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When I moved from Europe to Sydney, it was striking how much traffic lights deprioritised walking. Visitors have independently commented on similar things. Its

When I moved from Europe to Sydney, it was striking how much traffic lights deprioritised walking. Visitors have independently commented on similar things. Its not just timing, but also inefficient phases. I requested the dataset for phases, but after months was given a totally different dataset. I gave up.

shortcake27 3y ago
Melbourne is the same. Buttons that change the timing are rare or maybe even non-existent. I can’t think of any intersections where pressing the button does anything other than activate the pedestrian lights.
- bobthepanda 3y ago
  I have never seen an intersection where beg buttons favor pedestrians and not drivers, because beg buttons give engineers the latitude to establish red crosswalks unless requested. So help you if you arrive just in time to miss your activation cycle and have to wait a full light cycle for the crosswalk.
  - danhor 3y ago
    I've seen quite a few intersections (Germany) that only feature one car road, but a crossing pedestrian/bike street that after pressing the beg button immediately begin to switch the light, resulting in a consistent, short wait (apart from signal priority stuff for busses). But anything more complicated, nothing comes to mind.
    - Someone 3y ago
      https://bicycledutch.wordpress.com/2016/06/21/traffic-lights-in-s-hertogenbosch-an-interview/ https://bicycledutch.wordpress.com/2016/06/21/traffic-lights... has plenty examples of things more complicated, for example: “In the past, buses always got priority. Now every bus is tagged and the computer knows all the time-tables of every line. The system knows exactly when which bus needs to arrive at a certain intersection. The installation checks whether a bus is too early, on time, or running late and sets the lights accordingly.” “On the cycleways we always have double loops, separated by 75 centimetres. That way we can measure speed and direction by combining the data the computer receives from the two loops. It also means we don’t need to reserve green time for a cyclist riding against traffic, away from the intersection.” And the pushbutton? “For cyclists that’s not really necessary. They’re only there for reassurance. You often see in the reports that people don’t even bother to push the button.”
      - bobthepanda 3y ago
        But there the priority is pretty much everything else other than the beg button. I can't help but wonder if such aggressive timings discussed in the article are good for people with disabilities. People often panic when rushed by a change to red.
  - toast0 3y ago
    I've experienced plenty of beg buttons that don't do anything other than activate the crossing light when that direction next goes green for cars. But also plenty where pressing the button takes immediate steps for the pedestrian: if the direction is already green for cars, the walk sign is turned on; otherwise, the current cycle ends and any intermediate cycles proceed with minimum duration; non-dominant directions will have longer minimum cycle time if the pedestrian button has been pressed. In my experience, if the intersection processes car traffic dynamically, it will also process pedestrian traffic dynamically, and generally favor pedestrians. If the intersection has static timing, it's not going to do anything different for pedestrians. I recall driving in Milwaukee near UWM two decades ago, every morning I could count on the lights showing exactly the same thing at the same time. If I left my apartment at the same time, I'd get the same sequence of missed or made lights. Most other places I've driven had car sensors (usually loops in the pavement, but cameras are cheaper and less maintenance now), so there's no schedule to be learned, although the behavior is predictable if you learn the cycles and observe the stimuli. (Although, sometimes sensors are broken or miswired; there was an intersection near one of my employers where the cyclist button was connected as an left turn lane occupancy sensor; resulting in consistently wrong behavior. it's also not uncommon for a disabled vehicle to be located above a loop, or sometimes a construction / utility vehicle to be parked above a loop; some control systems can adapt and filter that out, but many don't.)
    - whophd 3y ago
      I don’t see beg buttons in Sydney that turn green mid-phase — where are these? You always have to wait for a complete phase (which can be shortened, with no traffic and no area phasing) before the pedestrian signal is allowed to turn green again. The only partial exception is pedestrian-only crossings and then only if you are in the part of the phase where enough time still is available to return cars to green.
  - jakecopp 3y ago
    I also wrote a blog post on beg buttons in the Sydney CBD: https://jakecoppinger.com/2022/12/sydney-cbd-is-bringing-back-pedestrian-beg-buttons/ https://jakecoppinger.com/2022/12/sydney-cbd-is-bringing-bac... (194 comments on HN: https://news.ycombinator.com/item?id=34058004 https://news.ycombinator.com/item?id=34058004)
- Someone 3y ago
