The biggest challenge for this project was dealing with the high groundwater pressures. The Lee tunnel is the deepest tunnel ever built in London. It includes five shafts that run as deep as 95 m (312 ft) and need to handle groundwater pressures as high as 8 bar.
The concrete of the precast segmental lining contains 30 kg/m³ Dramix® 3D 6535 BG steel fibers. The permanent lining in the five shafts contain 40 kg/m³ Dramix® 3D 65/35 BG. For the inner permanent lining of the tunnel, the customer chose 40 kg/m³. Dramix® 5D 6560 BG because of its excellent bending hardening properties. In total Dramix® steel fibers replaced over 17 000 tons of traditional reinforcement in the secondary lining alone.