Eight people have been taken to hospital after a multi-vehicle pile-up in the main tunnel of Sydney's Eastern Distributor.
The accident led to a two hour closure of the Eastern Distributor and Harbour Tunnel, compounding long weekend traffic problems.
The Roads and Traffic Authority said the accident site had been cleared and all lanes were open to traffic, but the tunnel remained congested and motorists should allow extra travel time.
Five adults and three children were among 14 people assessed by paramedics following a collision between six cars and a truck which sparked traffic delays from around 11am (AEST) today.
They suffered minor injuries and were taken to St Vincent's, Royal Prince Alfred and Royal North Shore Hospitals.
All were in a stable conditions, the NSW Ambulance Service said.
The incident caused the closure of the Sydney Harbour Tunnel's southbound lanes and at one point traffic banked up to Artarmon on the Gore Hill Freeway.
Meanwhile, flights at Sydney airport have been delayed by up to 50 minutes today, following a shortage of air traffic controllers.
A chronic staffing shortage at Airservices Australia this morning saw two of the regular team of six controllers call in sick.
"We have had to reduce the operation's of our Sydney offices as a result of staff absences," an Airservices spokesman told Fairfax.
"We've now cleared the backlog of flights and expect that the flights will be able to return to the normal schedule this afternoon."
The number of departures from the international and domestic terminals was drastically reduced as a result and follows a similar incident in April.
The M5 Motorway has also been recently reopened after an accident near Botany this afternoon.
The incident came two weeks after the second shutdown in three months of Sydney's M5 East tunnel.
A suspected computer failure on September 22 closed the southern Sydney tunnel for three hours, at a time when an average 8,000 motorists an hour used the motorway.
That closure followed an almost five-hour shutdown prompted by another computer glitch on June 25.