If an incident results in the need to close all lanes of the F3 in one direction and has the potential to keep the road closed for at least two hours, a contra flow may be used to divert traffic onto the other carriageway.
Traffic will be diverted around an incident site and then back on to the original carriageway. This may involve northbound and southbound traffic travelling in opposite directions on the same side of the road.
A contra flow can be up to 10 kilometres in length. For a contra flow to occur Roads and Maritime Services (replacing Roads and Traffic Authority) and emergency services must:
- Merge the affected carriageway from three lanes to two – before the crossover point approaching the incident site.
- Merge the opposing carriageway from three lanes to one (where possible).
- Lay traffic cones and other traffic control devices for the length of the contra flow in order to keep the two directions separate.
The contra flow can only be activated once all traffic control devices are in place.
A reduced speed limit must be used in both directions for the safety of drivers and emergency service workers. There will be extensive delays because of the reduced number of traffic lanes and the reduced speed limit. Roads and Maritime Services (replacing Roads and Traffic Authority) will do its best to minimise these and any inconvenience to motorists.
When contra flow won’t be used
There are instances where a contra flow would not be an acceptable option for managing traffic around an incident. These include incidents that:
- Do not close the entire carriageway.
- Are unlikely to close the carriageway for more than two hours, such as crashes with no or only minor injuries for those involved.
- Occur during a period of low traffic volumes (late at night). Motorists will be detoured.
- Occur in the opposite direction to the peak flow of traffic. This is because a contra flow reduces the number of lanes for that side of the F3, which would cause even more delays for heavy traffic travelling in the opposite direction.
Contra flow on the F3
Click on the image (left) to watch the F3 contra flow video. (duration: 4 minutes, file size: 16.4MB).
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