The M3 is the road south-west from London, serving the densely populated towns in the west of Surrey, the north of Hampshire and the south of Berkshire. It's not especially long as major inter-urban motorways go, but it certainly isn't quiet, and it's had more than its share of controversy.
M3 J9-14 Smart Motorway 6 March 2018
Upgrade of the M3 between junction 9 (the A34 at Winchester) and junction 14 (the A33 and M27 north of Southamnpton) to Smart Motorway standard. This part of the M3 suffers particularly high levels of traffic, being a single link connecting the major conurbation and port at Southampton to the wider UK.
M3 J2-4A Managed Motorway 19 May 2017
Upgrade of the existing M3 between junctions 2 and 4a to allow dynamic hard shoulder running (use of the hard shoulder as an extra lane at peak times). Where necessary, junction capacity will be increased to prevent traffic queues building up on the slip roads and encroaching on the main carriageway.
This scheme was introduced as part of the National Infrastructure Plan in autumn 2011.