Case Study

Junction 16-17, M25 - HS2 Enabling Works


  • Location: Maple Cross, Hertfordshire
  • Client: Osborne


The scheme includes construction of new slip roads on and off the M25, widening of the existing Chalfont Lane and construction of new carriageway to accommodate local residents during the HS2 construction phase. Astaunton were appointed as the Drainage and Groundworks Contractor for the scheme.

Services Provided

  • Over 3.5km new surface water drainage, pipe sizes ranging from 150mm diameter to 1200mm diameter, up to 6m depth
  • More than 80no precast chambers, from 1050mm diameter to 3000mm diameter
  • Approximately 200no surface water gullies
  • 3km of narrow filter drain
  • Construction of geocellular soakaway, petrol interceptor and storage tanks
  • Installation of 7.5km of precast concrete kerbs and combined kerb drain units
  • Concrete headwalls - cast in-situ and precast
  • Gabion wall construction
  • Maintenance lay-bys and footpaths


With the scheduled construction of the Chiltern Tunnel and the Colne Valley Viaduct in South West Hertfordshire due to commence a mile southbound from Junction 17 on the M25, close to the village of Maple Cross, substantial preparations are necessary to accommodate future construction traffic whilst minimising inconvenience to local residents and road users.

astaunton is incredibly proud to be playing a role in this vast project. With diligent planning and preparation in place, we are confident that these works will be delivered on time and to the same high standard that astaunton insists on in all its projects.

An investmentFor the Future