Efficiency versus consistency

Here’s a real world example of where consistency can matter more than efficiency: The traffic light controlled intersection at Haydon Drive and Jaeger Circuit.

Because there’s only a single lane coming out of Jaeger Circuit onto Haydon Drive southbound and because of ACT road rules, vehicles must stay in that right lane, so technically traffic in the left lane of Haydon Drives southbound shouldn’t need to stop at this intersection. But for consistency and to reduce confusion, all traffic is brought to a stop when cars on Jaeger Circuit have a green light.

Map of traffic light controlled intersection in Bruce, Canberra

To increase efficiency, the intersection would need substantial modifications to ensure signals are clearly comprehended by drivers and installing barriers as has been done at the south end of Anzac Parade for the left lane of northbound Parkes Way traffic. Also the Wentworth Avenue – Canberra Avenue – Sturt Avenue roundabout in Fyshwick where southbound traffic from Wentworth can safely bypass the roundabout onto Canberra Ave.

A poorly-designed example is the Yarra Glen – Yamba Drive – Melrose Drive roundabout in Woden where there is an increased risk of collisions because those same structural measures haven’t been implemented other than a solid white line, further compounded by the physical layout where vehicles on Yarra Glen are essentially going straight ahead onto Yamba.

Imagery © 2017 CNES / Astrium, DigitalGlobe, Map data © 2017 Google

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