The the second longest tunnel on the route was built using four machines, with the final one Anne now breaking through 14 months after starting her drive on the second bore of the 3.4-mile eastern section.
The Northolt Tunnel will take HS2’s new high-speed trains between West Ruislip at the outer edge of the capital and the new Old Oak Common super-hub station in west London.
Skanska Costain Strabag JV crews have now shifted focus to installing the tunnel base and fitting out the route with 34 cross passages and surface headhouses that house ventilation and emergency systems.
| Northolt Tunnel Facts | |
|---|---|
| Detail | Figures |
| Total tunnel length | 8.4 miles |
| Number of TBMs used | 4 |
| Clay excavated | 4.16m tonnes |
| Concrete rings installed | 14,300 |
| TBM diameter (Anne) | 9.11m |
| Deepest point | 35m |
TBM Anne was named after educational reformer Lady Anne Byron following a public vote in Ealing, where she founded one of England’s first co-operative schools.
Richard Adam, managing director at SCS JV, said: “As we move forward, work continues at pace on the cross passages, tunnel fitout and surface structures and we are preparing to launch our final two TBMs to Euston early next year.”
Northolt is one of five deep twin-bore tunnels on the 140-mile route and the second longest behind the Chiltern Tunnel, which is 10 miles long.
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