A rising toll lifts all chassis — at least for a little while.

One of the selling points of express toll lanes is that general purpose lanes also will benefit from a quicker commute.

Single drivers and others are enticed to pay a toll to go faster, which in turn frees up space in the “free” lanes. Maybe it’s not 60 mph, but it’s better.

“That is one of the great benefits of doing this kind of traffic management,” said Patty Rubstello, director of toll operations for the Washington State Department of Transportation. “Really all the lanes benefit.”

Let the shiny Lexus fork over the cash. My mildewed Corolla still gets to work faster. In some cases, it proves true — including in our own state.

The HOT commute

Those who travel Highway 167 south of Renton have seen improved commutes since tolling started there in 2008.

By 2012, afternoon rush hour traffic in the general purpose lanes was going 14 mph faster, at an average 56 mph. The morning commute also saw improvement, by 7 mph, to 51 mph. High-occupancy toll (HOT) lane travel maintained at 60 mph and above, just like the high-occupancy vehicle (HOV) lane that it replaced.

That gets some folks excited for the possibilities this fall when similar toll lanes come to I-405 between Lynnwood and Bellevue.

“We do expect to see that on 405 as well,” Rubstello said.

But that was 2012. These days, thanks to an improved economy, that general purpose lane performance has dipped.

The morning commute took 19 minutes in 2012. In 2014, it took 21 minutes.

And stretches of 167 where pre-toll traffic was already moving relatively quicker saw less of an improvement, in one case just 1 mph faster in 2014 compared to 2007.

Not the point

Despite being in our own state, Highway 167 actually isn’t the best predictor of what will happen when tolling starts on I-405. Commute speeds were already above 40 mph before HOT lanes. And there was space to sell in the HOV lane.

A look around the country reflects more of a flash-then-fade kind of improvement in the toll-free commute — if it’s any better at all. Those that saw major improvements to the commute did a lot more than add tolls.

I’ll have more on that next week.

For now, it’s worth a reminder that the goal of express toll lanes is a quick and predictable commute for drivers in the toll lane, not those they pass in the general purpose lanes.

Express toll lanes have risen in popularity because, in a world of tight state budgets and falling gas tax revenues, they’re a way to add capacity without pricey infrastructure projects. Typically, it’s simply working with existing high-occupancy vehicle lanes.

“So you can’t expect a huge change,” said Mark Burris, a research engineer with Texas A&M Transportation Institute. “They’re giving some people a better trip — and hopefully no one worse off.”

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