Today02:09 BSTHeathrow T1 diversion route Heathrow T1-4 traffic:At J3 exit the M4 and take the 1st exit on to the A312 'The Parkway'.At 'Waggoner's roundabout take the 3rd exit onto the A4 'Bath Road'.At the A408/Nene Road turn left and exit the A4.At the next roundabout take the 3rd exit onto 'East Ramp' the next roundabout is the Heathrow Tunnel roundabout.Today02:08 BSTM4 westbound diversion routeRoad users are advised to follow the hollow diamond signage.M4 westbound traffic:At junction 3 exit the M4 and take the 3rd exit onto the A312 'The Parkway'.Continue following the A312 'The Parkway' through three roundabouts for approx. 4.1 miles.At the fourth roundabout take the second exit and continue on the A312 'Church Road'.At the next roundabout take the 1st exit and join the A40 westbound.Continue on the A40 as it merges into the M40At J1A exit the M40 to access the M25 anti-clockwise J16 to J15.Follow the M25 anti-clockwise to J15 and exit at J15 to access J4B M4.