The UK’s Southampton City Council tasked Halcrow’s Chichester-based team with helping to alleviate congestion at Millbrook roundabout - its busiest road access point to Southampton’s busy Western Docks. The regularly congested route is continually used by heavy goods vehicles resulting in frequent traffic jams at this five-arm roundabout.
Halcrow devised an innovative solution to the problem through the introduction of traffic signals on the circulatory carriageway and all its arms, major carriageway resurfacing and stabilisation, and by installing cycle and pedestrian facilities. Road user casualties at the junction were also addressed through controlled toucan crossings which replaced uncontrolled crossing points on the roundabout’s perimeter.
Other historical problems included the fact that the carriageway was initially built by using cast in-situ concrete slabs on reclaimed land, resulting in a number of voids that materialised over a long period - exacerbated by the sheer volume of heavy goods vehicles using the roundabout.
The six month commission became the council’s largest highways project in 2008 and sought assurances that it would be completed as quickly as possible, with minimal disruption to local residents, businesses and road users.
A tight deadline was set for the design and works owing to previously programmed maintenance works on the roundabout’s flyover structure. As project manager, designer and the client’s site representative, Halcrow worked closely with the wider project team to co-ordinate all aspects of the scheme.
Halcrow introduced a range of new techniques for data gathering through laser scanning. The topographical survey was undertaken by Halcrow’s geospatial team and included details of all road furniture and road markings.
Sustainability was at the heart of the project with a number of innovations such as polymer resin injections beneath unstable cast in-situ concrete carriageway slabs, and the use of epoxy liners in existing surface water drainage pipelines to avoid mass disruption and project delays.