200k Flemish drivers can turn traffic lights green • Hacker News Board

Re: 200k Flemish drivers can turn traffic lights green

#61

Post by de_huit » Mon, Jul 28, 2025, 1:41 PM UTC

PeterStuer wrote: post #42

Just in case you wonder, these are apps of commercial data-sharing/selling businesses, not some 'official' gov app for the benefit of the citizens. They are the products of https://ndrive.com/ , https://www.flitsmeister.nl and https://be-mobile.com/ . They also focus on toll collecting and parking fees, so "pay to play" is in a sense already in their DNA. Why do these commercial entities get to influence public traff…

Right. The government facilitates the commercial apps to communicate using the ETSI ITS standards with the traffic lights. For these protocols, lots of privacy discussions have taken place, like using different IDs at every intersection, and even hiding the line number of a bus. This make doing analyses like routing decisions pretty hard using only the public data. But the commercial apps have access to everything...

Re: 200k Flemish drivers can turn traffic lights green

#62

Post by camtarn » Mon, Jul 28, 2025, 1:44 PM UTC

jeroenhd wrote: post #25

OtherShrezzing wrote: post #13

I have no idea why the app is required here. Cars & bikes are massive, hot, & mobile objects. They're perfect for a modest-cost IR sensor atop the traffic light to detect them and adjust the lights accordingly. This type of system is commonplace in cities in the UK and works effectively. Having drivers reach for their phone when they're approaching traffic lights - common pedestrian crossing points - is categorically…

This isn't a system to detect if there are cars at an intersection. Wire loops and other systems already can and do measure cars like that. This is a system to detect "in 32 minutes, twenty-five cars will come from the south, crossing sixteen cars from the east. By pausing the western traffic lights for three seconds, both streams of cars can drive past each other without clogging up the main intersection". Users don…

Thank you, this is a much better explanation than in the article.

Re: 200k Flemish drivers can turn traffic lights green

#63

Post by sschueller » Mon, Jul 28, 2025, 1:50 PM UTC

kuon wrote: post #56

Here (switzerland) lights turn red on purpose to slow down traffic. The idea is that if you see a green light in the distance, you are motivated to speed up to catch it before it turns red. If it is red in the distance, you slow down because you eventually have to stop, and when you are like 20m from it, detectors will see you and turn it green.

Aka Grünewelle (Green-wave)[1] if you drive the speed limit every light you reach will turn green.

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

Re: 200k Flemish drivers can turn traffic lights green

#64

Post by ralferoo » Mon, Jul 28, 2025, 1:57 PM UTC

mosselman wrote: post #57

dalben wrote: post #49

Earlier quoted context omitted.

The concern was related to being able to know where emergency vehicles were. If you build a system that announces to traffic light “I’m police/fire/EMS, coming through”, you also build an early warning system for criminals and terrorists who either want to avoid or target you.

That doesn't make any sense. How would criminals know even if the traffic light receives a signal like that?

I think these systems used RF before, so anything in the vicinity could listen in. That said, if this new system is a phone app, it'll just be using phone data instead, so it'd be hard for that to be intercepted.

Re: 200k Flemish drivers can turn traffic lights green

#65

Post by 0_____0 » Mon, Jul 28, 2025, 1:59 PM UTC

cadamsdotcom wrote: post #51

Boltgolt wrote: post #48

Earlier quoted context omitted.

But highly susceptible to unauthorized use. The app version can also alert drivers directly with an audible alert that an emergency vehicle is close by

Fixable by taking a picture of every opticom user?

Or by doing even a slight amount of encoding of the IR signal. Transmitting a single byte as a key (set by region, same as fire dept. elevator keys) would be enough to prevent people from using their TV remote controls or whatever to trip the preempt sensors.

That being said, this is kind of a non-issue already, I have heard a story about someone abusing the preempt sensors like 10 years ago and never since then. Maybe there already exists an encoding scheme.

Re: 200k Flemish drivers can turn traffic lights green

#66

Post by rob74 » Mon, Jul 28, 2025, 2:09 PM UTC

kuon wrote: post #56

Here (switzerland) lights turn red on purpose to slow down traffic. The idea is that if you see a green light in the distance, you are motivated to speed up to catch it before it turns red. If it is red in the distance, you slow down because you eventually have to stop, and when you are like 20m from it, detectors will see you and turn it green.

My experience as a cyclist contradicts that: many motorists will still (riskily) overtake you just to reach the red light sooner. Some people apparently just can't stand to have anyone driving before them. See also: people passing by you on a multi-lane highway and then promptly slowing down once they have returned to your lane...

Re: 200k Flemish drivers can turn traffic lights green

#67

Post by potato3732842 » Mon, Jul 28, 2025, 2:13 PM UTC

kuon wrote: post #56

Here (switzerland) lights turn red on purpose to slow down traffic. The idea is that if you see a green light in the distance, you are motivated to speed up to catch it before it turns red. If it is red in the distance, you slow down because you eventually have to stop, and when you are like 20m from it, detectors will see you and turn it green.

Sounds like a great way to train people to run red lights. God only knows how many different industries best practices are being violated by that.

Re: 200k Flemish drivers can turn traffic lights green

#68

Post by arp242 » Mon, Jul 28, 2025, 2:17 PM UTC

dalben wrote: post #18

OtherShrezzing wrote: post #13

I have no idea why the app is required here. Cars & bikes are massive, hot, & mobile objects. They're perfect for a modest-cost IR sensor atop the traffic light to detect them and adjust the lights accordingly. This type of system is commonplace in cities in the UK and works effectively. Having drivers reach for their phone when they're approaching traffic lights - common pedestrian crossing points - is categorically…

That's not how it works - the idea is your navigation app signals the lights in advance. If you will reach red lights in 1km, the app signals this and the lights will be green before you're there, so you don't need to slow down.

Most people do not use a navigation app for most trips (i.e. commuting to work, grocery shopping, or whatnot).

Re: 200k Flemish drivers can turn traffic lights green

#69

Post by rob74 » Mon, Jul 28, 2025, 2:17 PM UTC

> A simple example: at night, a main road mainly displays green, the side streets only get green for a very short time. If you arrive with the app from a side street, you can get green immediately, provided there is no traffic on the main road.

In Germany, there's an established but much more low tech approach to this problem: simply turn off the traffic lights at night! All traffic lights already have yield/stop/priority signs as a fallback, so those take over. The yellow lights on the side street will usually flash as an additional warning so you don't overlook the yield/stop sign.

Re: 200k Flemish drivers can turn traffic lights green

#70

Post by potato3732842 » Mon, Jul 28, 2025, 2:21 PM UTC

gnfargbl wrote: post #50

jeroenhd wrote: post #25

Earlier quoted context omitted.

This isn't a system to detect if there are cars at an intersection. Wire loops and other systems already can and do measure cars like that. This is a system to detect "in 32 minutes, twenty-five cars will come from the south, crossing sixteen cars from the east. By pausing the western traffic lights for three seconds, both streams of cars can drive past each other without clogging up the main intersection". Users don…

Is that level of complexity actually necessary? The way that the UK system appears to work (as a user) is that the IR sensor detects a vehicle approaching the intersection from the minor road and, if there are no vehicles approaching on the major road, it gives you a green light by the time you actually reach the junction. I agree that the app-based system would theoretically be slightly better in that it has more in…

It's not strictly necessary but it takes giving a crap and effort and constant auditing and reassessing to do all that light timing well with the current state of technology. Outsourcing that responsibility to centralized computer that can do most of it automatically and on a schedule is likely a huge improvement for the quality of programming/timing for the average light if only a neutral for the best ones.