Shining a light on the traffic signals of Sydney | Hacker News Reader

Shining a light on the traffic signals of Sydney

jakecoppinger.com

50 pointsjakecopp42 comments

Why do pedestrians in Sydney wait so long at traffic lights? I tried to find out the answer to this simple question and wrote a blog post of my findings - keen to hear your thoughts!

I cover and share previously unpublished maps of signal timings, ODbL crowdsourced data from a open source website I built, how it costs $200 to buy data on a single intersection from the state government, details on signal programming in a proprietary plain text format, comparisons with best practice in Copenhagen and elsewhere, and what's in store for the future of traffic signals in Australia.

Sydney is an important study location as it is the birthplace and development location of the Sydney Coordinated Adaptive Traffic System (abbreviated SCATS).

Our government sells the system commercially to 30 countries and 200 cities around the world. We are quite literally exporting our biases. Countries that use Australia's traffic light system include New Zealand, Hong Kong, Shanghai, Guangzhou, Amman, Tehran, Dublin, Rzeszów, Gdynia, Central New Jersey, and in part of Metro Atlanta. [1]

[1]: https://en.wikipedia.org/wiki/Sydney_Coordinated_Adaptive_Tr...

> Why do pedestrians in Sydney wait so long at traffic lights?

They don't immediately cross when they get a walk signal?

They do - however it may be multiple minutes before they get a green walk signal unfortunately.

The city of Bellevue WA adopted SCATS a few years ago and driving there seems much more pleasant now. I can drive from downtown Bellevue to the Microsoft campus and often face only two red lights (if you know the area: crossing 20th St/Northrop Way and then turning left onto 156th Ave). Before you would be stuck at a bunch of red lights after the cross traffic was long gone. And almost every intersection now has permissive left turns where before you’d have to wait on an unnecessarily long red arrow. Don’t know how “dumb” their system was before but it’s been a big improvement.

What's the pedestrian experience like now compared to before?

No idea. Bellevue is pretty suburban. Most people drive, it’s too spread out to walk many places.

"As a result of these decisions, this results in the Sydney CBD effectively operating as a fixed time system during peak – that is, the phase lengths are very similar to the expected, pre-programmed length."

Does this mean that for pedestrian walk times to be increased, there must necessarily be a reduction of cars within Sydney city?

It is funny that the 'adaptive' system is flooded so it becomes a fixed system. The City of Sydney is going to have to recognise that to increase economic activity in the city there will have to be a reduction of cars to allow more persons access to this important economic space.

Another big point I think is the idea of a wave of green lights so cyclists do not have to stop every block. Could a 'wave' idea also be used for cars to progress quicker - or will it just slow down other cars further?

This is a really great analysis and wonderful blog post - keep up the great work.

FWIW City of Sydney has ample space for pedestrians and along with state governments has done a lot to reduce car traffic, including largely repurposing the central road running down it (George St) for light rail and pedestrians. There are also many large pedestrian only “malls”.

I've seen waves implemented on some streets in Canada (for cars). I don't know how you make it work in both directions though. Maybe you just do it in the direction with more traffic.

In my (US) city, they do this timing only on one-way streets.

In case you're not aware, and im not sure about the "economic outcome", but The City of Sydney pedestrianised the main street through the city about 6 years ago when they also installed light rail, and it looks like they're extending it even further. https://community.sydneycivil.com/george-street-south-pedest...

I’ve seen the wave idea implemented, and if you can actually drive the speed limit they are quite nice. However with the inconsiderate types out there blocking lanes and other examples, it’s not always easy to catch. Also, the speed limits tend to be a bit faster than a bike will be going.

> I’ve seen the wave idea implemented, and if you can actually drive the speed limit they are quite nice.

A bunch of the streets in my city do this, and it's awesome. Particularly when there's another car that doesn't know about it, so they're constantly speeding to next red light, where my relatively sedate pace gets me constant green lights, and I smile as I repeatedly pass the speeder that is trying to accelerate from a complete stop.

There's only 2 streets that i know of that were designed this way, but like i mentioned, the streets are usually too encumbered to actually get it to work. I haven't been downtown since pre-covid to know if they are even attempting to still do it.

Quite a few streets in my city do this, but only if you drive 10mph over the speed limit.

Yeah chicago works like this if you go 10 over and blast every yellow. Not sure if that's just civil engineering realism or what.

I thought the whole point was to reward/encourage drivers for driving the limit, not speeding. This seems very odd

Yes. It directly conflicts with the large signs they have posted, touting the benefits of going the speed limit.

I've seen this a number of times. One time, I got a clue as to how it comes about -- I travelled a 35MPH road with synchronized signals, and the city reduced the speed limit to 30, but didn't go to the trouble to adjust the light timing to match.

It works incredible well for bicycles though, as is stated in the article 17% decrease of travel time has been shown. This mirrors my experience, though it suffers alot if there is one or two non synchronized lights at the edges of a wave.

> The City of Sydney is going to have to recognise that to increase economic activity in the city there will have to be a reduction of cars to allow more persons access to this important economic space.

The City of Sydney _council_ definitely realises this - however the state transport agency (TfNSW) has historically prioritised vehicle throughput over placemaking, though the Movement and Place Framework is starting to change this (this framework takes a lot of inspiration from Gehl's work).