  > Buttons that change the timing are rare or maybe even non-existent Buttons are old tech. https://www.flir.com/products/trafione/ https://www.flir.com/products/trafione/: “The FLIR TrafiOne uses thermal imaging and Wi-Fi technology to adapt traffic signals based on the presence detection of vehicles, bicycles and pedestrians, even in total darkness or adverse weather.” I don’t know how smart that version is, but there are versions that predict whether pedestrians have the intention to cross the street. https://www.tugraz.at/en/tu-graz/services/news-stories/tu-graz-news/singleview/article/denkende-fussgaengerampeln-neues-system-der-tu-graz-erkennt-kreuzungswunsch-automatisch0/ https://www.tugraz.at/en/tu-graz/services/news-stories/tu-gr...: “The innovative camera-based system recognises the intention of pedestrians to cross the road and switches to green automatically. What’s more, it optimises the traffic flow further, as Horst Possegger from the Institute of Computer Graphics and Vision explains by way of two examples: “The green phase can be extended in the case of large groups of persons, who require more time to cross the road. And if persons leave the waiting area before the lights have turned to green, this is also passed on to the lights. The traffic lights subsequently don’t switch to green and there are no unnecessary waiting times for motorised traffic.” […] “Using the current configurations, our system signals that wish to cross three to four seconds before the button is pushed,” says Possegger.”
  - reaperman 3y ago
    Feels like you could do that somewhat cheaper with just visual cameras and any off-the-shelf YOLOv# detection model.
    - kimixa 3y ago
      For the pedestrian problem at least, it seems even cheaper to just use a button. That also completely bypasses the problem of trying to detect if they intend to cross. Is there really much of a disadvantage? The pedestrian has to be in a specified area beside the crossing already to use it, so likely within arms reach of a pole already. But I can see it being useful for cars and bikes - as a cyclist I've hit a good number of times the magnetic sensors clearly just don't work for a bike, and had to wheel over to the pedestrian crossing to press the button to get the lights to change. And I expect "person detection" to be much easier with an IR image, there's probably not many places where human body temperature isn't noticeably higher than the background should make it more accurate to pick out. And if you don't need accuracy of temperature reading, an IR camera isn't really any more expensive than a visual camera - it's the same CCD just with a different filter on top. And it completely bypasses any problems of darkness. I also wouldn't be surprised if the actual camera unit was a near negligible cost of installing something like this, so even if it was multiples of the price, optimizing for that may be the wrong target if it affects accuracy at all.
gtmb 3y ago
Australia is at least 40 years behind in traffic management. There is no traffic lights priority for public transport. Melbourne's tram avg speed is 10-15 kph. If you power walk you can go faster than the tram. It just sits there waiting on traffic lights more than moving. There is no synced traffic lights. On long avenues you just stop every 200m because once the light goes green when you arrive at the next intersection the light there goes red. It seems it is synced, but to the opposite it should be doing.
- madeofpalk 3y ago
  Sydney's traffic light system (Sydney Coordinated Adaptive Traffic System, or SCATS) is supposedly "a recognised worldwide market leader in intelligent transport systems" and has been exported to a bunch of cities around the world. It does (supposedly) prioritise public transport in phase timings. https://en.wikipedia.org/wiki/Sydney_Coordinated_Adaptive_Traffic_System https://en.wikipedia.org/wiki/Sydney_Coordinated_Adaptive_Tr... > On long avenues you just stop every 200m because once the light goes green when you arrive at the next intersection the light there goes red. It seems it is synced, but to the opposite it should be doing. I recall a link a while back (from HN?) that demonstrated that it's basically impossible to sync green traffic lights in both directions. Any attempt at syncing will priotitise one direction over the other. I can't find the source, and it was so long ago that it's very likely that I'm misremembering.
  - csunbird 3y ago
    Germany does it very well. Until I make a turn, I do not wait at red lights more than once or twice.
  - iggldiggl 3y ago
    > it's basically impossible to sync green traffic lights in both directions. For a bi-directional green wave, intersections have to be spaced at intervals consistent half the cycle time (times the intended travel speed) of the traffic lights. In that case opposing vehicle streams will always meet each other at an intersection, thereby minimising the green time required along the green wave and maximising the green time available for handling crossing and turning traffic. If an intersection deviates from that mathematically optimal location, it means that there'll be less of an overlap between the green times for the two opposing direction, meaning that there's less green time left over for cross traffic. And since in real life, intersections are rarely spaced at the mathematically optimal interval, in practice this means that eventually you have to give up and just favour one direction depending on the time of the day. (To some extent you can try to salvage things by varying the assumed speed between intersections in order to keep the travel time from intersection to intersection constant, but there's only a limited usable speed range between too slow and the legal speed limit.) And if you attempt to have multiple green waves crossing each other, you introduce even more scheduling constraints which might leave no room for a perfect solution.

