taxis queuing in a bicycle lane under no stopping signs

Red Light Special

Children have the concept of traffic lights instilled from an early age aided by the complete simplicity of just two states, each with a single instruction: Green = Go, Red = Stop. But somewhere along the way and with a creeping me too mentality, all that falls apart.

The first example shows a signal transition against light (free flow) traffic as the staggered drivers react to their relative positions.

Deceleration in the camera vehicle is gentle and pulls neatly to a stop just ahead of the red light, and the champagne coloured hatchback is in the intermediate situation of being able to stop but feels they don’t fit the legal definition required:

57 Stopping for a yellow traffic light or arrow
(1) A driver approaching or at traffic lights showing a yellow traffic light must stop
(a) if there is a stop line at or near the traffic lights and the driver can stop safely before reaching the stop line

“Safely” being open to wide interpretation. Currently the fine for infringing this rule is $758.35 (5 penalty units) although you rarely hear about its enforcement in the state of Victoria. Once stopped the much more impatient driver continues through the intersection against the red light over 1 second after it has already turned red. Having spent several weeks counting such events travelling across thousands of intersections (they add up quickly) vehicles in Melbourne are running through solid red lights as above at approximately 1% of all vehicles at each traffic light, ignoring all the close cases and examples where it was not clear and just counting these extreme examples the figure is depressingly high. Considering a typical journey includes many intersections with many vehicles at each, at 1% of all vehicle-light interactions it becomes routine to see vehicles passing red lights on most journeys.

Vicroads have been trimming all the safety margins out of their traffic light phasing; but in these examples unencumbered motor vehicles are simply ignoring the lights and ploughing on through. Here only entering the intersection as the opposing traffic receives their green light:

56 Stopping for a red traffic light or arrow
(1) A driver approaching or at traffic lights showing a red traffic light must stop
(a) if there is a stop line at or near the traffic lights—as near as practicable to, but before reaching, the stop line

With $1516.70 (10 penalty units) on the line for failing to stop at a red light the onus would be on the driver to prove Vicroads had provided an inadequate length yellow phase, which can easily be checked. Although usually provided in tabulated form the exact requirement can be determined from the Australian Guide to Traffic Management Part 9:

Yellow Time = max[ 3 seconds or (reaction time 1 second) + 0.5*((design speed km/h)/3.6)/((declaration rate 3 m/s²) + 9.8*(average gradient fraction)) ]

There are several variations which may be used to increase the above yellow time, but it will not be less than this. Calculating for a flat road at 60km/h (37 mph) would produce a yellow period of 3.8 seconds, which if you’ll count the timing of the first example above at 4.0 seconds, sufficient time provided for the driver to stop safely. Looking around Melbourne we can find examples where there the period is deficient:

Here the yellow phase is obscured but could not have been displayed for longer than 4 seconds, which for the uphill grade of the loaded trucks pulling away from stopped is inadequate and the design speed needs to account for their capabilities (this is an access road to the docks and is almost exclusively used by heavy trucks). But the car entering 2 seconds after the red would still be left without an excuse. The scant few automated infringement cameras around Melbourne are both well known in their locations and extremely lax in enforcing the above rules, along with police who can routinely be seen watching traffic running red lights yet choose to do nothing about it.

Dangerous as these manoeuvres are they cascade (along with vehicles blocking intersections) into the situation present in Melbourne where the vehicles entering the intersection do not rely on the traffic lights but instead visually check before proceeding. This propagates through the queue and each vehicle in turn waits for the vehicle in front to move before proceeding. Compare to the behaviour in other cities where the queue of vehicles will all start to move off once the light turns green knowing with confidence that the intersection will be clear. Congestion is able to be relieved by simply enforcing the road rules, a step too far in Melbourne.


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