The Weston Hills Tunnel is a 230m twin road

tunnel A tunnel is an underground passageway, dug through surrounding soil, earth or rock, and enclosed except for the entrance and exit, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube cons ...

under the Weston Hills near

Baldock Baldock ( ) is a historic market town and unparished area in the local government district of North Hertfordshire in the county of Hertfordshire, England, where the River Ivel rises. It lies north of London, southeast of Bedford, and north n ...

Hertfordshire Hertfordshire ( or ; often abbreviated Herts) is one of the home counties in southern England. It borders Bedfordshire and Cambridgeshire to the north, Essex to the east, Greater London to the south, and Buckinghamshire to the west. For govern ...

. It was constructed as part of the

A505 The A505 is an A-class road in England. It follows part of the route of the Icknield Way and the corresponding Icknield Way Path and runs from Leighton Buzzard in Bedfordshire to the A11 Abington Interchange North in Cambridgeshire. Route ...

Baldock bypass. A public inquiry was held in 1995, and in 2002 the government granted permission to build the road. Construction started in April 2004 and the bypass and tunnels opened on 16 March 2006 The bypass as a whole, including the tunnel, cost £43 million. The tunnel itself was constructed using a

cut and cover A tunnel is an underground passageway, dug through surrounding soil, earth or rock, and enclosed except for the entrance and exit, commonly at each end. A Pipeline transport, pipeline is not a tunnel, though some recent tunnels have used ...

method, during which the hill was cut away and the concrete tunnel structure then put in place. The hillside was then re-filled in over the top - se
Bypass Construction Gallery
The purpose of the tunnel at this position is to reduce the gradient of the road, and to preserve the visual line of the hills and provide crossing points for wildlife such as deer. The chalk cuttings for the tunnel have become a haven for butterflies which are native to the area.

References

{{reflist Transport in Hertfordshire Road tunnels in England Tunnels completed in 2006 Tunnels in Hertfordshire Baldock