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Freeway Management > Ramp Control > Ramp Metering


Traffic signals on freeway ramp meters alternate between red and green signals to control the flow of vehicles entering the freeway. Metering rates can be altered based on freeway traffic conditions.


Agencies that manage multimodal transportation corridors can use AMS methodology with ICM decision support systems to facilitate predictive, real-time, and scenario-based decision-making.(12/01/2016)

Future ICM systems will require new technical skill sets. Involve management across multiple levels to help agencies understand each other’s needs, capabilities, and priorities.(06/30/2015)

Use Analysis, Modeling, and Simulation (AMS) to identify gaps, determine constraints, and invest in the best combination of Integrated Corridor Management (ICM) strategies.(September 2008)

Follow a modular approach when deploying complex projects in locations with a shortened construction season.(April 2000)

Follow a modular approach when deploying complex projects in locations with a shortened construction season.(April 2000)

In a recurring congestion scenario, ramp metering, variable speed limits, and hard shoulder running found to improve corridor travel time and network performance by 5 to 16 percent. (09/01/2018)

Modeling effort shows Active Transportation Management systems can reduce average morning travel time by 21 percent on the I-270 corridor.(08/01/2018)

Ramp metering and dynamic speed limits shown to reduce congestion and shorten average travel times by about 2.5 minutes on a 7.8 km stretch of the A25 motorway in France.(September 4-6, 2017)

When combined, ramp metering and variable speed limits may reduce conflicts by 16.5 percent and crash odds by 6.0 percent in weaving segments.(January 2017)

Simulation models show that roadside information used to gap-meter mainline traffic near freeway on-ramps can reduce delays related to merging traffic by 17 to 27 percent.(November 16, 2016)

Dynamic ramp metering strategies designed to actively counter developing bottlenecks can reduce vehicle delay up to 48 percent.(06/01/2015)

Ramp metering system improved delay by 25 percent and reduced crashes by 22 percent per ramp meter in Auckland, New Zealand.(10/8/2014)

A multi-modal ICM strategy designed for the I-95/I-395 corridor has potential to increase person throughput 14 to 38 percent.(June 2014)

A multi-modal ICM strategy designed for the I-95/I-395 corridor has potential to reduce average travel times 48 to 58 percent.(June 2014)

A multi-modal ICM strategy designed for the I-95/I-395 corridor has projected benefit-to-cost ratios ranging from 4:1 to 6:1.(June 2014)

A multi-modal ICM solution for the I-95/I-395 corridor would cost approximately $7.45 Million per year.(June 2014)

A multi-modal ICM strategy designed for the I-95/I-395 corridor has potential to reduce fuel consumption 33 to 34 percent.(June 2014)

The implementation of ramp metering in Kansas City increased corridor throughput by as much as 20 percent and improved incident clearance by an average of four minutes, with these benefits remaining consistent in the long term.(April 2013)

The Kansas City Scout program used ramp meters to improve safety on a seven mile section of I-435; before and after data indicated that ramp meters decreased crashes by 64 percent.(2012)

The Kansas City Scout program used ramp meters to improve traffic flow and reduce overall peak period travel times on a seven mile section of I-435 by 1 to 4 percent.(2012)

Active ramp metering on critical freeway segments can reduce travel time variability 24 to 37 percent.(11/03/2011 12:00:00 AM)

Initial findings from a ramp meter evaluation in Kansas City were consistent with findings in other cities that show ramp metering can reduce crashes by 26 to 50 percent.(January 2011)

Initial findings from a ramp meter evaluation in Kansas City show that ramp meters make it easier for drivers to merge and reduce overall travel times.(January 2011)

Customers increased travel speeds by 180 to 220 percent during peak times on Miami-Dade I-95 HOT lanes with significant improvements in travel time reliability.(January 21, 2011)

ICM improves center-to-center communications, traveler information, and traffic management(October 2010)

Integrated Corridor Management (ICM) strategies that promote integration among freeways, arterials, and transit systems can help balance traffic flow and enhance corridor performance; simulation models indicate benefit-to-cost ratios for combined strategies range from 7:1 to 25:1.(2009)

Full ITS deployment in the Seattle area projected to reduce recurrent congestion delays by 3.2 percent and incident related delays by 50 percent.(May 2005)

Full ITS deployment in Seattle projects personal travel time reductions of 3.7 percent for drivers and 24 percent for transit users.(May 2005)

Full deployment of comprehensive ITS strategies in Seattle are projected to reduce CO, HC, and NOx emissions by 16 percent, 17 percent and 21 percent, respectively and reduce fuel consumption by 19 percent.(May 2005)

Full ITS deployment in Seattle projects vehicle speeds to increase by as much as 12 percent on major roadways.(May 2005)

In Salt Lake Valley, Utah a ramp metering study showed that with an 8 second metering cycle, mainline peak period delay decreased by 36 percent, or 54 seconds per vehicle.(March 2004)

In Minneapolis-St.Paul, an evaluation of the effectiveness of ramp meters on four test corridors showed that the number of commuters who supported a complete ramp meter shutdown declined significantly from 21 percent in 2000 to about 14 percent in 2001.(10 May 2002)

In Minneapolis-St.Paul, an evaluation of the effectiveness of ramp meters on four test corridors showed that freeway travel speeds decreased 5 to 10 percent and freeway travel times increased 5 to 10 percent between 2000 and 2001.(10 May 2002)

In Minneapolis-St.Paul, an evaluation of the effectiveness of ramp meters on four test corridors showed that the number of crashes recorded for the interim period with reduced ramp metering capacity was 15 percent higher that the average number of crashes measured for the previous fully metered periods. (10 May 2002)

The CORSIM simulation model has been used to estimate ramp metering speed improvements at the merge influence area under different ramp and mainline volumes, acceleration lane lengths, and number of lanes conditions, and the simulated outputs show that the average speeds at the merge influence areas increase when on-ramp junctions are metered, and that the increase is most prevalent under high traffic volumes, short acceleration lane, and low number of mainline lanes. (13-18 January 2002)

A simulation study in Minneapolis-St. Paul estimated that ramp metering decreased total system travel time by 6 to16 percent and increased average mainline speeds by 13 to 26 percent.( 13-17 January 2002)

A simulation study in Minneapolis-St. Paul estimated that ramp metering saved 2 to 55 percent of the fuel expended at each ramp.( 13-17 January 2002)

Simulations indicated that using a decision support tool to select alternative traffic control plans during non-recurring congestion in the Disney Land area of Anaheim, California could reduce travel time by 2 to 29 percent and decrease stop time by 15 to 56 percent. (December 2001)

A simulation study of existing ITS (traveler information, ramp metering, and DMS) on a Detroit freeway demonstrated how these technologies can increase average vehicle speed, decreased average trip time, and reduce commuter delay by as much as 22 percent.(July 2001)

A simulation study of existing ITS (traveler information, ramp metering, and DMS) on a Detroit freeway demonstrated how these technologies were beneficial to corridor capacity.(July 2001)

Most drivers believed that traffic conditions worsened when the Minneapolis-St. Paul ramp metering system was shut down and 80 percent supported reactivation.(February 2001)

When the ramp metering system on Minneapolis-St. Paul freeways was shut down, speeds fell by seven percent. (February 2001)

When the ramp metering system on Minneapolis-St. Paul freeways was deactivated, crash frequency increased by 26 percent.(February 2001)

Net annual vehicle emissions increased by 1,160 tons and fuel consumption decreased by 5.5 million gallons when the ramp metering system on Minneapolis-St. Paul freeways was shut down.(February 2001)

Volume decreased by 9 percent and peak period throughput was reduced by 14 percent when the ramp metering system on Minneapolis-St. Paul freeways was deactivated.(February 2001)

A study found that the benefit-to-cost ratio of the Minneapolis-St. Paul ramp metering system was 15:1.(February 2001)

Adaptive signal control integrated with freeway ramp meters in Glasgow, Scotland increased vehicle throughput 20 percent on arterials and 6 percent on freeways.(January 2000)

A survey of drivers in Glasgow, Scotland, found that 59 percent of respondents thought that ramp metering was very helpful or fairly helpful.(January 2000)

Adaptive signal control integrated with freeway ramp meters in Glasgow, Scotland improved network travel times by 10 percent.(January 2000)

A six year evaluation of freeway ramp metering in Arizona found that that the system reduced sideswipe accidents on the mainline by smoothing traffic flow, but increased rear-end accidents on entrance ramps where vehicles were required to slow down or stop unexpectedly.(August 1999)

In Glasgow, Scotland a freeway ramp metering system installed at an entrance ramp to the M8 motorway reduced the frequency of early merging by 29 percent.(12-16 October 1998)

In the St. Paul, Minnesota region ramp metering has increased throughput by 30 percent and increased peak period speeds by 60 percent.(November 1997)

The delay reduction benefits of improved incident management in the Greater Houston area saved motorists approximately $8,440,000 annually. (7 February 1997)

A 1995 North American survey of traffic management centers using ramp metering, identified reductions of 15 to 50 percent in freeway crashes.(June 1995)

In Glasglow, Scotland, ITS evaluation reports show that ramp metering can improve freeway capacity by 5 to 13 percent.(1994-1998)

In Long Island, New York, ramp metering and traveler information increased freeway speeds by 13 percent despite an 5 percent increase in vehicle-miles traveled during PM peak periods.(January 1992)

