Hacker News Reader

Comment by JakeTheAndroid | Hacker News Reader

To be honest, I'd happily let my car mess up the flow of traffic trying to block the box. The only reason this exists is because everyone decides to enter the box to make the light.

When working in SF without self driving I would regularly not let myself block the box and I'd miss multiple lights. Police need to actually ticket people that do this. I've seen cops sitting at the intersection waiting to ticket people for bypassing traffic by using the carpool freeway entrance while doing fuckall about the blocked intersection causing people to want to choose the HOV option.

I understand that it's a part of driving that a self driving car would need to know how to navigate. But we really should just fix this problem through proper traffic enforcement instead of trying to make self driving cars participate in this completely shitty and unnecessary practice.

View on HN

I agree with you in principle about not blocking the box. But in practice it's not always like that. Sometimes the actual light timing needs to change. Sometimes the roads need to just be different than they are to prevent bottlenecks, which is a pretty expensive fix

Sometimes you roll up to an intersection, and every time the light turns green, the direction you're trying to go already has all lanes filled by another approaching direction. Every time.

Classic prisoners dilemma. The lanes are blocked because the people up ahead are thinking the same thing.

My experience... the lanes are usually blocked because some other lane, coming some other direction, has much better access to those lanes because of how the signal timing works at the intersection.

A common scenario is: you're heading east, want to head north. When space opens up heading north, northbound traffic has a green light and fills it up. When you have a green light, there is no space.

I could imagine that left turns like you mentioned would be systematically disadvantaged, but doesn't that just mean you should circle around so that you are going north? If instead you were going west and competing against northbound traffic I find it hard to believe you would be systematically disadvantaged; a space is equally likely a priori to clear out when you have a green as when they have a green, no?

Space clears out when traffic upstream starts to move. If the next traffic light upstream is synced to the current one, then space will consistently open up at the same point in the cycle, favoring whichever direction has the green at that point. If the lights are almost but not quite synced, then the "favored direction" will gradually cycle around the intersection over time.

> circle around

This is generally not possible, especially for the kind of intersections that have this problem. There generally is not a short path that would allow you to circle around, and even if there is, it's guaranteed to be completely congested by everyone else trying the same trick.

This is - imo - the biggest issue with traffic everywhere. It's a game theory problem, where being greedy is often the best move.

The spring paradox is a neat example of this: https://youtu.be/Cg73j3QYRJc

The shortest route only remains the shortest if a minority take it.

>Sometimes you roll up to an intersection, and every time the light turns green, the direction you're trying to go already has all lanes filled by another approaching direction. Every time.

The only time I can imagine this happening is when trying to turn left, at which point the solution is to go past the turn, double back, and approach the intersection so you can make the turn from the right.

Imagine you want to go straight, but there is an overwhelming quantity of traffic that is turning right. And the lights are badly timed, so the traffic on the other side of the intersection does not make any progress during your green light.

Really, Manhattan is just a terrible place to drive. A horribly congested island with limited ways in and out, that is also sometimes the lowest-cost way to get between the mainland and geographic Long Island. The same goes for the rest of NYC to a lesser extent; shoutouts to Elmhurst and Flushing for being particularly terrible places to drive.

Not a morning goes by without a report of "45 minutes/1 hour to the Holland Tunnel." There isn't really a scalable fix for the solution that involves road capacity.

> Really, Manhattan is just a terrible place to drive. A horribly congested island with limited ways in and out ...

Manhattan is a wonderful place to drive, my favorite place to drive by far; it's how I instinctively drive but can't everywhere else. It's the most sophisticated driving, not the lowest common denominator; people have to focus on what they are doing - don't start texting. Like the rest of the island - more people is more life, more energy. That's why people have loved NYC for centuries. (Sorry to get corny, but there are plenty of songs about it.)

> Not a morning goes by without a report of "45 minutes/1 hour to the Holland Tunnel."

If you stop thinking about NYC driving distances as physical, but in terms of time, that's just how 'long' the Holland Tunnel is.

How expensive can it really be to put up a "NO TURN ON RED" sign?

Reply on news.ycombinator.com