Burlington Tunnel Emergency Repairs - 2008
ECI’s Client: New England Central Railroad
Completion Date: December 2008
Subcontractors: Boscardin Consulting Services
ECI was engaged by the NECR to perform emergency stabilization of the Burlington Tunnel (located under North Avenue in Burlington, VT). A sudden loss of structural integrity of the tunnel floor caused significant ground movements and longitudinal cracking at the spring-line of the 150-year-old brick lined tunnel. The railroad immediately stabilized the tunnel by flooding the unstable areas concrete. ECI was called in to design/build a permanent repair. The design consisted of a concrete bearing curb on each side of the tunnel with a reinforced concrete track structure (steel cross ties and rebar encased in concrete) to serve as a cross strut to resist the lateral earth pressures. Our scope of work included:
Scope of Work:
Evaluation of tunnel: cored through brick lining to evaluate crack depth and tunnel lining thickness, installed survey monitoring points and crack monitors; evaluated lateral earth pressures; designed permanent bracing
Removal of the temporary concrete fill (which was higher than the proposed finish floor elevation) in segments and replacing with new concrete segments.
Installation of the reinforced concrete curbs to act as a bearing for lateral forces transferred through the track structure.
Installation and alignment of the steel cross-ties and rail.
Grouting of cracks with a neat cement grout under low pressures.
The project is also described in a technical paper published and presented at the 2011 Rapid Excavation & Tunneling Conference in San Francisco.
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