shortcake27 3y ago

Melbourne is the same. Buttons that change the timing are rare or maybe even non-existent. I can’t think of any intersections where pressing the button does anything other than activate the pedestrian lights.

bobthepanda 3y ago
I have never seen an intersection where beg buttons favor pedestrians and not drivers, because beg buttons give engineers the latitude to establish red crosswalks unless requested. So help you if you arrive just in time to miss your activation cycle and have to wait a full light cycle for the crosswalk.
- danhor 3y ago
  I've seen quite a few intersections (Germany) that only feature one car road, but a crossing pedestrian/bike street that after pressing the beg button immediately begin to switch the light, resulting in a consistent, short wait (apart from signal priority stuff for busses). But anything more complicated, nothing comes to mind.
  - Someone 3y ago
    https://bicycledutch.wordpress.com/2016/06/21/traffic-lights-in-s-hertogenbosch-an-interview/ https://bicycledutch.wordpress.com/2016/06/21/traffic-lights... has plenty examples of things more complicated, for example: “In the past, buses always got priority. Now every bus is tagged and the computer knows all the time-tables of every line. The system knows exactly when which bus needs to arrive at a certain intersection. The installation checks whether a bus is too early, on time, or running late and sets the lights accordingly.” “On the cycleways we always have double loops, separated by 75 centimetres. That way we can measure speed and direction by combining the data the computer receives from the two loops. It also means we don’t need to reserve green time for a cyclist riding against traffic, away from the intersection.” And the pushbutton? “For cyclists that’s not really necessary. They’re only there for reassurance. You often see in the reports that people don’t even bother to push the button.”
    - bobthepanda 3y ago
      But there the priority is pretty much everything else other than the beg button. I can't help but wonder if such aggressive timings discussed in the article are good for people with disabilities. People often panic when rushed by a change to red.
- toast0 3y ago
  I've experienced plenty of beg buttons that don't do anything other than activate the crossing light when that direction next goes green for cars. But also plenty where pressing the button takes immediate steps for the pedestrian: if the direction is already green for cars, the walk sign is turned on; otherwise, the current cycle ends and any intermediate cycles proceed with minimum duration; non-dominant directions will have longer minimum cycle time if the pedestrian button has been pressed. In my experience, if the intersection processes car traffic dynamically, it will also process pedestrian traffic dynamically, and generally favor pedestrians. If the intersection has static timing, it's not going to do anything different for pedestrians. I recall driving in Milwaukee near UWM two decades ago, every morning I could count on the lights showing exactly the same thing at the same time. If I left my apartment at the same time, I'd get the same sequence of missed or made lights. Most other places I've driven had car sensors (usually loops in the pavement, but cameras are cheaper and less maintenance now), so there's no schedule to be learned, although the behavior is predictable if you learn the cycles and observe the stimuli. (Although, sometimes sensors are broken or miswired; there was an intersection near one of my employers where the cyclist button was connected as an left turn lane occupancy sensor; resulting in consistently wrong behavior. it's also not uncommon for a disabled vehicle to be located above a loop, or sometimes a construction / utility vehicle to be parked above a loop; some control systems can adapt and filter that out, but many don't.)
  - whophd 3y ago
    I don’t see beg buttons in Sydney that turn green mid-phase — where are these? You always have to wait for a complete phase (which can be shortened, with no traffic and no area phasing) before the pedestrian signal is allowed to turn green again. The only partial exception is pedestrian-only crossings and then only if you are in the part of the phase where enough time still is available to return cars to green.
- jakecopp 3y ago
  I also wrote a blog post on beg buttons in the Sydney CBD: https://jakecoppinger.com/2022/12/sydney-cbd-is-bringing-back-pedestrian-beg-buttons/ https://jakecoppinger.com/2022/12/sydney-cbd-is-bringing-bac... (194 comments on HN: https://news.ycombinator.com/item?id=34058004 https://news.ycombinator.com/item?id=34058004)
Someone 3y ago
> Buttons that change the timing are rare or maybe even non-existent Buttons are old tech. https://www.flir.com/products/trafione/ https://www.flir.com/products/trafione/: “The FLIR TrafiOne uses thermal imaging and Wi-Fi technology to adapt traffic signals based on the presence detection of vehicles, bicycles and pedestrians, even in total darkness or adverse weather.” I don’t know how smart that version is, but there are versions that predict whether pedestrians have the intention to cross the street. https://www.tugraz.at/en/tu-graz/services/news-stories/tu-graz-news/singleview/article/denkende-fussgaengerampeln-neues-system-der-tu-graz-erkennt-kreuzungswunsch-automatisch0/ https://www.tugraz.at/en/tu-graz/services/news-stories/tu-gr...: “The innovative camera-based system recognises the intention of pedestrians to cross the road and switches to green automatically. What’s more, it optimises the traffic flow further, as Horst Possegger from the Institute of Computer Graphics and Vision explains by way of two examples: “The green phase can be extended in the case of large groups of persons, who require more time to cross the road. And if persons leave the waiting area before the lights have turned to green, this is also passed on to the lights. The traffic lights subsequently don’t switch to green and there are no unnecessary waiting times for motorised traffic.” […] “Using the current configurations, our system signals that wish to cross three to four seconds before the button is pushed,” says Possegger.”
- reaperman 3y ago
  Feels like you could do that somewhat cheaper with just visual cameras and any off-the-shelf YOLOv# detection model.
  - kimixa 3y ago
    For the pedestrian problem at least, it seems even cheaper to just use a button. That also completely bypasses the problem of trying to detect if they intend to cross. Is there really much of a disadvantage? The pedestrian has to be in a specified area beside the crossing already to use it, so likely within arms reach of a pole already. But I can see it being useful for cars and bikes - as a cyclist I've hit a good number of times the magnetic sensors clearly just don't work for a bike, and had to wheel over to the pedestrian crossing to press the button to get the lights to change. And I expect "person detection" to be much easier with an IR image, there's probably not many places where human body temperature isn't noticeably higher than the background should make it more accurate to pick out. And if you don't need accuracy of temperature reading, an IR camera isn't really any more expensive than a visual camera - it's the same CCD just with a different filter on top. And it completely bypasses any problems of darkness. I also wouldn't be surprised if the actual camera unit was a near negligible cost of installing something like this, so even if it was multiples of the price, optimizing for that may be the wrong target if it affects accuracy at all.

