HOCHTIEF successfully delivered the A23 Coulsdon Town Centre Improvement Scheme, building a new 1.7km section of the A23 which bypasses the centre of Coulsdon to reduce congestion. Our scope of works involved junction realignment, roundabout construction and several structures, including a road bridge and a 40m jacked box tunnel under the live London to Brighton railway.

Key features:

  • 1.7km road construction
  • Realignment of 2 junctions
  • 2 roundabouts
  • 2 span steel composite road bridge
  • 40m 8,000t reinforced concrete underpass beneath the railway
  • Replacement of footbridge over the railway
  • Environmental mitigation
  • Piled retaining walls
  • Significant utilities

It was vital that two-way traffic was maintained on the A23 throughout the contract. To form the Southern Junction, we built a new roundabout on-line and rebuilt the old A23 leading into the town centre, raising the road level by over a metre. We raised each lane progressively while traffic ran on adjacent narrowed lanes, and we completed the final wearing course at night, one lane at a time, to minimise disruption.

At Marlpit Lane Junction, we built a new bridge to divert the new A23 over local traffic. We used careful Traffic Management to keep traffic at a safe distance while we built the central bridge pier and we lifted in the steel deck beams at night to avoid congestion. We redesigned the bridge from three to two spans with smaller pile diameters, avoiding costly service diversions and reducing the programme.

We also successfully installed a 40m, 8,500 tonne concrete jacked box tunnel under the railway at Coulsdon Town Station while the station remained open. The new road opened on time and budget and the project won the 2006 Ground Engineering Award in London and a Considerate Constructors Silver Award.