Implementing Integrated Corridor Management (ICM) strategies on the I-15 Corridor in San Diego, California is estimated to cost $1.42 million annualized and a total 10-year life-cycle cost of $12 million.(September 2010)

The total 10-year project cost of implementing Integrated Corridor Management (ICM) strategies on the U.S. 75 Corridor in Dallas, Texas is estimated at $13.6 million with annualized costs of $1.62 million per year.(September 2010)

The Arizona DOT installed a freeway management system to control and monitor traffic on I-10 and I-19 within the City of Tucson for approximately $3.1 million (2009).(02/01/2010)

The Arizona DOT installed a freeway management system to control and monitor traffic on an 7.5-mile section of Loop 101 in the area of Scottsdale/Phoenix for approximately $1.6 million (2009).(01/27/2010)

In Edmonds, Washington, connecting six arterial traffic signals and five CCTV cameras to a central signal system cost $90,000.(June 2009)

In Snohomish County, Washington, interconnecting five traffic signals and three CCTV cameras to a central signal system cost $91,000.(June 2009)

In Kent, Washington, the cost of connecting five arterial traffic signals and five CCTV cameras to a central signal system and another traffic management center was $92,000.(June 2009)

Planning-level studies indicate that an effective combination of ICM strategies can be implemented for $7.5 Million per year (annualized capital and O&M).(September 2008)

The cost of O&M at the Arizona TMC was estimated at $2 million per year.(January 2006)

The annualized life-cycle costs for full ITS deployment and operations in Tucson were estimated at $72.1 million. (May 2005)

A modeling study evaluated the potential deployment of full ITS capabilities in Cincinnati. The annualized life-cycle cost was estimated at $98.2 million.(May 2005)

The annualized life-cycle costs for full ITS deployment and operations in Seattle were estimated at $132.1 million.(May 2005)

TMC central hardware costs can exceed $200,000 if regional communications and system integration are required.(5 August 2004)

The $106 million capital cost for CommuterLink - the Salt Lake City, Utah advanced transportation management system - includes numerous components such as a signal system, ramp metering, traveler information dissemination, traffic surveillance and monitoring, and fiber optic network.(March 2004)

The cost of a freeway ramp metering system in Denver, Colorado was estimated at $50,000 plus the cost of communications.(November 2001)

Minnesota DOT estimated ramp metering operations for FY 2000 were $210,000.(May 2001)

The costs of the Integrated Corridor Management Project (ICTM), deployed on an 8-mile section of the I-494 transportation corridor south of the Twin Cities in Minnesota, was $9 million.(April 2000)

Loop Detector - Capital cost/unit - $2400(06/20/2019)

Piezo Axle Sensor - Capital cost/unit - $2400(06/20/2019)

Loop Detector - Capital cost/unit - $2400(06/20/2019)

Ramp Meter - Capital cost/unit - $30000(2012)

Ramp meter (high estimate) - Capital cost/unit - $100000(November 19, 2010)

Ramp meter (low estimate) - Capital cost/unit - $10000(November 19, 2010)

Freeway Ramp Meter - Capital cost/unit - $30000(2007)

Freeway Connector Meters - Capital cost/unit - $30000(2007)

Ramp Meter Signal and Support Assembly - Capital cost/unit - $12700 - O&M cost/unit - $1196(01/27/2010)

Ramp Meter Signal and Support Assembly - Capital cost/unit - $12700 - O&M cost/unit - $1196(01/27/2010)

Ramp Meter Signal and Support Assembly - Capital cost/unit - $12700 - O&M cost/unit - $1196(01/27/2010)

Ramp Meter Signal and Support Assembly - Capital cost/unit - $12700 - O&M cost/unit - $1196(01/27/2010)

Ramp Meter Signal and Support Assembly - Capital cost/unit - $12700 - O&M cost/unit - $1196(01/27/2010)

Ramp Meter Signal and Support Assembly - Capital cost/unit - $12700 - O&M cost/unit - $1196(01/27/2010)

Loop Dectectors (2) - Capital cost/unit - $11000 - O&M cost/unit - $4500 - Lifetime - 5 years(September 2008)

TMC Software/Integration - Capital cost/unit - $200000 - Lifetime - 5 years(September 2008)

Ramp Meter (Signal, Controller) - Capital cost/unit - $11000 - O&M cost/unit - $4500 - Lifetime - 5 years(September 2008)

Ramp Meter - Capital cost/unit - $12700 - O&M cost/unit - $1196(5 August 2004)

Ramp Meter - Capital cost/unit - $12700 - O&M cost/unit - $1196(5 August 2004)

Detection for Ramp Meter - Capital cost/unit - $6500(5 August 2004)

Ramp Meter - Capital cost/unit - $12700 - O&M cost/unit - $1196(5 August 2004)