It’s Time for a Fresh Look at Red Line Subway Plan : MTA brings in top soil and geology experts for reassessment

Mayor Richard Riordan can’t be dismissed as some overzealous critic of the Metropolitan Transportation Authority. As proof, one need look no further than his assertive and successful lobbying of Gov. Pete Wilson for a veto of a bill that would have siphoned off $375 million in tax funds from the MTA over five years.

That gives added weight to the following: “There is no doubt that the MTA has become a justifiably easy target. The moves in Sacramento underscore the need to get the MTA house in order,” Riordan said after Wilson’s veto.

But there is arguably an even more important reason to listen to the mayor these days about transportation issues. That came last Monday, when he backed the hiring of three international leaders in the field of soil and geological conditions--at a cost of $1,200 each, per day, for the next several months. Riordan said that their work should help to determine whether Los Angeles-area conditions are “inconsistent” with an underground subway route.

It is also time for a fresh look, a reconsideration, of the subway plans that we ourselves have endorsed over the years.

You know the route that has caused the most concern. It is the $5.8-billion, 22-mile project that has become one of the costliest public works projects in U.S. history. We refer to the Red Line, which, as planned, will burrow beneath a mountain range to connect Hollywood with North Hollywood. From there, it is to continue westward in the San Fernando Valley to the San Diego Freeway.

You’ve heard about the problems: over budget, behind schedule, months-long construction delays, tunnel walls built thinner than designed, misaligned tunnels, substandard support wedges, subsidence, a sinkhole, flooding, a federal raid on the offices of the tunneling contractor, the contractor’s subsequent firing, and more.

And you’ve heard the frequent refrain of MTA excuses: Unforeseen setbacks are to be expected in a project of such scope; we’ve had problems no worse than any other major transportation project; it doesn’t really matter that the tunnel walls aren’t as thick as designed; trust us, we know what we are doing.

Well, we’re going to need a lot more than that.

A Times news analysis found that Los Angeles is indeed having an unusual amount of trouble for such a project. And while references to the huge problems encountered with the English Channel tunnel and Denmark’s twin waterway tunnels make for interesting reading, they do not matter a whit here. Our particular soil and geologic conditions may very well be unique.

The same “young alluvium” or soft sediment--loose and sandy--soil that has contributed to sinkage and subsidence in tunnel digging may have other repercussions as well. Such soil also slows down earthquake shock waves, increasing their amplitude or energy. In basins like the San Fernando Valley, surrounding mountains trap those waves, causing them to bounce around for longer periods, greatly enhancing quake damage.

Moreover, the subway digging began here (1986) one year before it was proven that hidden thrust faults could cause temblors such as the 1994 Northridge quake. According to some experts, a “shattered glass” pattern of such faults underlies Los Angeles, and we don’t know where they all are.

Such faults also cause strong vertical accelerations, measurable in gravitational forces. One “g” of force can make an unsecured building hop off its foundation. Northridge quake forces measured up to 2g.

The Northridge temblor was caused by a fault that previously was known to only a few petroleum geologists. Such information is exactly what needs to be considered now in taking a fresh look at the MTA’s subway plans. We just wonder why soil and geology experts weren’t looking more closely at these issues much sooner.