North Downs Tunnel
| North Downs Tunnel | |
|---|---|
North portal, with Class 373 on Eurostar service heading to Paris | |
Interactive map of North Downs Tunnel | |
| Overview | |
| Other name | Blue Bell Hill Tunnel |
| Line | High Speed 1 |
| Location | Blue Bell Hill, Maidstone, Kent |
| Coordinates | 51°19′44″N 0°30′21″E / 51.32890°N 0.50589°E |
| Operation | |
| Work begun | 1999 |
| Opened | 2001 |
| Owner | Network Rail |
The North Downs Tunnel, also known as the Blue Bell Hill Tunnel, is a railway tunnel that carries High Speed 1 through the North Downs, at Blue Bell Hill near Maidstone in Kent, south-east England.
The tunnel is 3.2 kilometres (2 mi) long, with an internal diameter of 12 metres (40 ft) and a cross-sectional area (CSA) of 150 square metres, and descends to a depth of 100 m (325 ft) below the chalk hills. Thus, at the time of its completion, the North Downs Tunnel was both the largest (in terms of CSA) and deepest twin-track railway tunnel to have ever been constructed in the UK. Trains using High Speed 1 can reach 300 kilometres per hour (186 mph) whilst in the tunnel.