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 Western Motorway get to Parramatta without passing through traffic lights. A subsequent plan outlined a $7 billion plan to link the M4, Victoria Road, City West Link and Sydney Airport using a network of underground tunnels.. Both plans were subsequently shelved, with the NSW state government citing the need for an integrated plan for transport. In the month prior to the 2011 state election, the NRMA released a report in which it recommended building a tunnel to connect the end of the M4 at Concord and the start of the City West Link, relieving Parramatta Road of enough traffic to convert it