Intersection - Turn Lanes (Signalised)

Signalised intersections with fully controlled cross-traffic light phases indicate to drivers when to enter the intersection, thus removing the problem for them of selecting safe gaps in the traffic flow. This reduces crashes between turning vehicles and oncoming through traffic.

Signalised turn lanes can also be helpful where there is a history of crashes between turning vehicles and pedestrians crossing the road. Signalised turn lanes are created by installing additional display lanterns facing the chosen approach; red, yellow and green lanterns for the through movements and for example, red, yellow and green turn arrows. Dedicated turn lanes should be provided if they don't already exist at the site.

Further information on signalised intersections can be found on the Intersection - signalise page.

A signalised turn lane may be installed for any of the following reasons

  • new traffic signals are being installed
  • there is a history of crashes between turning vehicles and oncoming through traffic
  • there are two or more lanes that turn across traffic
  • turning traffic is opposed by two or more through lanes of traffic
  • two or more opposing through traffic lanes have high operating speeds
  • sight distance to the intersection is limited.

    • Reduced crashes between turning vehicles and oncoming through traffic.
    • Reduced severity of crashes throughout the intersection.
    • Reduced vehicle-pedestrian crashes.
    • Adding turn signals reduces intersection capacity.
    • It may be necessary to lengthen turn lanes to fit longer traffic queues.
    • Other signal changes can be used to improve intersection capacity when signalised turns are implemented.

    Benefits

    • Reduced crashes between turning vehicles and oncoming through traffic.
    • Reduced severity of crashes throughout the intersection.
    • Reduced vehicle-pedestrian crashes.

    Implementation issues

    • Adding turn signals reduces intersection capacity.
    • It may be necessary to lengthen turn lanes to fit longer traffic queues.
    • Other signal changes can be used to improve intersection capacity when signalised turns are implemented.

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    Treatment Summary

    Costs
    Low to medium
    Treatment life
    5 years - 10 years
    Effectiveness
    10-25%

    References