TEC Tunnel Engineering consultants

Project description

For the running tunnels, a twin bored tunnel is applied that follows the street pattern as closely as possible and is lowered to a great depth to minimise the construction effects (since high water tables and soft soils had to be dealt with). The total length of the bored tunnel part is approx. 3.2 km; the outer diameter is approx. 7 m. Since the streets are very narrow the tunnels are bored with only 0,5 x diameter clearance. On some sections in the South the tunnels even had to be bored above each other because positioning the tunnels next to each other was not possible.

Scope of work

The consultancy services included:

• Feasibility study in which a single large diameter bored tunnel was compared against twin smaller diameter bored tunnels in terms of costs and impact on the historic structures
• Pre-design, final design, tender design and detailed design
• Tender documentation and consultation
• Contract management and supervision