gtmb 3y ago

Australia is at least 40 years behind in traffic management. There is no traffic lights priority for public transport. Melbourne's tram avg speed is 10-15 kph. If you power walk you can go faster than the tram. It just sits there waiting on traffic lights more than moving. There is no synced traffic lights. On long avenues you just stop every 200m because once the light goes green when you arrive at the next intersection the light there goes red. It seems it is synced, but to the opposite it should be doing.

madeofpalk 3y ago
Sydney's traffic light system (Sydney Coordinated Adaptive Traffic System, or SCATS) is supposedly "a recognised worldwide market leader in intelligent transport systems" and has been exported to a bunch of cities around the world. It does (supposedly) prioritise public transport in phase timings. https://en.wikipedia.org/wiki/Sydney_Coordinated_Adaptive_Traffic_System https://en.wikipedia.org/wiki/Sydney_Coordinated_Adaptive_Tr... > On long avenues you just stop every 200m because once the light goes green when you arrive at the next intersection the light there goes red. It seems it is synced, but to the opposite it should be doing. I recall a link a while back (from HN?) that demonstrated that it's basically impossible to sync green traffic lights in both directions. Any attempt at syncing will priotitise one direction over the other. I can't find the source, and it was so long ago that it's very likely that I'm misremembering.
- csunbird 3y ago
  Germany does it very well. Until I make a turn, I do not wait at red lights more than once or twice.
- iggldiggl 3y ago
  > it's basically impossible to sync green traffic lights in both directions. For a bi-directional green wave, intersections have to be spaced at intervals consistent half the cycle time (times the intended travel speed) of the traffic lights. In that case opposing vehicle streams will always meet each other at an intersection, thereby minimising the green time required along the green wave and maximising the green time available for handling crossing and turning traffic. If an intersection deviates from that mathematically optimal location, it means that there'll be less of an overlap between the green times for the two opposing direction, meaning that there's less green time left over for cross traffic. And since in real life, intersections are rarely spaced at the mathematically optimal interval, in practice this means that eventually you have to give up and just favour one direction depending on the time of the day. (To some extent you can try to salvage things by varying the assumed speed between intersections in order to keep the travel time from intersection to intersection constant, but there's only a limited usable speed range between too slow and the legal speed limit.) And if you attempt to have multiple green waves crossing each other, you introduce even more scheduling constraints which might leave no room for a perfect solution.