HS1 (Channel Tunnel Rail Link)

HS1 (Channel Tunnel Rail Link)
  • high speed rail link 67 mile
  • diameter fans 1600mm
  • annual passengers 5.8 million

HS1 (also known as the Channel Tunnel Rail Link) is a 67-mile high-speed railway linking London with the Channel Tunnel. The line carries international passenger traffic between the United Kingdom and mainland Europe; it also carries domestic passenger traffic to and from stations in Kent and east London, and Berne gauge freight traffic.

Project Brief

Exyte Hargreaves was engaged to manufacture and install ventilation systems (including fans, Saccardo nozzles and their supporting structure) in the service shafts and portal buildings. We also completed the manufacture and installation of ventilation ductwork systems in the service shaft head buildings and the installation of Jet Fans.

Specialist ventilation work by Hargreaves included environmental comfort control and emergency smoke exhaust. The scope of work covered public areas, administration offices and car parks.

Work in the Service Shafts

The Service Shafts consisted of upline and downline shafts each with a pattern of 5 number 6M x 6M control dampers horizontally and vertically. These connected and isolated the two rail tunnel bores to give full flexibility of air movement. They could react to various emergency situations. The air is moved by a 2M diameter axial flow fan installed in each of the shafts with attenuators both onthe tunnel side and the atmosphere side. These attenuators are approximately 6M x 6M and are connected to the fan using 3M long square to round transition sections.

All the installation was completed using a crane with access down the shaft and included manufacture and installation of steel access and support floors and interconnecting cat ladders.

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Work in the Portal Buildings

These portal buildings were located along the river Thames where the rail line crosses under the river. The use of ventilation shafts was impractical so close to the river so a system of Saccardo nozzles was designed to give emergency coverage to the tunnel.

A Saccardo nozzle is a forced draught ventilation system which induces a flow in a tunnel over long distances. For each bore of each portal 4 off 1600mm diameter fans introduce the air into the tunnel roof via a very long tapering duct (Saccardo Nozzle). This allows the fans to be outside the tunnel giving easier maintenance. Hargreaves manufactured and installed the fans along with their supporting structure.

Shaft Head Buildings and Jet Fans

Completed: 2006 | Project Value: £3.8 million

At nine positions along the rail route, at shafts and portals, service buildings were built. These buildings, as well as providing emergency access to the tunnels, housed the electrical switchrooms required to run the system. The contract included the manufacture and installation of ductwork to ventilate these buildings. A number of jet fans were also required at set locations along the rail tunnel wall.

"The main function of the ventilation systems was to either supply or extract air from the tunnels in the event of incident conditions. Sophisticated computerised control will enable maximum flexibility of use and be able to provide air for passenger comfort in a stationary train and for maintenance work in the tunnels"

Ryan Gorman

Operations & Business Development Director


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