I had never heard the term "scramble crossing" so I looked it up, and found this gem, from the former traffic commissioner of NYC:

"As things stood now, a downtown shopper needed a four-leaf clover, a voodoo charm, and a St. Christopher's medal to make it in one piece from one curbstone to the other. As far as I was concerned — a traffic engineer with Methodist leanings — I didn't think that the Almighty should be bothered with problems which we, ourselves, were capable of solving."

Also known as a "Barnes dance" crossing (in NZ at least)

Excessive wait times with no danger is exactly why many of us on foot or bike will cross on a red light.

Figures this out pretty quick in Europe too. The locals don't wait. There's lots of times when there's clearly no cars coming.

California also doesn't have jaywalking fines anymore I think, so... Yeah I'm just going to cross where/when I think it's safe. Which is also often NOT when it's green because cars be crazy.

You usually don't get jay walking tickets in Australia. So most people just make adult decisions about their safety and manage for themselves.

Interesting. I was reading a HN comment last month about how Australians are 'disgustingly... devoted to following tiny guidelines' [1], so it's interesting to hear this aspect of freedom. I'm generally not inclined to believe that Australians manage for themselves, given the previous comment was first and takes precedence.

1: https://news.ycombinator.com/item?id=36457222

My Australian kids and 9 and 11 and we are very strict about waiting for the walk signal. Kids that age tend to walk around daydreaming, and just not great at working out how fast cars are moving. Crossing a busy road is literally the most dangerous thing they do.

Another cultural observation, when living in Boston, my partner and I both found it strange that if you were standing on the side of the road, cars will stop and wait for you to cross, even if you were nowhere near a crossing or intersection. Cars seems to give way to pedestrians anywhere an everywhere.

In Australia, cars wont stop for you unless you are at a crossing, and even then you need to make sure they have seen you. Cars zooming through a green light are not going to be looking for pedestrians walking against a red walk signal. The onus is on the pedestrian to not be hit, not the car to avoid the pedestrian.

Update: Also.. its hard not to take this persons criticism personally, so when they say "the UK / Australia model where everyone obeys some stupid rule written on the wall over their own intelligence" I would just like to respond that is a combination of wanting to be polite and courteous to the sign poster, and intelligent enough to know we don't know everything, that the sign might be for our own safety. :)

Massachusetts in general has that cultural quirk and raising children there it actually concerned me. If they were trained to think that cars would stop for them and went to pretty much anywhere else, they'd be flattened. I remember just standing on the sidewalk one time, probably close to the curb, and a car came to a stop behind me to patiently wait. It seemed odd, and socially the fact that I wasn't interested in crossing seemed like they might take disrespect from it. But it was their assumption about me.

You can always have cautious children become more adventurous later, but it's unlikely to ever go the reverse direction.

This is how traffic should be, everyone should communicate clearly and give way to pedestrians, including bicycles, Amsterdam cyclists are horrible at this. About your fear the fix is to tell your kids to look for that communication as well.

My breakfast view is a school crosswalk and all children wait for cars and cyclists, most even wait for a complete stop before crossing (N=100).

Crossing roads is a fairly common counterexample of the overall trend.

Australians for the most part are absolutely "disgustingly devoted to following tiny guidelines", but jaywalking is also extremely common.

Having many tiny inconsequential rules allows you many daily transgressions. It helps you to keep the self delusion that you too are just a little Aussie larikin, and assuage your guilt when you call the cops on that neighbour stealing from your hard rubbish collection.. cos that cunt just took it too far.

Ironic statement, considering Australia has a reputation of being considered a 'nanny state'.

I find the branding of 'nanny state' really odd. And I can't really think of much you can't do here outside of fireworks and guns, and even then just go to a rural area. Maybe it's just me, I guess there's a lot of laws, but we also have a lot of government services and a stable functioning democracy as a consequence of following those laws.

Like it's rare for kids to die at school here. They don't get shot. So that's something.

If you "jaywalk" within 20 metres of an intersection you can be fined. This is fairly common if police are doing a blitz - I've seen it happen near universities and high schools.

If you don't already know, you should read about the historical origin of the term: https://en.wikipedia.org/wiki/Jaywalking#Origin_of_the_term

I've done low-level work in C++ with SCATS, about a decade ago. It was a challenging API to work with, not fully documented and a lot of strange timing "phenomena".

Interesting - could you explain more about the strange phenomena and lack of documentation?

I've heard there is still present issues with lack of documentation, and more experienced folk having left the development team.

SCATS was originally based on LSI-11 (pizza-box sized PDP-11) hardware. I wouldn't be surprised if considerable legacy code still lurks in there. Don't know what the current hardware is - hope it's not Windows 3.11 PCs. (Don't laugh, a few years ago I was working with ATMs for a large bank, inside the ATMs were beige PCs running Windows 3.11).

Lots of the screenshots in the article show the software running on XP.

Don't forget the most familiar sound of the PB/5 pedestrian button, which every emo kid in the world has known and loved since 29 March 2019. Groovy stuff, Australia!

I love Sydney's pedestrian crossing call buttons. They make this 80s videogame sound when it's time to cross :) Well they did when I was there in the early 2000s.

Sydney's streets were laid out over a century ago. They barely coped with horse and carriage traffic. Now we have Pitt St Mall and George St is mostly closed for the trams. Many streets have been narrowed to allow for bicycle paths.

So car, truck, taxi, ride-share, delivery van traffic has been funneled onto ever dwindling number of roads and parking has become extremely scarce. As a result congestion has gotten worse.

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