M25 Junctions 16 to 23 Widening

This section occupies most of the north-western quadrant of the M25 London Orbital motorway between the M40 and the A1(M) junctions, a distance of 22.5 miles.

The scheme involves widening the motorway from three lanes to four lanes in both directions. Already, there is a short distance of 4-lane clockwise (northbound) carriageway, from the northbound on-slip at Junction 16, as well as four-lane anti-clockwise carriageways at the southbound offslips (eastbound and westbound) at Junction 16. The remainder of this section of the motorway is three-lane in both directions.

Scheme benefits will include:

• improved journey time reliability
• improved safety on the motorway
• reduced congestion
• improved driver information

Our Scope includes:

• Widening 3- to 4-lanes in both directions, with hard shoulder
• At railway and other crossings, carriageway will drop the hard shoulder
• At Berry Lane Viaduct, just south of Junction 18 (Chorleywood) – advanced works contract to construct the additional columns, to support carriageway widening starting May 2009
• Some new and replacement noise fences adjacent to housing
• Demolition and reconstruction of footbridge, between Berry Lane Viaduct and Junction 18
• Completion Summer 2012

Section 1, between Junctions 16 and 23, is scheduled for construction between April 2009 and June 2012. This schedule is deliberately timed to coincide with the London Olympics in July 2012, so keeping to programme will be critical.

Construction of Section 1 is itself divided into three sections:

• Section 1x J16-J18 (May 2009-June 2010 – 57 weeks)
• Section 1y J18-J21 (June 2010-May 2011 – 48 weeks)
• Section 1z J21-J23 (May 2011-June 2012 – 45 weeks)

Key Facts include:

• Section 1x = 7.5 miles (May 2009-June 2010 - 57 weeks)
• Section 1y = 7.5 miles (June 2010-May 2011 - 48 weeks)
• Section 1z = 7.5 miles (May 2011-June 2012 - 45 weeks)
• Section 1 is within Buckinghamshire and Hertfordshire County Councils
• There are no Statutory Designated Ecological Sites affected