There was heavy rush-hour traffic due to the closure of the A41 Aston Clinton Bypass after a van carrying gas cylinders caught fire.
Just before midnight, the van caught fire and three fire crews were quickly on the scene.
They set up a 200 metre cordon while they tackled the blaze. A man was left in the care of paramedics.
It meant the bypass was shut in both directions between the A41/Icknield Way (Crows Nest Roundabout) and the A41/London Road (Woodlands Roundabout).
The acetylene cylinders may need to be left to cool down for up to 24 hours but closures have now been lifted and the road is open in both directions.