Motorway cantilever sign
A blue overhead sign suspended over the motorway from a post on the left, with a downward-pointing arrow indicating the left-hand lane, and the following text.
A4 [Hollow triangle diversion symbol] [Hollow square diversion symbol] [Hollow diamond diversion symbol] ; Langley; Colnbrook; B470 ; Eton; Datchet.
Junction number: 5.
This junction serves the eastern end of Slough and some nearby towns, and is our last calling point before we hit the M25. Squeezing all the M4's traffic into three lanes is a bit of a tall order at this point and, despite all the Smart Motorway widening, there can still be delays here.