"No way ," said Shelley Row of the Institute of Transportation Engineers when I gave her the stunning news.

Yes way, I insisted.

"We never make the movies," said Shelley.

Well, you have now. That’s right: Hollywood has smiled upon the people who design merge lanes and speed bumps, who program traffic lights and plop down roundabouts. In "Mission: Impossible III," Tom Cruise stars as a traffic engineer.

Well, Cruise isn’t really a traffic engineer. He’s Ethan Hunt, a member of the Impossible Mission Force whose cover story is that he’s a traffic engineer.

(And Cruise isn’t really Ethan Hunt. He’s an actor playing Hunt. And Hunt is a secret agent playing a traffic engineer. Got it?)

How do we know Tom/Ethan is a traffic engineer? Because in a party scene early in the movie, some civilian friend asks him, "How’s the Department of Transportation?" And then Tom delivers a moving little monologue about how fascinating traffic is, about how a single motorist tapping on the brakes can slow things for miles behind him.

"Booooooring," says the friend.

As it turns out, Cruise’s character isn’t just posing as a traffic engineer. He’s posing as a Virginia Department of Transportation traffic engineer. There’s a scene where Hunt overturns some boxes in his super-secret HQ and a bunch of VDOT brochures spill out. I felt a little frisson of excitement when I saw that familiar orange-and-blue logo.

"It looks like everybody here will be going to see the movie," said VDOT spokeswoman Joan Morris .

And who can blame them? When else are they going to get to see themselves on the big screen?

Traffic engineers probably fall somewhere below lighthouse keepers, orthodontists and sommeliers in the frequency of their depiction by Hollywood. Who knows how many traffic engineers eagerly plunked down their eight bucks for "Traffic" only to discover it was actually about America’s war on drugs?

And bitter was the realization that neither "Rush Hour" nor "Rush Hour 2" had anything to do with backups on the Dulles Toll Road.

"The only other example that we talked about among ourselves is ’The Italian Job,’ " said Shelley of the traffic engineers association. In the 2003 remake of that 1960s film, Seth Green is a hacker who gets into L.A.’s computerized traffic control system and changes the traffic lights to help a group of thieves pull off a heist.

"His big thing was to turn them all green," said Shelley of the traffic signals. "That wouldn’t work. You’d have to have a progression."

That’s the problem with Hollywood. It never gets the details right. Just ask Randy Dittberner , assistant district traffic engineer for VDOT’s Northern Virginia District.

Cruise "said something like if you tap your brakes on a freeway you can watch the ripple effect go back for 200 miles or something," said Randy, 35. "My wife kind of poked me in the side when she heard that. She’s an engineer too, and she said, ’That’s totally bogus. You’d never notice it after a couple miles.’ "

Something else didn’t quite ring true to Randy, and those were the yawns Cruise got when he talked about traffic. That would never happen in the Washington area. We’re so obsessed with the ebb and flow of our vehicles that we’d be positively giddy to find ourselves in the presence of a real, live traffic engineer.

Said Randy: "Most people say, ’You know, there’s this signal two blocks from my house and I have to wait five minutes to get out.’ It’s kind of like being a doctor, the way [people] say, ’I have this pain in my side.’ They want to talk shop. . . . If that was really what [Cruise’s] cover story was, he’d have a lot of people at that party asking him questions like that, I’m sure."

Randy has been into traffic since he was a kid growing up in Mesa, Ariz. Like a lot of kids, he built elaborate looping constructions out of plastic track for his Hot Wheels cars. Unlike most kids, his always included a "designated traffic control zone": a place on the hearth where all the cars could be neatly lined up.

One more indication that Cruise wouldn’t make much of a traffic engineer: You’ve probably seen the previews where he has to dodge explosions on the Chesapeake Bay Bridge-Tunnel while vehicles are jammed up all around him. That would never happen to a real traffic engineer.

"It was a traffic problem that got him all stuck, and he wasn’t able to get out," said Randy. "I thought that was ironic."