Traffic on the M25 in Hertfordshire was beginning to return to normal on Wednesday afternoon after a fire closed the motorway for almost a day.
The van sits on the hard shoulder of the M25
The fire, on Tuesday afternoon, burned out a van transporting an acetylene gas cylinder between junctions 22 and 21A south of St Albans.
A fire service spokesman said the van had been judged safe by mid-morning.
The clockwise carriageway reopened by lunchtime and the anti-clockwise route by 1500 BST.
The van was removed from the scene.
The shutdown, to create an exclusion zone round the van, meant long tailbacks for traffic on the M25 with queues back past Potters Bar.
The disruption also affected traffic joining from the M11, the M1 and the A1M.
Emergency services were called to the van fire south of St Albans on the anti-clockwise carriageway at 1540 BST on Tuesday.
The fire was dealt with swiftly and no-one was injured but officers set up an exclusion zone round the scene when they realised the vehicle was transporting the potentially explosive cylinders.
The police spokesman said under fire service and health and safety regulations acetylene gas must remain undisturbed and monitored for 24 hours after a fire.