The A41 had to be closed for more than two hours last night after a smash involving a 4X4 and caravan.
Police were called to the bypass just before 8pm last night.
The busy road had been completely blocked by the collision, which happened about a mile before the Tring junction heading towards Aylesbury.
Officers closed the carriageway and diverted traffic through Berkhamsted and highway engineers were called in to help clear the debris.
The caravan, which was being towed, is understood to have been completely destroyed by the impact with a black Mitsubishi Shogun.
Police were able to briefly re-open one lane of the bypass at 8.15pm but it had to be closed again while vehicles were recovered.
The road was completely re-opened at 11.15pm.