Inside Seven
Current Issue: September 2014

by  Maria Raptis
Issue Date: 04/2008

SWARM, an Adaptive Metering System, Premiers in the San Gabriel Valley. UP AHEAD: Congestion Relief and Improved Traffic Flow.

Last month, Caltrans District 7 activated four freeway-to-freeway connector meters from both the northbound Orange Freeway (State Route 57) and the northbound San Gabriel River Freeway (I-605) to the eastbound and westbound Foothill Freeway (I-210) interchanges within the cities of San Dimas to Irwindale in the San Gabriel Valley.

On March 10, the meters to the westbound I-210 were activated for the morning commute and the eastbound meters were turned on for the afternoon commute on March 24.

The project, just one part of congestion relief on this 50-mile I-210 corridor, will by this fall, meter all on-ramps and connectors in both directions from the San Bernardino County line to the Golden State Freeway (I-5). Four freeway-to-freeway connector meters onto eastbound and westbound I-210 will be activated at northbound Glendale Freeway (SR-2) and eastbound Ronald Reagan Freeway (SR-118).  Another meter will be activated at eastbound Ventura Freeway (SR-134) to westbound I-210. Construction for the metering project is now more than halfway complete and operational.

“While District 7 has utilized freeway connector metering for 19 years, a congestion relief project of this scope on a 50-mile corridor is the first such operation in the District and first in the nation,” according to Doug Failing, District 7 Director. 

To allow motorists to acclimate to the signals, the meters were initially set for a “green-ball only” status for two weeks beginning February 25 for the westbound connector and March 6 for the eastbound connector.  Following these adjustment periods, metering was set to full operation mode of red, yellow and green lights, alerting motorists to a complete stop for approximately six seconds.  Prior to reaching the meters, motorists are warned to reduce speed by two flashing beacon signs with these messages:  “Route 210 Meter On” and “Prepare to Stop.”

SWARM, or System Wide Adaptive Ramp Metering, is an algorithm program that allows automatic adjustment to on-ramp meters and freeway-to-freeway connector meters based on real-time situations and traffic flow. SWARM, whose software and hardware were conceptualized by District 7 Freeway Operations Ramp Metering Unit, can calculate historical data from the past few minutes, days, weeks, months or longer, to predict future traffic patterns.

Freeway-to-freeway connector metering is one strategy in the congestion relief effort, which is a part of Governor Schwarzenegger’s Strategic Growth Plan. Connector metering will improve mainline freeway traffic flow, decrease freeway congestion and motorists will see an overall improvement in travel speeds and times.

With SWARM and by monitoring all on-ramp and connector metering on the same corridor, Caltrans expects to significantly reduce bottleneck congestion points and control the overflow of vehicles resulting from freeway demand exceeding freeway capacity. The meters adapt and re-adjust to control congestion or to help motorists get through incidents better and control too many vehicles entering the I-210 simultaneously.

The I-210 Congestion Relief Project received much attention last month from the public and media asking for the Department’s perspective on the concept and how the project is progressing. Frank Quon, Deputy District Director, Operations, said, "In these first weeks of operation, more frequent free-flow traffic occurred during the morning commute than in the past. Caltrans realizes that we have changed the operation from what motorists have been used to for many years.”

Metering also helps alleviate "platooning" or constant streams of vehicle flow that makes accessing the freeway difficult for motorists entering at on-ramps.  The congestion relief plan will also help with unnecessary 'weaving" that occurs with quick, last-minute maneuvers by motorists’ attempts to get on and off the freeway amongst a steady stream of traffic flow.

According to Marco Ruano, Chief, Freeway Operations, “The key is to give this change enough time for traffic patterns to adjust. We will have a complete picture once the adaptive metering plan is in full operation at five additional connectors and when all on-ramp meters are operating along the entire corridor."

Interstate 210 Project Map