of the integrated freeway ramp metering an adaptive signal control on adjacent routes in Glasgow, Scotland found a 20
percent increase in vehicle throughput on the arterials and a 6 percent increase on freeways (3).
A ramp closure at Gardniner Expressway in Toronto, Canada led to daily travel time savings of 225 vehicle-hours per day (6).
A simulation study on I-4 segment in Orlando revealed a reduction of up to 21% in travel time when Variable Speed Limit (VSL) is
used together with ramp metering systems (13).
Five pilot projects were tested on the A40 motorway in Germany and results showed that congestion decreased more than 50%
during peak periods and traffic incidents at the ramps decreased 40% (25).
Ramp metering in Netherlands has helped regulate the flow on highways and has led to measured speed increaases and allowed
capacity increases of up to 5% (27).
Ramp metering at the Oakland-Bay Bridge toll facility in San Francisco, CA resulted in an overall average travel time decrease of
16.5% and a site specific travel time savings averaging from 2.5 to 3.5 minutes per vehicle (51).
A study regarding the use of ramp meters in North America found that the mainline peak period flows increased 2% to 14.3% due
to on-ramp metering (51).
• Efficiency: The benefit-to-cost ratio of the Minneapolis-St. Paul ramp metering system was found to be 15:1 (1).
The Minneapolis-St. Paul, Minnesota shutdown study found that freeway volumes were 10 percent higher with ramp meters than
they were during the shutdown (1).
A study in Glasgow, Scotland found freeway volumes increased five percent with ramp metering (3).
• Energy/Environment: Ramp metering saved 2% to 55% of the fuel expended at each ramp in a simulation study in Minneapolis-St.
Paul (1).
• Customer Satisfaction: Most drivers believed that traffic conditions worsened when the Minneapolis-St. Paul ramp metering
system was shut down and 80 percent supported reactivation (1).
Fifty-nine (59) percent of survey respondents in Glasgow, Scotland found ramp metering to be a helpful strategy (3).
ADDITIONAL DESCRIPTION AND QUANTITATIVE BENEFITS OF TRAVEL-TIME RELIABILITY STRATEGIES Page F-40