Devil’s Slide Tunnel Project

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Zircon end-users really appreciate that they can call or email us with their questions and quickly get answers from someone who really knows the products very well. One day when I was covering a shift on Zircon’s end-user help desk, I got a call from the crew who were building the Devil’s Slide tunnel.

Famous for beautiful views, much of California’s Highway 1 runs along cliffs on the Pacific Coast, but mudslides from the steep terrain above Highway 1 often close sections of the road for months at a time, including here at Devil’s Slide.
Famous for beautiful views, much of California’s Highway 1 runs along cliffs on the Pacific Coast, but mudslides from the steep terrain above Highway 1 often close sections of the road for months at a time, including here at Devil’s Slide.

They were having trouble using the Zircon MT6 to locate rebar in the ceilings of the mechanical room. They needed to miss the rebar to install ventilation. The problem was that the tool seemed to indicate metal everywhere.

Because Devil’s Slide is such a large infrastructure project, and in earthquake country, a massive amount of steel exists compared to a typical concrete wall or floor. I decided to go to the site to see if I could help them. Please see photos and captions for the solution we found.

Entrance to Tunnel – The State of California decided to build 2 tunnels; 1 for northbound traffic, and 1 for southbound traffic.
Entrance to Tunnel – The State of California decided to build 2 tunnels; 1 for northbound traffic, and 1 for southbound traffic.

The 2 tunnels are connected with 10 mechanical rooms, and this is the first location where they needed to use MT6. The California State contract requires that the workers must scan the concrete with a metal scanner such as the MT6 before penetrating it with a fastener to install this ventilation system.
The 2 tunnels are connected with 10 mechanical rooms, and this is the first location where they needed to use the MT6. The California State contract requires that the workers must scan the concrete with a metal scanner such as the MT6 before penetrating it with a fastener to install this ventilation system.

Each tunnel is approx. 4,200 feet long (about 4/5ths of a mile). It is a much more challenging application for using the MT6 compared to a concrete and steel building or slab because of the massive amount of rebar. I told Zircon’s engineers that instead of a concrete wall with steel reinforcement, Devil’s Slide Tunnel is more like a steel wall with concrete filler.
Each tunnel is approx. 4,200 feet long (about 4/5ths of a mile). It is a much more challenging application for using the MT6 compared to a concrete and steel building or slab because of the massive amount of rebar. I told Zircon’s engineers that instead of a concrete wall with steel reinforcement, Devil’s Slide Tunnel is more like a steel wall with concrete filler.

Before using any scanner the workers hit rebar about 1/3 of the times they drilled, so they would have to try a new location and patch the unneeded hole, as you can see in this first of ten mechanical rooms. But for mechanical rooms 2 – 10 (using a Zircon MT6) they were about 99% successful in missing the rebar. Rather than focusing the MT6 to finding metal, instead we looked for the weakest signals, and that system worked.
Before using any scanner, the workers hit rebar about 1/3 of the times they drilled, so they would have to try a new location and patch the unneeded hole, as you can see in this first of ten mechanical rooms. But for mechanical rooms 2 – 10 (using a Zircon MT6) they were about 99% successful in missing the rebar. Rather than focusing the MT6 to finding metal, instead we looked for the weakest signals, and that system worked.

The next job for the MT6 was in the main tunnels. Again the workers needed to scan before installing fasteners for Jet Fans, but now they would be high up in a bucket. The light weight of the MT6 was perfect for performing multiple overhead scans, and they appreciated that it was very quick to scan and determine the weakest magnetic field where they could install a 4 ½ fastener and miss the rebar.
The next job for the MT6 was in the main tunnels. Again, the workers needed to scan before installing fasteners for Jet Fans, but now they would be high up in a bucket. The lightweight nature  of the MT6 was perfect for performing multiple overhead scans, and the workers appreciated that it was very quick to scan and determine the weakest magnetic field where they could install a 4 ½ inch fastener and miss the rebar.

When Zircon was doing research and development for our metal detectors, we took a prototype unit to the crew at Devil’s Slide. They were very impressed with the new features and also suggested a loop for a wrist strap to prevent the tool from dropping. A lanyard loop has since been incorporate into future designs.
When Zircon was doing research and development for our metal detectors, we took a prototype unit to the crew at Devil’s Slide. They were very impressed with the new features and also suggested a loop for a wrist strap to prevent the tool from dropping. A lanyard loop has since been incorporated into future designs.

The Devil’s Slide project is a great example of showcasing the ease of use, functionality, and performance of Zircon’s tools. Whether you’re a do-it-yourselfer or a professional tool user, we’re happy to answer your Zircon tool questions. Please also follow us @zircontools or like us on Facebook,.

One of Zircon’s long-time consultants, Kurt Stauss works with the pros who need and use Zircon tools on the job. A seasoned tool and industry expert, Kurt travels across the globe to demonstrate how Zircon tools is the solution to everyday problems.