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Wednesday, August 22, 2007 - Page updated at 12:00 AM

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Danny Westneat

Math whiz had I-5's number

Seattle Times staff columnist

It's being hailed as the surprise of the summer that the Interstate 5 gridlockapocalypse didn't happen.

I mean, who'd have guessed you could shut down a third of our most congested freeway and not paralyze the region in epic traffic jams? Oliver Downs, that's who.

The case of the vanishing cars is no mystery to him. In fact he predicted it.

Downs is an English-born math brain who likes to be called "Olly." He lives in Redmond, drawn there by Microsoft. He uses math — quantum tunneling, something called the "nonnegative Boltzmann machine" — to predict the future, be it prices of tickets, behaviors of customers or patterns of traffic.

A few days before the state began what it was calling the most disruptive road project in local history, Downs put out a contrary view.

He forecast no extreme clogs anywhere — not on I-5, nor on alternate routes such as Highway 99 or 599. So far he's been right about that.

Then he crazily suggested that one of our chronically jammed roads, the I-405 S-curves in Renton, would actually be better off than normal. Which it has been.

Downs wasn't dead on. Even his optimistic view was too pessimistic. A stunning 50,000 fewer cars are using northbound I-5 some days. It's slow going in the work zone. But in many places, driving has been smoother than before.

How did Olly know?

The long answer is he's the chief scientist for Kirkland-based Inrix, a Microsoft spinoff with a statistical modeling program that collects traffic data from more than 700,000 cars across the country, covering 50,000 road miles, then blends it with a historical analysis of driver behavior to try to predict future car flows.

The short answer is that this is always what happens.

"We took into account how drivers have reacted in the past to road closures," Downs says.

In 1998, British researchers studied what happened to traffic in more than 100 highway and bridge shutdowns in Europe and the U.S. They found that on average 25 percent of all car trips simply evaporated.

People still went to work. Some commuters drove, some found another way in. Some other trips were just not made.

"Drivers are not stupid," Downs says. "They change schedules. They don't take some trips, or they delay them. The net effect of all these little decisions can be dramatic."

There's that word again. Is it me, or does "little" keep rearing up when the subject is our big problem, transportation?

Seattle's primary transit corridor, the downtown bus tunnel, is closed. Gridlock was predicted. We dodged that by doing a "thousand little things," such as moving bus stops and banning cars from Third Avenue.

Now we have closed part of our largest freeway. Still no gridlock. You drivers made sure of that. You did "fifty thousand little things."

Yet all the plans for what to do next are big. Build big rail lines. Bigger roads. Paid for by the biggest tax increase.

Maybe some answers to our traffic mess are little. So little only the guy who does quantum tunneling can see them.

Danny Westneat's column appears Wednesday and Sunday. Reach him at 206-464-2086 or dwestneat@seattletimes.com.

Copyright © 2007 The Seattle Times Company

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