Complex Repair On 101-Year-Old Tunnel

Dornan Tunnel Repairs

Dornan Tunnel Repairs

Workers repair concrete cavity and ceiling lining

Workers repair concrete cavity and ceiling lining

System 160 in action

System 160 in action

Close up of System 160

Close up of System 160

Tunnel complete!

Tunnel complete!

  • Transportation
  • Propping and Shoring
  • Richmond, CA
  • March 2015

Speak to a specialist

Andy Boorman

General Manager, Bridging

1 (443) 790 4477

Dornan Road Tunnel Reopens One Week Earlier Than Expected Using Mabey’s Propping Solution

Challenge

In June of 2013, contractors were hired to perform concrete lining rehabilitation, surface and joint repairs and chemical grouting of cracks on the 101-year-old Dornan Drive Tunnel in Richmond, CA. The tunnel serves as the main road to Miller Knox Regional Shoreline and the Point Richmond community and handles both vehicular and pedestrian traffic.

Upon inspection of the tunnel, contractor found cracks in the concrete lining of the tunnel’s inner surface and discovered a room-sized void above the ceiling of the tunnel’s concrete lining. It appeared that the original work failed to fill this gap during the original 1912 construction. As a result, the tunnel lining was just two inches thick in areas, with no structural reinforcement. The city x-rayed the tunnel lining and discovered several voids in the concrete that needed to be treated and reinforced. For the safety of the community and the workers, the tunnel was closed for several weeks while structural repairs were made along with enhancements to the concrete lining of the tunnel as originally scoped.

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Solution

Mabey met with contractors on site to see the tunnel and discuss the scope of the project. The contractor described the structural failures at the tunnel lining and was having trouble figuring out how to safely support the tunnel to make the repairs. The arched shape of the tunnel would require a custom form to be built to support the liner while they filled the 163 square foot void with concrete grout. However, Mabey proposed its System 160 System to support the tunnel’s arch without any custom form work needed. Mabey engineers went to work and developed a PE-certified plan to brace the tunnel’s arch and along the sides of the structure so repair work could commence.

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Results

Since System 160 has a high-load capacity of up to 45 kips, it supports a lot with less. It requires a low number of components to create the prop so assembly and disassembly times are short which affects the overall timeline of the project. Additionally, the variety of extensions and screw assemblies available with System 160 make it extremely flexible in achieving any height requirement. All these factors helped to save the contractor days in production time by providing a secure, safe support structure that enabled the tunnel to reopen days earlier than expected.

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Downloads

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