The M3 spans across the south-west of the country and connects Sunbury-on-Thames in Surrey to Southampton, in Hampshire. Stretching 59 miles in length, the M3 is one of the main commuter routes in and out of the capital. Heading south-west along the M3 you have direct access to the A31, which flows down to Southampton and Bournemouth.
The first stages of construction on the M3 began in 1971. It took 24 years to complete and opened to road users in 1995. During the late stages of completion, there was controversy surrounding the historic St Catherine’s Hill fort, which stood in the initial M3 route plans. After many debates, it was decided to cut through the nearby countryside south-east of the monument to avoid destroying it.
The M3 flows past Winchester, Basingstoke, Farnborough and Chertsey, leading into the M27 at the southern end.
As this road is a popular commuter route in the south-west of England - and can get very busy during peak hours - so it’s important to check for any M3 traffic updates before you leave for your journey.
Worst Junctions on the M3
Along the M3 there are several black spots you should consider when planning your route. Before you set off, make sure you factor in time for unexpected delays and check for road updates and M3 travel news via the RAC Route Planner app. The following junctions are common hotspots to be mindful of:
Two small double roundabouts close together means that there’s a general build-up of traffic, both southbound and northbound and on the A335 heading towards Allbrook.
Junction 10 - Chilcomb Interchange
Where the A31 meets the M3, the heavy traffic from Southampton can cause congestion. There are two roundabouts to navigate around on the A31 and it can also be confusing to navigate.
The junction that connects the M25 at junction 12 and the M3 at junction 2 can be a tricky spot. With heavy traffic and lanes to navigate as the routes split it’s important to be alert and plot your route early.
This interchange near Lightwater can get congested due to road users making their connection into West London from the M4 down the A322.
Accident Hotspots on the M3
Expect a build-up of traffic on the 2.8-mile connection between junction 11 and 12 due to several routes flowing from Winchester, Otterbourne and the surrounding towns. With the added traffic, take extra care during peak travel times.
The stretch between junctions 2 and 3 - with two tricky junctions to tackle, set only a few miles apart - is considered an accident blackspot.
Junction 9 is a major link to the A34 near Winchester. With large amounts of fast-moving traffic, accidents are common.
Upcoming M3 Major Roadworks
Do make sure you check for roadworks and delays along your journey before you depart. You can do this by using the RAC Route Planner for M3 traffic news and updates that will help you plan ahead and reduce delays.
Upcoming major roadworks on the M3 include:
Between junctions 9 to 14: This major scheme is set to improve conditions by upgrading to a smart motorway between the Winchester A34 interchange and the M27 Southampton junction. Work should start in 2019/2020.
Junction 9: Work is set to start in 2021 to improve congestion and delays when approaching the junction, making room for free movement between the M3 and A34.