The cure for creeping: four-state traffic lights

Since moving to Dublin, I’ve noticed a phenomenon that I don’t remember seeing in the north, and is rare even in Galway. At traffic lights, the first car in the queue will regularly start moving forwards long before the lights turn green. In extreme cases, presumably because the driver has misremembered the order of the phases, this can result in a car being left stranded in the middle of the junction while traffic from another direction attempts to negotiate around it.

I’m convinced (albeit unscientifically) that this results from the combination of two main factors: the desire, particularly common in cities, to be prompt in clearing the junction; and the lack of advance notice that a three-state traffic light provides. This results in a hair-trigger disposition in many drivers and a high rate of premature action.

To clarify, a three-state traffic light goes from green to amber to red on stop, but straight from red to green on start. This system is used in France, the US and the RoI (amongst others). The amber “prepare to stop” light is necessary to avoid a sudden change from green to red, which could obviously result in driver panic and serious accidents, but no similar facility exists going from red to green.

A four-state light, as found in the UK and Germany, adds a red+amber “prepare to go” state between red and green so that drivers do not need to remain in a prolonged state of readiness. This is useful for any vehicle that takes time to put into gear, or has a handbrake, or whose driver’s mind is likely to wander.

If the RoI were to introduce this fourth state into its traffic lights, I’m confident the incidence of creeping through red could be significantly reduced. And since all our new traffic lights are made in Germany by Siemens, the change is likely nothing more than a setting in the software, so could be introduced at minimal cost.


5 thoughts on “The cure for creeping: four-state traffic lights”

  1. You’re obviously not paying much attention. I see this behaviour daily in Belfast with cars edging across stop lines, especially where ASLs are provided. The most significant factor is drivers failing to stop fully, hanging on the clutch and pre-emptIng the change from red to amber.

      1. Observation bias? Your opinion influences the outcome of your research.
        Only way to test your hypothesis is to select two similar junctions either side of the border, with similar layout, traffic flow and demographic in surrounding area and record stop line offences over a set amount of time.

Leave a Reply

Please log in using one of these methods to post your comment: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s