The Dutch ‘simultaneous green’ junction arrangements allow people walking and cycling to progress through signal controlled junctions in any direction they choose, at the same time as people from all the other arms of the junction.
‘Simultaneous green’ works well on very large junctions, as this David Hembrow video shows –
As well as on smaller ones. My video this time –
In Britain, however, there is some confusion about whether these kinds of arrangements would be legal, particularly as they involve ‘conflicting greens’ – green signals running at the same time on arms of a junction that are an angle to each other. (See this thread on the Cycling Embassy forum, for example).
Now of course we already have examples of ‘conflicting greens’ in the UK – greens for traffic from opposite arms of a junction, which allow people to turn right across the opposing traffic stream. For instance, if I’m turning right in my car, or on my bike, I have a green signal to go, while someone heading straight through the junction from the opposite direction also has a green. We both have a green, yet our paths will cross! The answer is – the turning party yields, rather than assuming green means a manoeuvre can be performed without conflict.
So this seems to be a straightforward objection to the ‘we don’t do conflicting greens in the UK’ claim.
But what about greens from junction arms that are not directly facing each other? What about you having a green to go straight ahead, while the junction to your left – at 90° to your junction – also has a green?
I was told last year by a highway engineer, whose opinion I value, that there isn’t actually anything in UK traffic regulations that specifically rules out doing this. He explained that this option is technically available. You could give motor traffic green signals simultaneously on two arms of a junction at 90° to each other. This just doesn’t happen because, well, it doesn’t make a lot of sense, and would probably be quite unsafe – for motor traffic, at least.
There is now a new junction in Oxford that seems to substantiate this – that you can allow ‘conflicting greens’ on a junction, at 90° to each other (or indeed at other angles). The Hythe Bridge Street junction lies between the city’s station, and the city centre. It used to be composed of two separate roads, with a cut-though in the middle diagonal for walking and cycling –
The odd arrangement is on the western arm of the junction.
The signals tells us that all motor traffic must turn left, heading north. Meanwhile, however, people cycling are exempted from that instruction – they are able to cycle off in any direction they please, north, east, or south.
So far so good, but allowing people cycling to do this actually involves a ‘conflicting green’. While this arm of the junction is green, it turns out that traffic flowing south out of the northern arm also has a green signal.
Here’s another photograph, this one from Graham Smith, showing the same location, but from the south-western corner of the junction.
The man on the bike and the van driver both have a green signal. Note that at the time Graham’s picture was taken – January this year – there aren’t any road markings in the junction. Indeed, this was the initial plan, as below.
This is, of course, still far from brilliant – if you are not familiar with the junction, it’s not entirely clear how it will work, and even if you are, you are still exposed to collision risk from motor traffic turning around you, without any protection.
But the main point of this post is that – regardless of the safety implications – it is apparently entirely legal to give green signals, simultaneously, from junctions at 90° to each other, as shown below – even if the ‘traffic’ coming from the western arm is cycle-only.
The safety implications of this odd arrangement in Oxford – which involves interactions between bikes and motor traffic – are surely much greater than a clearly-explained simultaneous green layout, which will involve interactions only between people cycling.
So – what’s stopping us?