Monday, 18 April 2011

Delays at traffic light controlled crossings


Cyclists and pedestrians elsewhere often feel that their time is wasted by pedestrian and cycle crossings which are timed in such a way that they prioritize "keeping traffic moving" over people who want to cross roads. This often causes people to cross against a red light, especially if they are in a hurry.

Here in the Netherlands, timings are quite different. This video shows a crossing on the route to school taken by my youngest daughter. The maximum delay is eight seconds. Therefore she never has to wait too long for a green light and I am happy that she is never tempted to cross while the cars are still moving.

If only it could be like this everywhere...

Comparison with the UK
Some years ago, I did some calculations based on a pedestrian crossing which I used with my daughter on the route which we walked to school in Cambridge. This was a very typical crossing for Britain. Even though the highway engineers can correctly claim that the cycle time is the same for motorists and pedestrians, the average delay for motorists still works out as a far shorter time than that for pedestrians:

Assuming that the junction splits time 50:50 for the two different directions, and that there is a 1 minute cycle time, a motorist can expect to be delayed a maximum of 30 seconds. Half of drivers are not delayed at all as the light is already green, and the other half are delayed by an average of 15 seconds, making an overall average delay of just 7.5 seconds for a driver.

On the other hand, a pedestrian only gets to cross if they walk right up to the crossing and push the button. Typically, the green phase for a pedestrian will last as little as 3 or 4 seconds, fitted into the 1 minute cycle. What's more, there is an initial use delay on the button intended to make pedestrians bunch up. The intention of this is to make best use of the this short time and "keep traffic flowing" on the road in the meantime.

So, you push the button. Wait, say, 10 seconds, then have an average delay of (60-4)/2 = 28s. As a result, the average delay for a pedestrian is 38s. That's 8s longer than the maximum for a driver or 5x as long as the average for a driver even though they are subject to the same cycle time.


Now I know that some people will say "it's just a few seconds", but let me explain further. At one time I would walk my children to primary school, then return, walk again to collect them, and return again, using this crossing four times a day. That means that on average the pointless extra delay would consume one and a half minutes each day. That's about as long as it would have taken to make one of the journeys by car. I literally worked the numbers out while waiting for a green light to show.

Newly built junction in Cambridge,
England. Cyclists and pedestrians on
shared use path must use four crossings
to cross one road.
Other examples in Cambridge were even worse. This junction was built next to a new development near us while we lived in the city. It's a less major junction than the large junction shown in the video above, but it's far less convenient for cyclists or pedestrians. At this junction, drivers have one set of traffic lights to wait for with the timings generously set up for them, average delay of around 7.5 s as worked out previously. However, pedestrians and cyclists on the shared use path had to use up to four (never fewer than three) light controlled crossings just to cross one road. I wrote about it as soon as I saw a copy of the plan. Complaints had no effect. It was implemented exactly as in the plan.

As you'll have seen from today's video, it's really not the same here. Cyclists often get to avoid traffic lights altogether so you see far fewer of them than if you drive. However, when you come to a traffic light it will work well for pedestrians and cyclists and not cause you to feel like a second class citizen due to a ridiculous delay. Almost always the junction will have started counting before the button is pressed because it is normal to have both a loop under the ground and a button at junctions. Sometimes such crossings are even set up so that the light defaults to green for the cyclist.

Peter Miller also wrote about delays at a pedestrian crossing in the UK.

Note that the junction at the top also allows cyclists to take a short-cut which isn't open to drivers. This is an example of how unravelling of driving from cycling routes encourages cycling by making it more convenient than driving.

Of course, some traffic lights in the Netherlands are not so ideal. But I've yet to find one which appears to be set up specifically to annoy pedestrians as sometimes seems the case in the UK. The day after this post, Gaz545 wrote a response which shows "Delays at crossings in the United Kingdom".

16 comments:

Reuben said...

Great post. I wrote about the delay often imposed on cyclists on sidepaths at signalized intersections here.

Paul Martin said...

In Australia these buttons just register that there is a pedestrian or cyclist there (assuming they're connected) so that on the next cycle of the lights you will get a green walk or cycle symbol (for a few seconds...). They do not speed up the next light cycle at all :(


This sort of infrastructure shows that The Netherlands respects both pedestrians & cyclists. Here it is all about the car... with little respect for any other means of transport. Traffic (unfortunately) = only cars.

wuppidoc said...

Cambridge crossings: With this lay-out you can see the typical British engineering habitus. They want to get you safely over the crossing but do never consider to put cars second. It is always the cyclist and/or pedestrian that has to wait, cross, wait, cross etc. The idea of having one uninterrupted crossing for peds and cycs is never thought of. They think, this way they secure health and safety. But they would never consider any disadvantage for the motorised traffic. They fear congestion....

OldGreyBeard said...

Another annoying thing is that some of the pedestrian buttons in the UK are dummies.

Cyclo said...

