A jack-knifed lorry and a diesel spill have been cleared on the A27.
The incident, which happened eastbound by Eastern Road slip, had blocked lanes one and two eastbound.
Police and firefighters attended and are clearing a large diesel spill.
Highways England said the clean-up finished around 3.30pm.
A message on Twitter said: ‘Thanks to contractors who have been working hard to treat diesel spillage during the last hour... all work complete. #A27 eastbound within the #A2030 junction near #Farlington #Cosham is now fully OPEN... .. traffic congestion starting to ease approaching from the #’M27 and #M275.’
Traffic had tailed back to Junction 11 of the M27, with drivers told to expect considerable delays.
A Hampshire police spokesman said: ‘It’s a report of a lorry jack-knifed on the A27, it’s by the Farlington turn off.
‘We got this at 11.54am.
‘The lorry is blocking lanes on and two but there’s a third lane there which traffic is getting through.
‘We are there with colleagues from fire.’
He confirmed there were no injuries reported.
Police are appealing for anyone with information on the cause of the incident to get in touch by calling 101 referring to incident 319 of today’s date.