Hundreds of motorists were left fuming after the gates to a park-and-ride car park were locked.
Some drivers queued on the A4 Portway in Bristol for more than two hours from 0600 GMT near the Avonmouth site.
A council spokeswoman said: "The council apologises for the park-and-ride at Avonmouth not being open on time this morning."
She said two people from a contract firm had each thought the other was due to open up the car park.
Many motorists gave up waiting and parked their vehicles along the Portway and in residential areas.
They were then able to catch the bus which stopped to pick up passengers opposite the car park.
The spokeswoman said: "That option wasn't available for everybody and for that we sincerely apologise. It certainly was not our finest hour.
"What's of concern to us is that we need to put a report mechanism in place to make sure it never happens again."
She said the gates were finally opened at about 0800 GMT after a manager battled through rush-hour traffic to get to the site.