2. A3 - dual carriageway link between London and Portsmouth 6.5km new road, 1.77km in bored tunnel £371 million Construction started January 2007 Project finish date 2012

5. Where?

11. Construction Overview Twin Bore 2 lane Tunnel Tunnel Length – 1.2 miles Depth – Varies between 20 – 60m 7.3m wide 2 lane carriageway Estimated Earth Excavation – 300,000 cubic metres Longest non-estuarial crossing in England

12. Solution Adopted Slope Stability Soil Nails Geogrid Reinforcement Minimising Visual Impact Soil Pouches Place Soil and Vegetation Hydroseed Spray

13. Solution Adopted continued….. Structural Reinforcement for Tunnel Face Rock Nails/Bolts Short Concrete Grout Ground Anchors Long High Tensile Steel

14. Solution Adopted continued….. Sprayed Concrete Lining (SCL) Roof Supporting Spiles Primary sprayed concrete shell Waterproofing Membrane Reinforcement Steel Cast Concrete lining Shotcrete 200mm thick

15. Alternative Methods New Austrian Tunneling Method (NATM) Tunnel Boring Machines (TBM) New Tunnel PLS (Pre-Lining Support)

16. What Will It Look Like?

17. Thankyou for Listening Any Questions?