Two lanes are closed on the M4 after a crash involving at least six cars and a lorry.
It's between J19 (Bristol) and J20 (the Almondsbury Interchange) and is affecting traffic back to J18.
Normal traffic conditions aren't expected to resume until at least 16:45.
A full police investigation is underway after an accident on the M4 Eastbound this morning (7 June)
A single car was involved from around 3am between J19 (Bristol) and J18 (Bath).
Two lanes are closed and a speed restriction of 50mph is in place while police investigate.
There's been an accident on the M4 Eastbound between the Almondsbiry Interchange and Bristol.
It's affecting traffic between J20 and J19 as drivers slow down around the scene.
A stretch of the M4 near Bristol has recorded some of the fastest speeding motorists in the region.
A Freedom of Information request shows that four drivers were found to be travelling at more than 130 miles per hour between the M32 and the Almondsbury interchange (J20 - J19).
The top speed recorded was 144mph - almost double the 70mph speed limit.
Dorset Police have also reported some high-speed drivers. One incident on the A35 Puddletown Bypass saw a driver reach a limit of 118 mph.
Even more worryingly, the county also reported three drivers who were speeding at more than 75 mph in 30 mph zones.
One lane is closed due to flooding on the M4 Westbound between J16 (Swindon West) and J17 (Chippenham).
Drivers are urged to take extra care today as surface water and heavy rain could make conditions dangerous.
Two lanes are closed and traffic is slow due to a vehicle fire on the M4 Westbound between J18 (Bath) and J19 (Bristol).
Drivers are advised to approach with care. Lanes one and two are closed and there's the possibility of smoke blowing across the carriageway causing low visibility.
A Romanian man is critically ill after his articulated lorry overturned into a ditch on the M4 near Bristol this morning, 25 September.
The lorry was travelling Westbound along the Almondsbury interchange when it overturned at 6.30am.
The driver, a 28-year-old Romanian national, was taken to Southmead Hospital in Bristol with serious injuries and is in a critical condition.
Police would like to hear from anyone who saw what happened.
The westbound stretch of the M4 has been closed between junction 21 and 22 all day to allow for the scene to be examined and for the lorry can be recovered.
There are long delays on the M4 westbound near Bristol. It was caused by a lorry that overturned between J21 for the M48 and J22 for the M49 at 6.30am this morning. There is congestion right back to J18 for Bath.
Police say removing the overturned lorry has proved to be a "significant challenge". The operation is ongoing.
Meanwhile the Highways Agency is advising motorists to divert via the M48 towards Wales using the original Severn Bridge, although this is also very congested as a result of the extra traffic from the closure.
The M4 is closed westbound between Junction 21 (M48) and Junction 22 (M49). It is due to accident investigation and recovery work after a lorry overturned at 6.30am.
It is causing major congestion back to the M32.
Drivers are being advised to divert via the M48 towards Wales using the old Severn Bridge but be warned the closure is having a knock on effect and there are heavy queues at the Toll Booths.
Two cars have been involved in an accident on the M4 Eastbound between J20 (Almondsbury Interchange) and J19 (Bristol).
One lane is closed and traffic is slow.