Written evidence submitted by Highways England

About Highways England

  1. Highways England is the government-owned company responsible for operating, maintaining and improving England’s 4,300 miles of motorways and major A roads, which make possible journeys totalling 85 billion miles a year. The network is relied on by communities and businesses on a daily basis, with more than nine in 10 businesses within 10 miles of the network and 90 per cent of the population living within 6 miles. Highways England is part way through the Road Investment Strategy 2015-2020, an ambitious £15 billion plan to invest in the SRN to boost the economy, connect communities and to keep England moving. There are over 45,000 people employed in the highways industry, and many more jobs rely on the connections it creates. There is a clear commitment to reduce the number of people harmed on England’s roads, and this underpins everything the organisation does. Highways England also strives to be at the forefront of road infrastructure and new technologies, including delivering smart motorways, supporting the use of electric and autonomous vehicles, and using new materials to deliver a quieter, more environmentally friendly road network.


Executive summary


  1. England’s strategic road network has high-levels of resilience to hot weather. Extended spells of very high temperatures can have an impact on our physical assets and also on those people who travel and work on our roads. As climate change causes temperatures to rise our adaptation plans are designed to ensure that our network remains resilient and that our customers and road workers remain safe.


  1. Our work to maintain resilience to heatwaves can be characterised in four broad areas:





  1. Highways England is the government-owned company responsible for operating, maintaining and improving England’s 4,300 miles of motorways and major A roads. Our top three imperatives are safety, customer service and delivery. During periods of extreme weather we will strive to ensure that traffic is kept moving and that road users are kept safe. We continually assess the operation of the network to deal with any issues as they arise, and plan for future changes in temperature through comprehensive standards replicated across the industry.


The evidence base


  1. Our Climate Change Adaptation Strategy and Framework sets out the work we are doing to adapt to a projected rise in temperatures, and a greater prevalence of heatwaves. The UK Climate Impacts Programme (UKCP09) provides the latest projections on the future climate of the UK up to 2080, estimating that the average summer temperature will be between 2.2°C and 6.8°C higher in the south and the hottest day will be between 8°C and 12°C higher. UKCP18 will further inform our work.


  1. Our Adaptation Framework Model provides a process to identify our activities affected by a changing climate, determine associated risks and opportunities, and identify preferred options to address them. The seven stages are:



  1. This process has allowed us to identify the assets on the SRN that could be at risk from extreme temperatures. The Climate Adaptation Risk Assessment Progress Update – 2016 highlights vulnerabilities and our adaptation progress in appendix 1, covering such assets as gantries, bridges and road surfaces and the actions we are taking to ensure their resilience.




Safety and well-being


  1. Safety is about maintaining assets on the strategic road network. Our key priority is to keep the network moving, and the best way to ensure this is through appropriate management of the SRN.


  1. We keep customers informed about conditions so that they can adequately prepare for their journey. This includes driving in particular weather conditions, and ensuring that their vehicles are road worthy (through checks before they travel.) We offer seasonal advice, including through public campaigns and through social media.


  1. Highways England provides advice to drivers on the network, alerting them to delays on the network. This helps drivers to make informed choices about their onward journeys. Our 1,500 traffic officers patrol the network to deal with any incidents on the network. We have a target to ensure that 85% of incidents on the motorways are cleared within the hour, a target reached in the most recent reporting period (2016/17).


  1. We strive to respond to incidents quickly and we work with local partners to provide welfare if required. We work to manage incidents on our roads in order to reopen lanes as quickly as possible, removing trapped traffic wherever possible. Where vehicles and occupants are static on the motorways and trunk roads for long periods of time, our Area teams will provide support and assistance to the regional control centre (RCC) and the police as requested. Options for delivering welfare involve supporting Local Resilience Forums and emergency services to meet any necessary welfare needs. There is no requirement under the Civil Contingencies Act (2004) for Highways England to directly plan for and respond to customer welfare needs during emergencies. 


Keeping the network moving


  1. The strategic road network (SRN) is made up of a huge and varied range of physical assets, including over 20,000 bridges and other structures, over 3,500 electronic messaging signs and over 25,000 miles of ditches and drainage assets. More than 70,000 sensors, including traffic sensors, cameras and weather stations, help us to monitor the network. Our operational response to major weather events is enhanced via these asset-monitoring technologies.


  1. We are currently part way through delivery of the first Road Investment Strategy (2015-20) and preparing for future road investment strategies. Five year funding cycles allow us to take a longer term view of the strategic road network ensuring that it remains fit for purpose in a changing climate.


