A busy Los Angeles freeway tunnel section reopened January 10 after it was ravaged by fire six months ago when a tanker truck carrying 8,500 gallons of fuel overturned and burst into flames. The July 13 accident occurred where the northbound 2 Freeway meets the northbound I-5.
The fire caused extensive damage to the walls and ceiling of 400-ft-long tunnel, as well as to outrigger beams, support columns, and about 800 ft of roadway through the tunnel. While the flames didn't exactly melt the concrete, they did cause it to spall and delaminate between two and four inches below the surface.
After a $5 million emergency quick-fix of falsework and stabilization by C.A. Rasmussen of Valencia, CA, the tunnel section was closed by Caltrans for testing and evaluation. On November 5, Rasmussen was hired on $16.5 million fast-track contract to get the project reopened in two months.
"We had to work with our team and Caltrans daily to make sure we were on schedule," says Adam Rasmussen, project manager. He says to avoid a $3,000 per day late fee, his crews had to work double shifts every day to replace and repair compromised concrete.
To help with concrete removal, Rasmussen’s subcontractor, Hydro Pressure Corp of Camarillo, CA, used a hydro-blasting machine that uses a robot arm to shoot a jet stream of water at 20,000 psi. The machine was used to blast off sections as big as 70 ft by 20 ft, and then shotcrete and epoxy was filled in where needed.
Caltrans structure representative James Shih, P.E., told me last month that Hydro Demolition is faster than traditional methods and does not damage the existing reinforcing steel. “This technique is not unique; however it is not generally used in traditional bridge demolition projects since most do not typically remove only surface concrete at such a large scale,” he said.
Besides replacing burned concrete, Rasmussen employed carbon fiber wrapping around affected outrigger beams on the north side of the connector, repaved the roadway, upgraded metal beam guardrails, installed 500 new lights, and added anti-graffiti coated paint.
Key project subcontractors included Shotcrete Systems, Inc., San Fernando, CA; and High-Light Electric, Inc., Riverside, CA.