A tunnel runs through it

IMAGINE A TUNNEL SO LONG you can’t see any light at the end of it. Now imagine that same tunnel jammed with automobile traffic, perhaps caused by an accident. No one’s moving; drivers are trapped underground for who knows how long, and there is no escape.

This might sound like a punishment for sinful claustrophobes straight out of Dante’s Inferno, but it could actually happen in some higher elevations if some transit decision-makers get their way. There are three proposals under study in Southern California for tunnels far longer than any others in the United States.

Creative thinking about the region’s vexing traffic problems is always welcome. But mega-tunnels have so many serious drawbacks that they should only be considered as a last resort. The main reason they are being taken seriously is money. Tunneling technology has improved to make building these gargantuan gopher holes much cheaper; meanwhile, the price of urban real estate has risen steeply, increasing land-acquisition costs for surface freeways.

That doesn’t mean tunneling is cheap. According to a recent Times article, underground freeways can be two to three times more expensive per mile than a surface route. And tunnel projects tend to hit unexpected snags, ratcheting up the cost -- as any examination of the huge cost overruns on L.A.’s subway system will show. Other objections to tunnels center on safety and practicality. Geologists don’t begin to understand the network of faults crisscrossing the San Gabriel Mountains; digging long tunnels through them, as one proposal for a 23-mile complex of tunnels and surface highways from Palmdale to Glendale would do, is a scary prospect. Underground aquifers in the mountains also could crack tunnel walls. And accidents in mega-tunnels can be deadly. Thirty-nine people died in 1999 after a truck caught fire in the seven-mile Mont Blanc tunnel between France and Italy.

But the main objection to tunnels is more philosophical. It’s a truism in Southern California: If you build it, they will drive on it. New freeways (or expanded old ones) tend to lure more people into their cars, and the new routes quickly become just as jammed as the old ones. There is no reason to think the same thing won’t happen with underground freeways. Building tunnels does nothing to get people out of their cars, a necessity if the nation wants to reduce its reliance on oil and Southern California wants cleaner air and less traffic. If taxpayers are going to pay the cost of building miles-long tunnels, it would be wiser to put trains in them than automobiles.

That said, some tunnel projects make more sense than others. One of the ideas under study, a five-mile tunnel under South Pasadena and Pasadena linking the Long Beach and Foothill freeways, may be the only option left for making the connection, a vital link that has been stalled for 50 years by residents in the surface route’s path. The other two -- the Palmdale-Glendale link and a proposed 12-mile tunnel under the Cleveland National Forest, connecting Cajalco Road in Riverside County with the Laguna Freeway in Orange County -- are visionary but flawed concepts. Both address serious traffic problems, but there are better ways to solve them.