  1. Highways England develops and publishes a set of design requirements and specifications.  These documents are written specifically for use by Highways England, Transport Scotland, the Welsh Government and the Department of Infrastructure Northern Ireland.  The documents are available at and are used by local highway authorities throughout the UK. They are commonly referred to as the Design Manual for Roads and Bridges (DMRB). 


  1. The DMRB is widely recognised as “best in class”, and is updated when necessary and in response to changing conditions (and will be updated in its entirety by the end of the first roads period in April 2020). 


  1. Since 2016, we have been improving how we manage our network, through a programme called Asset Delivery. Our intention is to bring in-house work to assess the condition of assets, making decisions about maintenance and coordinating repair work. This has been done across almost half of our operational areas.


Severe Weather Plans


  1. Highways England receives weather forecasts throughout the year, informing how we manage the network. During the summer, Area teams (there are 14 operational areas across the network) monitor forecasts identifying weather events that could impact upon the network.


  1. We identify locations which may be susceptible to problems. These may be due to issues such as road construction type, expansion joints within sections of concrete roads, or structures. The Vulnerable Location Schedule records these, along with information on enhanced monitoring and procedures to address any damage. We also identify the best solutions to mitigate or manage the risk.


  1. As with any type of extreme weather, Highways England offers advice to road users on how to prepare for journeys when driving in such conditions and we routinely update road users on any delays on the network. 


Future of the network




  1. Highways England has robust processes in place for designing, constructing and maintaining bridges and other structures. These processes take account of a range of climatic conditions, including high temperatures, over the long service life required for bridges (typically in excess of 100 years). These are published in the DMRB.


  1. Highways England has adopted Eurocodes for the design of new structures. These are pan-European standards which cater for a wide range of climatic conditions. They are underpinned by research and have had extensive peer review in the UK and across Europe. Eurocodes adopt a similar structural design range of maximum shade temperatures, dependent on location, which are then adjusted for the type of structure. For example:



Maximum shade temperature

Bridge type adjustment range

Resulting upper design temperature range



+2oC to +16oC

37oC – 51oC



+2oC to +16oC

35oC – 49oC



  1. These temperature ranges have been assessed as sufficient for all structures based on current climate change projections (under UKCP09) but are kept under review.


  1. Bridges and other structures are subject to thermal movements such as expansion or contraction. Depending on the form of construction, components such as bearings and joints are incorporated in the design to accommodate temperature-induced effects. These components are reliant on a programme of routine maintenance to be effective.


  1. All bridges and other structures are inspected in line with the published guidance in the DMRB. This includes a general inspection every two years, and a more detailed principal inspection every six years, which identifies and records defects in construction materials. There is very little evidence of significant structural defects associated directly with prolonged high temperatures.




  1. There are two main types of road surface. Hot Rolled Asphalt bituminous surfacing (HRA) was laid until the 1990s and had a tendency to “rut” under the action of traffic during very hot weather. This was caused by the fine aggregate rolling within the bituminous material which allowed the surface to deform. Modern HRA (complying with Highways England specification) is formulated differently and uses angular crushed rock fines and bituminous binders to make it more elastic and less likely to deform at higher temperatures.


  1. Thin Surfacing Course Systems (TSCS) is Highways England’s preferred surfacing option. These materials do not rut because they contain coarse angular aggregate bound together with bituminous material. It is a requirement of our surfacing specification that they are resistant to rutting at high temperatures before being certified for use on the SRN. This type of surfacing covers overs 50% of the SRN.


  1. Surfacing is typically designed for road temperature ranges of -10C to 50C. Road temperatures are different to air temperatures given the absorption qualities of the surfacing materials.


  1. Concrete surfaces form less than 4% of the SRN.  Those constructed in the 1950s to 1980s are mostly formed of jointed concrete slabs connected to one another by steel dowel bars. Expansion of the concrete during hot weather is accommodated by the joints between slabs closing up. However, over time, many of these joints can seize up. Maintenance and inspection of our road surfaces (published in the DMRB and our specification) recommends that the joints are kept free of debris and are replaced every five to ten years.


Other assets


  1. The Climate Adaptation Risk Assessment Progress Update 2016 identifies assets potentially at risk. For gantries, the potential impact of temperature changes on structures is considered low as the extreme temperatures do not greatly exceed the existing design guidance. We will continue to monitor these assets.


  1. There is minimal risk to Highways England’s electronic and static signs during their design life. A new standard has been adopted to future-proof new assets.


Further reading


Highways England, Strategic Road Network Initial Report, December 2017,


Highways England, Connecting the Country Planning for the long term, December 2017,


Highways England, Sustainable development strategy: Our approach, April 2017,


Highways England, Climate Adaptation Risk Assessment Progress Update 2016, November 2016,


Highways Agency, Climate Change Adaptation Strategy and Framework, November 2009,  


May 2018