Channel Tunnel Rail Link (HS1)

TECHNICAL OVERVIEW

This project includes several outsized structures:

• Lot C410: the North Downs rail tunnel, the largest of its kind ever built in the United Kingdom. It runs, as deep as 80 metres below ground, under the Buckmore Park Leisure Centre, the A229 motorway, and two residential districts (Blue Bell Hill and Kit’s Cotty). The ground contact points are located in areas subject to stringent environmental protection requirements, which had to be factored into the project’s design and construction phases. The assumption underlying the studies phase was that trains would travel at a top speed of 270 kilometres an hour, with the possibility of increasing this top speed subsequently to 300 kilometres an hour. Study findings and safety regulations led to the development of evacuation footbridges on either side of the tunnel.
• Lot C350: the viaduct spanning the Medway, whose 152-metre central span was a world record at the time for high-speed rail crossings. All 24 piers rest on concrete piles. Each of the two piers in the river include 19 piles 30 metres long with a diameter of 2 metres.
• Lot C310: subsequently, VINCI Construction Grands Projets was awarded a contract to design-build a bridge a little over a kilometre long (Thurrock), two viaducts (Rainham and Aveley), nearly 14 kilometres of rail platforms in London’s eastern suburbs, and 14 engineering structures of various kinds. Thanks to the experience acquired on the first two lots, we carried out the design, thereby showcasing the abilities of the integrated design department at VINCI Construction Grands Projets.

The main difficulty in this new contract was the project site in London’s eastern suburbs, which was a busy urban setting criss-crossed by multiple roads, rail lines, and utility networks (communications, gas, power). One of the most delicate parts of the project was the Thurrock Viaduct, which runs below the Elisabeth II Bridge, spanning the London-Tilbury rail link and the M25 motorway (London’s ring road) at a place where 150,000 vehicles pass every day. This is an incrementally launched structure, a method chosen to minimise traffic interruption.

Also as part of this lot, we found a use for waste materials. The project team re-used several tonnes of inert waste (lightweight concrete blocks) for subgrade fill, piled slabs, and worksite paths. The light-concrete subgrade, built across marshland and along existing rail tracks, helped to minimise soil compaction and thereby improve conditions for the building of structures. On November 6, 2003, this effective recycling initiative earned the consortium a Green Apple Award in the House of Commons. This prize rewards companies and institutions for the quality of their environmental protection initiatives. Subsequently, the Thurrock Viaduct was awarded a prize by the Concrete Society in the civil engineering category.

IMPACT

On Wednesday, July 30, 2003 at 12:35 PM, French time, in Kent between Folkestone and Fawkham, Eurostar established a speed record in Great Britain: 334.7 kilometres an hour on the first section of the British high-speed rail line (or to be more precise, in the Nashenden Valley, on a segment of the CTRL).

Since September 28, 2003, the inauguration date for this first 74-kilometre section of the CTRL, Eurostar trains have been travelling on this new line as part of its passenger service at an average speed of 300 kilometres an hour, thereby reducing travel time from central Paris to central London by 20 minutes. Not only is the British capital only two hours and fifteen minutes from Paris, but also one hour and twenty minutes from Lille and one hour and fifty-one minutes from Brussels.

The CTRL project, now known as High Speed 1, was a key project in the United Kingdom. This new line brought London closer to continental Europe.

In the United Kingdom, it facilitates domestic train travel and has contributed to the development of London’s eastern boroughs. Project participants certainly turned in a stellar performance.