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Driving Me Crazy: Freeway on-ramp meters

KGW spoke with drivers who said they are skeptical about on-ramp meters that only let one car at a time onto the highway. Studies have show the red lights do help.

PORTLAND, Ore. — Red lights at freeway on-ramps that only let one car at a time onto highways may be counterintuitive, but they do serve a purpose.

“...Ramp meters make sure traffic gets on the highway smoothly, and in an orderly sequence," said Don Hamilton with the Oregon Department of Transportation (ODOT). "...And that improves the operation of the highway itself.

There are about 150 of these ramp meters across the Portland metro area that regulate the flow of vehicles onto the freeway to help delay the inevitable daily traffic jam at rush hour.

RELATED: Driving Me Crazy: The zipper merge and how it's really supposed to work

A network of sensors, wire loops sealed into the road surface, across the freeway system measure traffic flow. Computers crunch the numbers, performing thousands of calculations a second to help inform the various meters when to turn on, and at what intervals to allow vehicles onto the highway.  

A graphic below from the Federal Highway Administration shows typical placement of a ramp meter, and the measuring sensors on the freeway.

Credit: FEDERAL HIGHWAY ADMINISTRATION

They've been in use in some parts of the U.S. since the 1960s and studies show they do help. In Portland and Seattle, the use of ramp meters has shown positive impacts on travel times and reduced accidents.

Credit: Federal Highway Administration

In Minneapolis and Denver, ramp meters have been shown to reduce emissions as well. 

More about ramp meters from the Federal highway Administration can be found here

Credit: Federal Transportation Administration

In a 2000 study in Minneapolis — the annual cost benefit accounting for things like travel time reliability, fuel consumption, and crash reduction — came out to more than $40 million. 

ODOT just installed a new ramp meter in Wilsonville on the Interstate 5 Southbound on-ramp at Elligsen Road. It has not yet been activated. More details about that specific project can be found here.

I do the Driving Me Crazy feature as a generally -- but not always -- lighthearted take on things that drive people nuts on area roadways. Most of us can relate, and most of these topics are your ideas. What drives you crazy? Post your videos and pictures on my Facebook page. On Twitter. Or if you're just anti-social you can email me cmcginness@kgw.com

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