A car flipped over after being involved in a smash with a tractor along the A41 on Tuesday evening.
It happened close to the Chesham junction, heading towards Hemel Hempstead, at around 6.40pm.
Debris scattered onto the northbound carriageway, which meant rolling roadblocks had to be put in place on both sides of the bypass during the clear-up operation.
On the same evening two cars were involved in a smash on St Albans Road, Hemel Hempstead, close to Lamsey Road.
Both vehicles had to be recovered but nobody was injured.