Coming to a motorway near Heathrow, the M4 is to be re modelled as a smart motorway starting shortly, from outside Maidenhead to the two lane carriageway at the elevated section, ie four lanes of volume into two. The work will take 54 months which is quicker media speak than 4.5 years. Traffic will be diverted onto the A4 which will also be moved for construction of R3 at the same time as as the M25 alteration. Please bring extra fuel,food and boredom in the resulting traffic chaos.��