High Speed 1 (HS1) is the 68-mile (109-kilometre (km)) high-speed railway between London and the UK side of the Channel Tunnel. Supporting domestic passenger traffic alongside freight and international passenger traffic, the line has boosted local and national growth in the past 10 years, with ambitions to rival low-cost airlines in the future.

Discussed since the 1970s, financial and political pressures delayed the Channel Tunnel Rail Link for decades, with construction finally approved in the mid-1990s.

AECOM was commissioned to provide all civil and railway engineering design for the proposed high-speed rail link between central London and the Channel Tunnel. This covered all necessary infrastructure excluding the bored tunnels and station buildings. AECOM provided preliminary designs for all civil surface works and all railway works, to enable detailed construction planning and costing of a conforming bid — together with assessing and designing an alternative.

In addition, AECOM worked as the contractor’s designer on the Kent section of the route, within the vicinity of Ebbsfleet International Station. This included designing Pepper Hill tunnel — which carries the rail link under a major A2 trunk road — and securing the necessary planning permissions. AECOM also provided technical and consultancy services for the twin-bored tunnelled sections of the route in east London, located beneath existing rail surface lines and settlements.