Hi - can you give an explanation for the ticking in the video? Is it to help blind pedestrians?

David Hembrow said...

Cyclo: You guessed right. The ticking is to help blind people. The rate varies when the green light is lit for pedestrians.

WendyCarole said...

where I live in West Yorks the green man only seems to appear when the traffic has been stopped at the previous set of traffic lights. So quite often we are crossing on a crossing where there is no road traffic or just that caught between two sets of lights. This means a wait of quite a long time. One of the worse pedestrian crossings for this is outside a school. Then they wonder why the pupils get impatient and cross through the cars. Our cycle lanes are so sparse and pointless they aren't worth mentioning.
Most of the buttons on the crossings don't make the slightest bit of difference
I did get knocked down by a car on a belisha beacon crossing when I was nine (back in the 60s) because a car way back decided he was in too much of a hurry to wait in the queue.

Stefan Kaye said...

Another great post David - the worst set of pedestrian lights in Cambridge have to be the ones on Newmarket Road just outside the Cambridge United football ground, opposite Coldhams Common. When you press the button, even if no one has pushed it for ages, the lights will not turn green for pedestrians until either a significant gap appears in the road traffic in both directions or a considerable time, well in excess of a minute, has elapsed. Until recently, at the end of match, the police used to stop the traffic to let the crowds cross the road. Not any more, there is just a "safety notice" as you leave the ground instructing people to use the crossing. Now the crowds aren't what they used to be at United, but you're still talking a good couple of thousand people spilling on to the streets all at once. If even a quarter used the crossing we'd still be queued up an hour after the final whistle!

Gaz said...

I've written and made a video response. You have to love the UK!

David Hembrow said...

Gaz: Thanks. I'd already read it, but not quite got around to commenting ! If you look at the bottom of my post you'll see it's been updated with a link to yours.

vrataf said...

Nice post. I have done some calculation for Prague ( http://www.prahounakole.cz/2010/12/otravne-semafory/ , in Czech, unfortunately), comparing various kinds of light settings, from cycle lane (the same priority as cars), through old version of lights with fixed régime and without buttons, to "modern" version with button to push. The results were generally the same.

The most anxious was a comparison made for one 7 km long street, where I calculated delay for two variants of ride by bicycle: a) on bike lanes (with the same priority as cars - we may assume that this way cycle paths in Netherlands works) and b) on "czech version of cycle path" (assuming interruption on every from 50 corners and traffic lights on button on 16 main crosses).

The average speed would decrease from 20 to 12 km/h on the interrupted cycle path, whole journey would take 14 minutes longer and the extra energy necessary for repeated acceleration was equal to extra 80 meters high hill. One half of the time prolongation was caused by braking and acceleration on ~50 interruptions and one half by waiting for green signal on 16 traffic lights.

The result: While every interruption of cycle path is annoying (of course), traffic lights on button are annoying even three times more.

Mary said...

We were so excited to encounter sensors for cyclists in the Netherlands, and we were delighted to see a couple of them introduced in Minnesota recently.

Unfortunately, my commute to work is not one of the lucky routes. There is a traffic light with a button for pedestrians, and the light turns green very promptly -- if you arrive before 7 in the morning. During rush hour, the cars have priority. And why am I pushing the button? Well, my bike doesn't trigger the loop detector for car traffic, so if I don't ride up on the sidewalk and push the button, I can forget about ever seeing a green light.

Bryce P said...

David, the path in this video is obviously shared with pedestrians. How many similar paths are there? What criteria are there for determining whether a path be shared use and single use (cycle only)?

David Hembrow said...

Bryce,

If you look again at the video you'll notice that the crossings all separate pedestrians from cyclists. The first cycle-path also has clear separation between cyclists and pedestrians.

The cycle-path shown from 50 seconds in the video does not have a parallel pedestrian route. However, that is because there is little demand for use of this route by pedestrians. It is too long a stretch and almost all usage here is by cyclists.

This is the normal state of affairs. i.e. wherever there are likely to be significant numbers of pedestrians there is a separate pedestrian path. However out in the countryside, or in this case in the suburbs, where pedestrians are rare you will usually only find a cycle-path.

However, it is wrong to think that this is a shared-use path. It's not. It's a cycle-path on which pedestrians may walk. You won't find this arrangement anywhere that pedestrians are numerous.

In most countries in a similar situation you would likely find only a road. Pedestrians would be told to walk on the road facing traffic. The same happens here, but cycle-paths used in this way are considerably safer for pedestrians than is the road.

Paul Cooke said...

we have crossings at junctions in the UK where nothing actually happens to stop the traffic for pedestrians and cyclists, the buttons are just there to make you think something will happen. The green man & cycle symbols still appear at the same time it would have appeared during the cycle if you hadn't pressed the button...

David Hembrow said...

Paul, you're right. There were crossings like that near us in Cambridge. Truly awful. You know you're a second class citizen when even the pedestrian crossing is just a placebo.