Comprising 4.5km in length, the 2-lane dual carriageway was widened to 3 lanes without any land take. The constraint of the existing boundary meant that a number of retaining structures were included in the illustrative design.
Appointed by a joint venture consisting of BAM Nuttall and Morgan Sindall, John Bowes as project director was also able to offer value engineering and win strategy support. Time and costs were at a premium on this scheme, and therefore we aimed to retain as much of the existing infrastructure, reducing the extent of works and minimising the impact of the construction on the operation of the live network.
Our design retained as many existing features as possible and minimised the use of large construction plant. This included retention of drainage, safety barriers and lighting within the central reserve where feasible. The use of cantilever sign gantries removed the need to amend the drainage and safety barrier along the central reserve reducing the length of central reserve works from 3.9km to just 240m at existing structures.
The project team were challenged to find an alternative retaining solution due to the importance of reducing costs of construction, as well as the programme. The innovative solution developed by John Bowes was the creation of a concrete gabion using individual rectangular reinforced precast concrete manhole segments which required minimal compaction and halved the cost of installation in comparison to normal alternatives. They were also filled with as-dug material from site, significantly reducing export of materials off site and reducing the carbon footprint.
The constrained corridor minimised the available space for retaining structures and drainage. In addition there was a requirement to retain 2 lanes of traffic in each direction which meant that working space was a challenge during normal working hours. John utilised his traffic management experience to provide a 3 + 1 contraflow layout which provided 2 lanes of safe working space. In addition, the value engineering undertaken at junction 7 allowed the work to be undertaken in two main stages from five and reduced the construction programme by 14 months. John developed the traffic management strategy in contract and agreed this along with the 40mph speed limit with Highways England’s Operations Team.
The value engineering undertaken at tender stage reduced the tender price by 15% which was a key reason the tender was successful.
Quote – “We all thought the illustrative design could not be improved, John used his lateral thinking and tenacity to find over £4m of savings” – Simon Spink, BAMN Nuttall Construction Manager
