Ramp Meters Coming Soon to I-5 in Olympia, Lacey

Submitted by Doug Adamson for the Washington State Department of Transportation

Every afternoon, travelers in Lacey and Olympia sit in backups on southbound I-5, and wonder, why can’t someone fix this? There is some good news. We are.

One way to help maintain traffic flow is regulating vehicles entering the highway. And that’s where traffic meters come in, and what’s coming to Thurston County. Come mid-April, we expect to activate new meters at:

  • Martin Way East
  • Sleater-Kinney Road Southeast
  • Pacific Avenue Southeast
  • Henderson Boulevard Southeast

Ramp meters are an affective and proven tool that help delay the onset of backups seen regularly on southbound I-5 between Lacey and Olympia. They also help reduce the potential for collisions.

What’s causing the backups?
Every day, we see large groups of vehicles flood southbound I-5 at the same time. Drivers naturally slow down due to merging traffic and congestion builds until traffic slows to a crawl.

Ramp meters – traffic signals at the end of highway on-ramps – regulate the flow of traffic entering the highway. The regulated pace vehicles enter the highway makes it more predicable for travelers already using I-5. Meters provide consistent gaps between vehicles, rather than allowing multiple vehicles to flood the highway at once.

But why not add more lanes to I-5? The answer is cost. We look at lower-cost enhancements, such as ramp meters, before big-ticket items like widening I-5. Right now, there is no funding to widen this section of I-5.

Why ramp meters?
Ramp meters are a long-used tool to help improve the flow of traffic on state highways. While new to southbound I-5 in Olympia and Lacey, ramp meters have successfully operated at the Marvin Road and Nisqually on-ramps to northbound I-5 in Thurston County for years.

Another southbound I-5 ramp meter at Marvin Road will activate later as part of the diverging diamond interchange project.

How and when ramp meters work
Ramp meters react to real-time conditions. Using computer-assisted technology and specially trained operators, ramp meters can activate anytime or any day if the network detects I-5 congestion.

On-ramp delays?
While ramp metering benefits the interstate, it can produce delays for drivers merging onto the highway. We will monitor the system and make adjustments as needed. At the same time, we do anticipate it will take longer to reach the highway. We expect some drivers will opt for in-city travel instead of using I-5. And as always, for those able to do so we encourage people to consider alternate forms of transportation such as transitbicycling or walking.

What about northbound I-5?
It’s a worst-first strategy. While there is northbound congestion, southbound is the focus due to longer-lasting afternoon chronic congestion. There also is no funding at this time for northbound ramp meters. However, you can expect this tool for northbound I-5 in the south sound when funding becomes available.

Not stopping in Lacey or Olympia?
Travelers heading to locations south of Olympia can help. Through traffic is encouraged to use the left two lanes. This does not apply to vehicles towing a trailer or vehicle or combination over 10,000 gross vehicle weight.

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