SEATTLE — Depending on where you drive, and what time you leave, travel times can be extensive.
Electronic boards above the freeways give you some idea how long the drive will take.
But how accurate are they?
KIRO 7 Traffic Anchor Rachel Calderon spoke with the Washington State Department of Transportation about why drive time predictions aren't always perfect.
Drive times are calculated by WSDOT using loop detectors embedded in roads.
The devices collect data to calculate speed, density and vehicle volumes.
That data is sent back to WSDOT's headquarters and put on its website.
WSDOT engineer Tim McCall says despite the calculations, recent road work or an incident on the highway can throw off the data.
“The public should take the information a little bit lightly, as they are estimates based on current traffic conditions,” McCall says.
One area that's tough to calculate is about a 10-mile stretch in Tacoma on I-5 to Federal Way.
McCall says there's a lot of congestion in the right lane as traffic heads to Highway 18, but WSDOT looks at all lanes of I-5 to calculate drive times.