from Hacker News

Shining a light on the traffic signals of Sydney

by jakecopp on 7/10/23, 10:07 PM with 42 comments

• by jakecopp on 7/10/23, 10:11 PM

  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  I cover and share previously unpublished maps of signal timings, ODbL crowdsourced data from a open source website I built, how it costs $200 to buy data on a single intersection from the state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...

• by getwiththeprog on 7/11/23, 7:01 AM

  "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.

• by myself248 on 7/11/23, 8:53 PM

  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."

• by quantified on 7/11/23, 12:36 AM

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

• by eisvogel on 7/11/23, 11:50 PM

  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".

• by NoZebra120vClip on 7/12/23, 8:25 AM

  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!

• by wkat4242 on 7/12/23, 9:40 AM

  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.

• by GianFabien on 7/12/23, 6:46 AM

  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.