Reopening of Freeway Awaits Tunnel Check

The two-mile section of the Hollywood Freeway that was closed Friday because of the subway tunnel fire will not be opened before this afternnoon, and the closure might last substantially longer, state transportation officials said Friday.

A 100-foot section of the roof over the stricken tunnel collapsed to within 10 feet of the freeway, and officials are concerned that heat from the fire might have weakened the 18- to 20-foot-thick wall of soil directly between the tunnel and the freeway.

Jerry Baxter, head of the state Department of Transportation district encompassing Los Angeles, said the agency would not be able to make any decisions about reopening the freeway until civil engineers were able to enter the tunnel and assess the strength of the soil above it. The fire directly under the freeway was extinguished Friday afternoon, but engineers were driven back by the heat when they attempted to enter the tunnel.

According to Los Angeles Fire Marshal Dave Parsons, engineers were planning to enter the tunnel Friday evening, if it had cooled sufficiently, to begin shoring it up with a timber frame. They hoped yo have the framing completed by this morning.

If the freeway segment remains closed through Monday or longer, it is expected to create problems for commuters because the freeway, U.S. 101, is the main artery linking downtown Los Angeles to Hollywood and the San Fernando Valley.

Engineers reported being concerned about the safety of the freeway because it is not built on bedrock in that area. Rather, it is supported by compacted earth and sand that have been injected with cement-like grouting for bonding. The bonded material is not as strong as either concrete or rock, and engineers feared that the bonding may have been weakened by the intense heat from the flames.

Temperatures inside the tunnel reached about 1,800 degrees Fahrenheit.

Engineers took some of the bonded material--from a section that had not been affected by heat--to a laboratory where they planned to heat it and measure the loss of strength, if any. If that test shows little effect from the heat, Caltrans officials expressed more confidence about reopening the freeway quickly.

Civil engineer Ed Kavazanjian of Earth Technologies Inc. in Los Angeles said that engineers have had little experience with the effects of heat on the grouting, but that “most likely” it would not be damaged by the heat.

But the reopening date will not be determined, experts said, until engineers can get inside and inspect the tunnel.

Once inside, they will be looking for any evidence of settling, which would be an immediate indication that the safety of the freeway is threatened. If no visible evidence of danger appears, they are expected to bore holes into the compacted material to assess its strength and to remove samples for testing.

The freeway itself is almost certainly not damaged, officials said, because of the insulating properties of the soil between it and the tunnel.