The original St. Clair River Tunnel was completed in 1891 between the province of Ontario, Canada and the state of Michigan, USA. At that time the tunnel was the longest subaqueous tunnel in the world, built with the world’s largest tunnelling shields. In the late 1980s, CN Rail required higher tunnel clearances for double-stacked container traffic, so both new and enlarged tunnel alternatives were investigated. A new parallel tunnel, north of the existing tunnel, was chosen on the basis of engineering, environmental and socio-economic criteria.
The project presented unique challenges in planning, permitting, approval and implementation. An environmental impact report was prepared in accordance with both the requirements of Ontario province and MichiganState. Since the tunnel straddles the Canadian-US Border, review of 60-year old US legislation was required, which culminated in final approval signed by the US President. The new tunnel is 1844 m long with an internal finished diameter of approx. 8.2 m. The profile just cleared the shale bedrock. Excavation was carried out with an earth-pressure balanced Tunnel Boring Machine (TBM) through weak clay with 4.5 m shallow cover. The tunnel lining is one-pass bolted, gasketed concrete segments.
In order to fast-track implementation, a “negotiated compressed process” (NCP) was developed by Klohn Crippen to achieve the target completion date. NCP simulated acquisition of items that would apply had the contractor procured these items directly. It provided the client with the advantages and cost control of competitive bidding and simultaneously with innovative designs and construction methodologies. Consequently the project schedule was compressed, and the tunnel boring machine, tunnel liner segments and other critical items were procured before completion of the final design and award of the contract.
- Feasibility studies
- Geotechnical and geological review
- Permitting and environmental approvals
- Preliminary engineering assessment of TBM
- Construction scheduling & planning