Rush-hour traffic was at a standstill on the Tuggeranong Parkway on Friday morning after two cars collided, one catching fire.
At one stage, traffic near the Arboretum was static and backed up in both directions as far as the eye could see.
It's the fourth serious hold-up this week as the Canberran rush to work gathers pace after the holidays.
Police said the crashed cars had been cleared from the road about 9.40am, and all lanes were open again.
In one incident on Wednesday, multiple tailgating led to four cars smashing into the one in front after the fifth at the head of the line stopped near Sandford Street.
In Wednesday's other crash, two cars collided also on the Tuggeranong Parkway.
On Tuesday, three people were taken to hospital after a head-on crash between a truck and a car on Pialligo Avenue between the airport and Queanbeyan. Two of the victims had to be freed from their vehicles on the notorious crash blackspot.
Police repeated their frequent plea to motorists to drive according to the road conditions - in other words, not to tailgate or drive too fast in heavy traffic.
"Drivers should maintain a safe distance between their car and the vehicle in front," a spokesperson said.
Police have been worried about the rising toll bad driving takes on the ACT.
In January, a man in his 20s died when the car he was driving crossed into the path of a truck. The rush-hour crash occurred on William Hovell Drive.
As the police reported this first fatality of the year, they said that 2022 was a "horrific" year for deaths on ACT roads.
Acting Inspector Travis Mills said it was "regrettable" that this year's first road death continued a pattern from the previous year.
"The message is consistent - slow down, drive to the conditions, do not be distracted while operating a motor vehicle and, quite honestly, think of your family and arrive at your destination safely," he said.
