The M4 is closed in both directions between Junction 4 and Junction 3 in Greater London. Police lead the response and have shut the carriageway to allow emergency work at the scene. National Highways resources support this operation.
Two junctions, two directions, one complex closure
Describing the affected stretch as between J4 and J3 sounds straightforward. In reality, closing a motorway in both directions creates a large-scale operational challenge. Traffic must be prevented from entering the section, while those already on the route must be managed safely. The road becomes a protected, controlled space rather than a transport corridor.
How the closure works in practice
At incidents like this, police take priority. They decide when the carriageway is clear for responders to work safely. National Highways provides resources to support the police-led response on the strategic road network.
Closing the motorway is not just about stopping vehicles and waiting. The carriageway must be secured to protect people working at the scene and maintain control over access. This requires clear coordination across multiple teams and the physical closure of entry points at both ends of the affected section.
Impact on the network and drivers
For drivers, the closure means a key route they expected to use is unavailable in both directions. Alternative routes must be found while the carriageway remains closed.
For those managing the network, safety comes before speed. The priority is controlling traffic and protecting the scene until work finishes and the road is safe to reopen. This includes coordinating with police and monitoring conditions on the ground.
The handback process can be complex. The motorway only reopens once responders confirm the area is safe. Until then, the carriageway remains closed despite any queues or driver frustration.
What this shows about motorway incidents
This closure highlights how a motorway incident quickly shifts from a transport route to an emergency scene. It illustrates the layered decision-making behind road closures, where police and highway authorities coordinate closely to manage safety and disruption.
The M4 closure between Junction 4 and Junction 3 is an example of how even short motorway sections can require detailed control when incidents happen. It also underlines the visible disruption as just the surface; underneath sits a complex operation prioritising safety over traffic flow.
