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Comment by chronofar | Hacker News Reader

I think that's an extremely suspect hypothesis. Most congestion is caused by:

- Construction

- Accidents

- Directly counter to your point: people driving like assholes and cutting others off or forcing others to take abrupt maneuvers that then cascade through the tightly packed traffic

Slow speeds and ample space do not cause congestion, changes in the flow of traffic do, and usually those are caused by people following too close and making sudden maneuvers. If enough space is given and the flow of traffic is not disrupted you could go as fast as you want with as many cars as you want and not experience congestion.

It's the mentality you're espousing here that I find so fascinating about road travel. There appears to be such dissonance that one will justify speeding or tailing or road rage in all kinds of ways.

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Too many cars on a certain section of the road at a certain point in time is congestion. This can be caused by many things, such as roadwork, collisions, but more often than not, it is simply a result of lots of people wanting to drive in the same direction on the same road at the same time. Aka rush hour.

I am not justifying road rage or tailgating. I am explaining that it is inevitable once the road gets close to carrying capacity, which can only be increased in the immediate term by driving faster and/or decreasing the distance of gaps between cars.

You say you're not justifying tailgating, but it sounds like your prescription for rush hour is exactly that.

I suppose there are different characteristics in different types of congestion. Stop and go congestion is usually caused by disruptions to the flow of traffic, while slower than usual congestion is indeed caused by over-capacity as you indicate. Just moving slower would be all such times would experience if not for people tailing and cutting others off, leading to the stopping part.

Even moving slower will not prevent stop and go traffic if the road has reached its capacity, due to the various different accelerations and decelerations of cars.

My overarching point is something like this video:

https://m.youtube.com/watch?v=Suugn-p5C1M

There simply is not a way to avoid the consequences of being near or above a road’s capacity. Of course, I recommend everyone to play it safe and stay far enough back to avoid any liability of being too close to the car in front. But the reality is we make lots of calculations and choices in driving and at various times, we choose farther distances and other times nearer distances (even though we know it is riskier) and these collective decisions will propagate down through the whole road.

> due to the various different accelerations and decelerations of cars.

Right, changes to the flow of traffic.

> There simply is not a way to avoid the consequences of being near or above a road’s capacity.

I agree, that is a valid bullet point. But that is certainly not the only cause of congestion, and driving aggressively in congestion and attempting to justify it by keeping the roads clearer doesn't hold a lot of water I don't think.

But I see you're saying you're not advocating unsafe driving so that's good, and I take your greater point, thanks for expounding on it.

You're doing static analysis on a dynamic situation. The biggest issue with overcapacity is the start of compression waves of traffic, which are generated much sooner by tailgaters slamming on their brakes in a panic with each following vehicle having to brake harder than the one in front, eventually coming to a complete stop (or just causing an accident).

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