M4 motorway not signed, European route E30 includes most of the M4. The M4 has two sections of smart motorway. The one between junctions 19 (M32) and 20 (M5) north of Bristol has variable speed limits and a part-time hard-shoulder. Completion was in summer 2014. The section between junctions 24 and 29 in Newport has variable speed limits. In 2010 it was announced that a smart motorway would be constructed between junctions 3 and 12, with work starting in Autumn 2018. This will be the longest smart motorway scheme in the United Kingdom, with a length of 51km (32 miles). Work is
M32 motorway opened by the Secretary of State for Transport, John Peyton in July 1970. The total cost was £3 million (now £ million). In 1972, a polystyrene storage depot on Muller Road near junction 2 caught fire, leading to the closure of the southbound M32 for six days. The third section was the most technically demanding, as it ran through heavily built-up urban areas and required numerous properties to be demolished, along with the "Thirteen-arch viaduct" near Stapleton Road that was built in 1874. Work was delayed owing to the Three-Day Week industrial action in 1974, and further because of a