Ask HN: What are you working on? (February 2025)

I live next to a school, so there's a low speed limit (30 km/h). Still, people drive like race drivers and the city hasn't ever responded to the residents' hopes of introducing a speed camera.

I wanted to have some data on how many people speed, the max speed recorded, that sort of thing. Things the city should be doing after many complaints of dangerous driving and people being almost killed on zebra crossings.

I have a doorbell camera, and by analysing the footage using OpenCV and some code, I can track how fast people drive if you see how fast they move between two known points.

Average speed: 46 km/h :(

The guy at Not Just Bikes will tell you that enforcement will never work nor happen and that the only way to get people to slow down is to design the road so it doesn't feel safe to drive fast.

The road next to my house has a speed limit of 20mph but most cars go 45mph because it's a straight road 4 lanes but space for 6. No bumps, no curves, wide. Effectively it feels like you should be driving fast. If I go the speed limit in the center lane because I'm going to turn left people will get angry and speed around at 60mph pissed off

Just out of curiousity, do you signal that you are going to turn left when you slow down compared to the average of the other drivers?

I don’t know about this person’s experience, but there are an overwhelming number of drivers here that don’t notice signals. I can be in the right lane (two lanes in both directions), signal a right turn, slow to turn and they’ll still ride right up on me and look pissed rather than go around.

It gets worse, some drivers seem to adopt an adversarial attitude towards the usage of turn signals and will deliberately accelerate or do something else to make things more difficult to you.

If they’re behind me, they’re risking their own liability.

Otherwise (changing lanes, left turn across traffic), I think it’s more “not ahead of ME!” than about the signal itself.

If two cars travelling the same direction contact each other such that the front axle of one car bumps the rear axle of the other (the car in front), it's usually the car in front that has the safety problem. This is the same principle behind the PIT maneuver.