There are reports queuing on the M4 near Slough following a lorry being involved in a collision and overturning.
Highways England has advised that overturned HGV has shed its load of gravel on a live traffic lane.
The incident is in the M4 westbound between J7 (Slough (W) / High Wycombe) and J8.
There is one of three lanes closed.
Drivers are being advised to avoid the area.
Officers from Thames Valley police have taken the decision to close the Westbound EXIT slip on the #M4, traffic officers are currently on the closure.
The closure is likely to be in place for some time