National Highway Sector Schemes (NHSS) are bespoke integrated quality management systems for organisations working on the National Highways strategic road network, which accounts for approximately 4% of all roads in England. Local Authorities are responsible for the remaining 96% and will often adopt these management schemes. If your company supplies services (including the supply of products but excluding the manufacture of products subject to legal conformity assessment requirements) to National Highways under the Specification for Highways Works (SHW), you MUST be certified under all the relevant schemes for the work you carry out.