Final design of HS2 Chiltern Tunnel’s North Portal revealed

High Speed 2 (HS2) revealed the final designs of Chiltern Tunnel’s North Portal on Tuesday, March 21^st.

The North Portal is the last of seven key structures in the tunnel’s design, which will be visible to the local communities.

Furthermore, Chiltern Tunnel is a twin-bore tunnel stretching 16km, which will make it the longest one between London and Crewe along the HS2 route.

Delivery of the North Portal’s detailed design marks a significant milestone for the project, as this was the last of the seven key structures and means that the tunnel’s entire detailed design has been completed.

The final designs for the North Portal include two perforated concrete hoods. These hoods will cover the tunnel’s exit and act as “porous portals”, extending the tunnel into open air. Their purpose will be to avoid sudden changes in air pressure as well as to prevent noise caused by high-speed trains entering and exiting the tunnels.

A simple single-storey ancillary building is also included in the design, which will be located alongside the portal and is set to house mechanical and electrical equipment. This building will be of brown color with a green roof, to blend in with the local environment.

A footpath bridge can also be seen in the project’s visualizations, a little further north from the portal.

Finally, stretching 3 kilometers north of the tunnel will be 20 hectares of newly planted land, leading to the Wendover Dean Viaduct.