I Wonder: What are the rubber cords on roads for?

I Wonder: What are the rubber cords on roads for?

Credit: Mike di Donato/KTVB

These black cords are used to count traffic around Ada County.

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by Don Day KTVB.COM

Bio | Email | Follow: @DonLDay

KTVB.COM

Posted on May 21, 2009 at 9:07 AM

Updated Wednesday, Oct 14 at 2:21 PM

I wonder those rubber cords stretched across local roads are for.Kate M. by e-mail

It's the familiar "bump bump" as your tires pass over the cords stretched out across a local street. Every time you zip over one of those devices, your activities are being counted.

The Ada County Highway District drapes the long rubber hoses over streets all over the county. When your vehicle rolls over the top, a counter attached to the end adds one number to the total.

"ACHD's traffic counts impact decisions on traffic calming efforts, stop sign and signal requests, and are also used in the ultimate planning of what streets may need road or intersection improvements," ACHD spokesperson Robbie Johnson said.

ACHD sets up the counting devices on major roads every two years - and tries to get to other streets every three or four years. Traffic engineers will also do a count requested by residents.

If you are curious how many cars travel down one of your favorite streets on average, you can search the data on the ACHD website .

One more detail: why are there two cords and not just one? It allows traffic engineers to understand how many cars are travelling in each direction. The counter can tell which direction a vehicle is travelling based on which cord the car's tires hit first.

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