Caltrans Begins Preliminary Investigation on I-5 Tunnel Fire

Interstate 5 is open in both directions once again, though traffic southbound will be heavier than usual because of the mix of cars and trucks on the highway. Two transition roads on the Southbound 5 remain closed indefinitely: The one that sends traffic to the Northbound 14, and the southbound truck bypass tunnel. That's where Friday night's deadly crash and fire happened. KPCC's Special Correspondent Kitty Felde has the latest on repairs to the Newhall Pass truck tunnel.

Kitty Felde: The fire department gave the all clear for Caltrans to begin repairs at 6:00 a.m. Sunday. Right away, crews shored up the truck tunnel that runs underneath Interstate 5. That allowed cars to move on the highway above. Caltrans District 7 Director Doug Failing says it's now up to a lab in Texas to examine core samples of concrete taken from inside the tunnel.

Caltrans District 7 Director Doug Failing: There was very high heat, as you've heard reported. There is quite a bit of damage, particularly at the northerly portal, sufficient to where it may well have changed the chemical and strength properties of the concrete and the steel that is supporting the tunnel walls.

Felde: The fire burned as much as 3.5 inches into that concrete. Failing says the steel looks good, but to be sure, engineers have pulled out five samples of the rebar for better analysis. Caltrans has authorized $2.25 million for the shoring and cleanup work. Failing says the actual cost for repair won't be known until Caltrans knows what it has to fix.

Failing: The main question for us is not – "Do we have to replace the entire tunnel?" It's "How deep within the tunnel walls does the damage go, so what do we have to do to repair it?"

Felde: C.C. Myers – the same company that repaired the Santa Monica Freeway collapse after the Northridge Quake in 1994 – has been helping with the cleanup work. As in that job, bonuses will be part of the incentive to get the Interstate 5 repair job done as quickly as possible. But Failing says the work won't shut down the freeway completely.

Failing: When we do construction like this, there may be some temporary closures as you've seen us do in the past – a few hours a night. But at this point in time, our goal is to be able to repair this tunnel and keep traffic flowing.

Felde: Failing says engineering codes haven't changed much since the tunnel was built. But there will be one improvement: The lighting.

Failing: There was 1971 lighting that had been there for a very long period of time. And there had been some problems indicated from what I've been hearing from truckers with that lighting. I haven't seen anything from our maintenance records.

Felde: Lighting did not play a role in Friday night's accident. Lights in the tunnel are turned on only during daylight hours. Truckers rely on their headlights at night. Failing says tunnels are never an engineer's first choice. But he says the Interstate 5/Highway 14 interchange has two challenges: Steep grades, and passenger cars that weave back and forth so they can change freeways.

Failing: All of that is complicated with the fact that Interstate 5 is an exceedingly heavy truck route for us. Trucks have a much more difficult time in changing lanes and handling grades. So at the time this was designed, it was recognized that we're going to need to provide an alternative for trucks to be able to keep them out of the main flow of cars through this particular interchange.

Felde: There have been some reports of trucker complaints about the safety of the tunnel. Doug Failing says Caltrans checked its records for the past three years and found there were 5 accidents – none of them fatal. He described that record as "well below" what could be expected for such a high volume area.