Last September TfL announced the rollout of Green Man Authority at 20 pedestrian crossings across the capital. This is radical stuff, essentially switching priority from road users to pedestrians.
Green Man Authority
Traffic signals show a green signal for pedestrians continuously until vehicular traffic is detected, at which time the pedestrians are stopped on a red signal and vehicles are given a green light to proceed.
Normally at a stand-alone crossing the default is to show a green light to traffic with the pedestrian phase only kicking off if a button is pressed. Under Green Man Authority the system is reversed and the lights favour pedestrians until a vehicle turns up. It works best where pedestrian flows are busier than the traffic, or at times of day when traffic flow is light. At busier times you'd not notice any difference compared to normal because GMA only kicks in when there are gaps in traffic.
• A green man is shown to pedestrians for as long as the signals do not detect an approaching vehicle.
• If an approaching vehicle is detected, the signals show a red man to anyone who has not yet begun crossing.
• The vehicle is then shown a green signal.
• Once it has passed, a red light is shown to traffic and a green man to pedestrians.
Green Man Authority has been trialled in a handful of places before, notably on the pedestrian crossing between Westfield and the Olympic Park in Stratford. I was excited to see that one of the new 20 was going to be near me, on Devons Road immediately opposite the DLR station, but back in September absolutely nothing seemed to change. It didn't change for the next eight months either until suddenly, this May, the lights suddenly started favouring pedestrians.
And it feels very odd. As if by magic, with nobody pressing any buttons whatsoever, the traffic lights switch from green to red and pedestrians are invited to cross instead. It doesn't matter that there aren't any pedestrians, only that there might be.
Unexpectedly it seems that the Devons Road crossing isn't following proper Green Man Authority rules because it never sticks permanently in the green man phase during a gap in traffic. Instead the green man shows for the normal six seconds, then the countdown starts and then the non-existent traffic gets the green light again. And this cycle repeats, as if an unseen finger keeps on pressing the button, until either a vehicle or a pedestrian turns up.
I watched for five minutes and only one pedestrian turned up wanting to cross the road, but during that time the lights changed from green to red and back again an astonishing nine times. Considerably more cars were disadvantaged by the endless switching of the lights, but that was their bad luck for turning up outside a prolonged line of traffic.
Shortly afterwards a bunch of pedestrians turned up when the traffic was fairly relentless. In this situation pedestrians didn't get priority, they still had to wait while the cars went by and eventually the lights changed in their favour after the usual time interval.
I also watched to see how far away the traffic had to be before it triggered the signals. The Devons Road crossing is awkwardly placed with a bend in the road on one side and a mini-roundabout on the other, and the sensors often missed approaching vehicles until they were almost on top of the crossing. Had the lights changed quicker these vehicles might not have been forced to stop but instead they got to brake for the benefit of nobody crossing whatsoever. Let's just say the system could be further nuanced.
I know how Green Man Authority is supposed to work because I found an official TfL report on it. I discovered that one of GMA's aims is to improve pedestrian compliance with signals, because when there's no traffic they tend to cross the road anyway. I noted that the intent is to be beneficial to pedestrians and of only marginal impact to road users. I learnt the word 'intergreen', which is the period of time between the end of a green light phase for drivers and the beginning of the green light phase for pedestrians. And I found this table which demonstrates the traffic control strategy, i.e. what triggers a switch from Stage 1 (traffic passing) to stage 2 (pedestrians crossing).
It looks complicated because the system has to allow for minimum times so that lights don't change ridiculously frequently. But in essence it says let pedestrians cross unless there aren't any and there is some traffic.
The report also addresses the issue of Audible Functionality. Pedestrian crossings are meant to beep while the green man is showing, and if you prolong that phase it could lead to "potential intolerable noise pollution". I once lived in a bedsit immediately adjacent to a pedestrian crossing and if anyone had ever fixed that to be predominantly green I doubt I'd ever have got any sleep. The solution is to restrict the beeping to the normal six seconds and only turn it back on again if anyone presses the button, which of course a blind user would be expected to do.
In the meantime the Devons Road crossing continues to behave unexpectedly, both compared to the norm and compared to how other GMA signals work. Perhaps the repeated flipping is part of a deliberate trial, or perhaps technicians couldn't refine the sensors properly, but at present pedestrians are only being prioritised some of the time there's no traffic. Whatever, if your local stand-alone pedestrian crossing starts behaving oddly and disregarding drivers, it might be that Green Man Authority has kicked in.
