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Hertfordshire County Council


High Speed 2 (HS2) is a Department for Transport project to build a new high speed railway between London and Birmingham, with later extensions to Manchester and Leeds.

 A section of the line – due to open in 2026 – passes within Hertfordshire's county boundary and requires significant construction works, namely the Colne Valley Viaduct and Chiltern Tunnel Southern Portal.

M25 lane closures

Initial HS2 construction work has started in Hertfordshire with lane closures on the M25 while new access roads are built.

Stay up to date with lane closures and diversion routes

Ground investigations and archaeological digs

Ground investigations and archaeology surveys are being undertaken in the fields alongside the M25, between Chalfont Lane and Hornhill Road and south of Chalfont Lane.

The ground investigations, carried out by Scottish and Southern Electricity Networks, will inform where utility services are placed.

The archaeology survey, carried out by COPA, involves digging trenches to identify whether any prehistoric or Roman remains survive within the site.

HS2 receives Royal Assent (Feb 2017)

HS2 received Royal Assent and is now an Act of Parliament.

Preparatory works for the scheme are currently underway. We continue to work closely with Three Rivers District Council.

How HS2 will impact Hertfordshire

We recognise the need to improve our national infrastructure and we broadly support the scheme. However, we do have particular concerns about the impact the construction of the HS2 line will have on the local area.

The HS2 proposals that will impact on the county include:

  • constructing the Chiltern Tunnel and the Colne Valley Viaduct
  • excavating material to form the West Hyde embankment – a large new hill to the southwest of West Hyde
  • ongoing round-the-clock construction work for approximately 6 years
  • building three large construction compounds within the county that would house 250 and be in use for up to 12 years.

How Hertfordshire County Council has responded to HS2

Our priority is to make sure that, if HS2 does go ahead, it does so in a way that minimises any negative impact on Hertfordshire's residents, wildlife, and resources.

We have been working with HS2 and other affected authorities including Three Rivers District Council to address our concerns and objections. We are encouraged by the assurances given by HS2 which gives us greater clarity over the scheme and comfort regarding our concerns.

Assurances given by HS2

HS2 has said it will:

  • monitor air quality at three key construction sites
  • provide new habitats for rare wildlife, such as corn buntings, and observe populations
  • monitor the amount of aggregate and waste materials released into the air and surrounding areas where excavations are taking place
  • address concerns about traffic management around construction compounds and site
  • ensure the construction sites are appropriately screened while work is carried out and restored once work is complete.

Schedule 17 consents for Three Rivers District Council

Bringing into use temporary south bound slip road- June 2018- supporting documents

Bringing into use for temporary north bound slip road- June 2018- supporting documents

Bringing into use for temporary link road- June 2018 - supporting documents.

SSE substation February 2018 - Supporting documents and decision notice

Earthworks at Chalfont Lane S17 December 2017 – Supporting documents. Submission withdrawn

Site Restoration S17 December 2017 - Supporting documents and decision notice


Schedule 17 consents for Hertfordshire County Council

Lorry Route Approval December 2017- supporting documents and decision notice