FLEXIBLE work hours leading to more parents picking up children from school have created an extra peak hour on Australian roads.
Transport Department data shows increasing volumes of traffic are hitting arterial roads out of the city by 3.30pm.
In 2009, an average of more than 400 vehicles entered the average capital city intersection in the 15 minutes to 3.30pm, compared with about 150 in 2002. Traffic peaked with 550 vehicles in the 15 minutes to 5.30pm in 2009.
While school pick-up runs are not new, it is believed more people opting to start and finish work early, a rise in shift workers, growing car ownership and the now common practice of chauffeuring children to school are contributing to the changing traffic patterns.
Transport Department spokeswoman Bobbie-Jean Stevens said there were numerous other examples of "peak spreading" throughout Australia's road network and put the phenomenon down to an increasing tendency for children to be picked up from school and greater flexibility in travel times due to working arrangements.
"Together with an increased motor vehicle ownership per head of population over time, there is now greater opportunity for people to travel in the late afternoon," she said.
While more drivers are leaving work earlier, many arterial roads are moving slower during peak times,
according to Transport Department time travel data. Another contributing factor not mentioned by the department is the reduction of many car lanes across Sydney, Melbourne and Brisbane to make way for paid bus transit lanes, and cyclist lanes.
Transport department data shows peak spreading is not as prevalent in the morning.