Using Archived Data to Measure Operational Benefits of ITS Investments: Ramp Meters. Month XX, 2004 Dr. Robert Bertini. Oregon Department of Transportation. Presentation Outline. Research Objectives What is Ramp Metering? Data Sources and Validation Analysis of Ramp Metering
Oregon Department of Transportation
Demonstrate the use and display of archived data from multiple sources as a tool for evaluation and monitoring of freeway operations.
Evaluate the effectiveness of the ramp metering program in Portland, Oregon
Develop tools to facilitate efficient deployment of ramp metering programs in Portland and other places
In the Portland metro area ODOT currently operates an extensive advanced traffic management system from the TMOC including:
The meters were shut down Minneapolis, Minnesota for eight weeks and a before and after analysis was performed. During the peak periods, freeway mainline throughput declined by an average of 14% with the ramp meters off and travel time increased by more than 25,000 (annualized) hours. In addition, crash frequency increased by 26% while the meters were off.
Inductive Loop Detectors
Closed-Circuit Television Cameras
This study determined that loop detectors in the Portland region report an error code when no vehicles pass over a loop in the 20 second data interval.
This makes it impossible to determine whether an error is indeed an error or just that there were no vehicles passing the loop in that given period.
As a result of this study ODOT has updated the software to distinguish between data errors and zero counts, making future data easier to analyze.
It was also determined that the loops count vehicles with 5 axles as two vehicles.
Probe Vehicles equipped with AVL systems made 6 runs along this corridor.
Picture of Palm
Loop detector data was archived at 20 second intervals for the same period of time.
Traffic data upstream of station 6
The most efficient choice for this section of freeway is to maintain flow below 6000 vph at a speed of 40 mph
Several points were considered when suggesting modifications the hypothetical ramp metering system timing plans:
In response to frequent weekend congestion on the eastbound lanes of Highway 26, ODOT implemented weekend ramp metering along an 11-mile corridor, between Helvetia Road and Skyline Road.
In October 2003 these meters were deactivated for one weekend to evaluate the effectiveness of the weekend metering program.
Ramp Metering led to a better quality of service throughout the corridor
Transportation agencies around the world have experienced success with their ramp metering programs. Some have even seen freeway capacity above 2,000 vph per lane.
Unfortunately, ramp meters are not a cure-all. While they can generate significant improvements in some areas, they cannot eliminate all congestion or every accident.
The true measure of their effectiveness, however, is the continued increase in ramp metering implementations such as those demonstrated in cities such as Portland, Oregon.
Dr. Robert Bertini: [email protected]
The full report is available online at: