Motoring groups are calling for better information and help for road users after thousands of motorists were trapped on the M3 in Hampshire yesterday.
Some were stranded for up to 12 hours while bomb disposal experts tackled a mysterious hazard on the carriageway.
Police said a bomb disposal team had been at the scene of the closure between junctions nine and 11 at Winchester.
The motorway was closed in both directions from about 4am but fully reopened at about 3.30pm
Hampshire Constabulary said officers were working with fire crews and the Ministry of Defence's Explosive Ordnance Disposal team to establish what the material on the road was.
As of Sunday morning they have not given any further details.
The gridlock has prompted anger from Transport Focus, who say more could have been done to limit the disruption:
Highways England, the local authority and the police have a duty of care to trapped road users.
Dozens of roads around the M3 were also gridlocked as drivers tried to circumvent the queues.
Robin Britton took this footage of cars struggling to pass each other on country lanes:
Many people took to social media to vent their frustration while others made the most of a bad situation: