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
M4 relief road Cardiff University called for the decision to cancel the road to be overturned. In December 2011, the UK Chancellor of the Exchequer, George Osborne, announced that he would discuss options for improvements to the M4 with the Welsh Government, including the provision of additional finance which, it has been reported, could lead to the re-emergence of plans for a new M4 relief road. In February 2012 work started on a dual-carriageway road connecting Newport's southern distributor road to junction 23A of the M4 using part of the proposed route of the M4 relief road and a former access road to