Answer Man: Highway Lights and Landings

Answer Man's column last week about Dwight Eisenhower and the U.S. interstate highway system brought in two more questions from curious, transportation-minded readers:

I read somewhere that part of the Eisenhower plan included a stipulation that there had to be a straight stretch of road with no bridges or other obstructions every so many miles, to be used as emergency landing strips for aircraft. Any truth to that?

Robert H. Haslinger, Gaithersburg

"False."

So says Richard F. Weingroff, a writer at the Federal Highway Administration and a student of the agency's history. It's an urban legend, one so prevalent that Richard posted a story on the Highway Administration Web site titled "One Mile in Five: Debunking the Myth."

Like the best urban legends, there's a grain of truth to it. Well, not a grain, exactly. And not truth, either. It's more like something that might have been.

You will recall that Germany's autobahn was one inspiration for our interstates. The designers of the autobahn built it with aircraft in mind, and parts of it actually were used as runways.

This dual-purpose ability interested the U.S. Air Force, which, when the plans for our interstate system were being drawn up in the 1950s, put in a request: that every 50 miles or so the highways have a straight three-mile stretch oriented in line with prevailing winds.

"This was to be highly classified, of course," recalled Frank Turner, who spent his entire career with the Highway Administration and rose to lead it under Richard Nixon. "But this was one of the concepts that was cranked into it at that time." (Turner described the plan in a 1988 oral history for the American Association of State Highway and Transportation Officials.)

The agency went so far as to dispatch a team to Europe to study the notion. In the end, it was decided that though it was technically possible to do what the Air Force asked, a combination highway-runway wasn't really a good idea.

"It had to be one or the other," Turner said. (One problem: Even if the interstates were cleared of civilian traffic during wartime, Army convoys would be butting up against Air Force aircraft.)

"It's not totally ludicrous," Richard said of the persistent belief that I-95, I-270 and their brethren are secret airstrips. "It just isn't correct. Most people, if they get on an interstate and drive 10 miles, they would notice there is no mile that's straight."

That's done on purpose, to keep drivers from getting drowsy. Said Richard: "Interstates tend to curve around, even if they don't really have to, as a way of keeping you interested and alert to the driving task."

So, the interstates were not built to be used as runways. However, there's another reason people might be confused, and that's because of something that was built.

During World War II, a network of runways was constructed near major roads. Called "flight strips," they were for emergency use only. Planes weren't equipped with radar and other modern navigational aids then, said Richard, "so a pilot might very well follow a road to get from Point A to Point B."

The flight strips varied in length, smaller ones for lighter aircraft, larger ones for such heavy bombers as B-17s and B-24s. They were near public highways, and each was equipped with a shelter and a telephone, some tools and some fuel.

"During the war, we kept these secret," Richard said. "You could see it if you were driving on the road, but we didn't publish a list of them."

Richard speculates that most of those emergency flight strips are long gone, subsumed by today's sprawl.

Every now and then, you do hear about an airplane landing on an interstate. On the morning of Jan. 13, 1994, a Cessna 172 developed engine trouble over Baltimore. Pilot Clinton Renfrow took the plane higher so he could look for a place to land -- and to buy time in case he needed to glide down.

Which is exactly what he did when his engine conked out. Clinton set the plane down on I-795, rolling under an overpass and coming to a stop.

He was unharmed, and so were his passengers: two radio station traffic reporters who that morning contributed to the sort of traffic jam they usually warned motorists about.

One of the best trivia questions going around is, "Where are the only traffic lights on the interstate highway system?" For a long time, I thought the only ones were on the Woodrow Wilson Bridge, to stop traffic for the draw span, but I was told there are traffic lights on an interstate in Portland, Ore. Can you confirm that?

Stu Newman, Bowie

Interstate 5 between Portland and Vancouver, Wash., has a lift bridge over the Columbia River (or, as Federal Highway Administration spokesman Doug Hecox reminded Answer Man, the "majestic" Columbia River). It's actually two bridges side by side that go by the accurate but somehow soulless name of the Interstate Bridges.

Neither the Interstate Bridges nor the Woodrow Wilson Bridge has what transportation folks consider a traffic light: a light that cycles through at regular intervals, as at an intersection. Rather, they're warning lights that let drivers know when the bridge in question is about to be raised.

When that happens, you want to stop.

Julia Feldmeier helped research this column. Do questions always nag at you? Perhaps I can help. Write answerman@washpost.com, or 1150 15th St. NW, Washington, D.C. 20071.