DRIVERS using the M4 on Monday night (February 13) are being warned that the westbound exit slip road at Junction 16, between Swindon and Royal Wootton Bassett, will be closed overnight from 8pm until 6am on Tuesday (February 14), as part of the traffic management and roundabout rebuild currently taking place. Drivers can either leave the motorway at Junction 17 on the west side of Swindon or carry on to Junction 18 near Chippenham. Diversions will be clearly signposted.