Following Government development consent, the construction of a section of Smart motorway between Heathrow and Reading is now due to start before March 2017, with expected completion in 2021/22. The £800m scheme will see an upgrade to the busy 32-mile section from Cranford Park, near Heathrow, to Theale in Berkshire, with concrete barrier constructed along the length of the project.
A joint venture between Balfour Beatty (60%) and Vinci (40%) will deliver the barrier construction which has been designed by a CH2M and Arcadis joint venture. The designers have already taken advantage of the industry-unique Technical Query Service offered by BBS for planning and overcoming potential obstacles.
As part of the works, 11 overbridges will be replaced with larger span structures and six underbridges will be widened to accommodate four lanes. This has presented an opportunity for the newly developed Bridge detail with revised foundation requirements, developed by BBS in response to a need identified by Highways England, to be disclosed to the market. The new developments will allow for a dramatic reduction in minimum barrier length and a foundation detail which will be much easier for the contractors to construct – increasing productivity and reducing costs.
In concluding the DCO (Development Consent Order) initiated by Highways England in 2015, Transport secretary Chris Grayling has now given his seal of approval, completing the pre-construction regulatory process.
The use of concrete barrier on the M4 scheme is another opportunity to realise the low maintenance and increased safety currently demonstrated on other successful Smart motorway schemes. In April 2015, a section protected by a steel VRS system between J11-12 was closed when a HGV crossed over from the westbound to the eastbound carriageway, overturning and spilling cement and diesel onto the road surface.
Whilst the majority of vehicle restraint systems employed by Highways England on the UK network are not designed to withstand an impact from a HGV, concrete barrier has demonstrated an excellent safety record beyond its H2 containment rating in terms of preventing cross-over incidents, and repairs within the central reserve have become a rare occurrence.