HS2 completes second Wendover Viaduct deck slide

HS2 has completed its latest stage in its complex year-long project as it slid a part of the half-kilometre Wendover Dean Viaduct bridge deck into position in Buckinghamshire.

The viaduct is being assembled in three stages and will eventually stretch for 450 metres. Over a 20-hour period last week, engineers slid the 3,130-tonne structure 270 metres, using Teflon pads to reduce friction - A material usually seen on the surface of a non-stick frying pan.

Each section of the of the assembly will see them pushed out from the north abutment, before the next section is attached behind it, with the sections ranging from 90 metres to 180 metres.

This process will mean that the weight of the deck will increase with each push up, eventually weighing nearly 3,700 tonnes by the end of the year.

The Wendover Viaduct is one of 50 major viaducts on the HS2 project and is being built at a slight gradient. This has meant the deck is being pushed slightly uphill to help maintain control.

HS2 Ltd senior project manager Ben Sebastian-Green said: “It’s great to see so much progress at Wendover Dean Viaduct over the last few days – with all the piers and the first three slides now done. The narrow site has always made it a challenging place to build, but I’m really impressed by how everyone’s pulled together to get us where we are today.

“Once complete, the viaduct will form a crucial part of the HS2 project - carrying fast trains between London and Birmingham and freeing up space on the existing mainline for more local and freight services.”

The Wendover Viaduct is unique as once it is fully constructed, it will be the first major railway bridge in the UK to be built with a ‘double composite’ structure – A slightly less carbon-intensive concrete and steel.

The ‘double composite' approach has proved popular on mainland Europe, and it is expected to cut the carbon footprint of the structure by around half.

The viaduct will be supported by nine evenly spaced piers, some of which are up to 14 metres high and all of which are now complete. These were formed from a series of hollow pre-cast concrete shells – manufactured in Northern Ireland - which were placed on top of each other and filled with concrete and steel reinforcing.

Wendover Dean Viaduct is one of 500 bridging structures being constructed by HS2 including the Colne Valley Viaduct, which will become the longest in the UK.