In KIRO Radio’s Chokepoints series, we take a closer look at the traffic issues plaguing commuters in the Puget Sound region.

The tolls on the Tacoma Narrows Bridge were set to pay back the bonds used to build the bridge. We will be paying tolls on the bridge until about 2037, 30 years after the bridge opened.

But KIRO Radio listener Dave Thomas asked why the price of the toll on the Tacoma Narrows Bridge doesn’t fluctuate with traffic, as it does on the 520 bridge or in the 167 HOT lanes.

According to the Washington State Transportation Commission and the tolling division of the Department of Transportation, tolls are not being used on the Narrows to control congestion or manage traffic. That’s why they don’t vary.

Variable tolls are used to control congestion and the state said there is enough capacity on the Narrows to handle all the current traffic.

That means variable pricing isn’t necessary.

The tolls on the 520 bridge were created to pay back the bonds and manage traffic, which is why they are variable.

The HOT lane tolls are entirely about managing traffic, which is why they are variable.

The Transportation Commission says it’s possible that the Narrows could be converted to variable tolling, but only if it was necessary.