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Comment by ora600 | Hacker News Reader

Years ago I've read an article that recommended doing this manually as a way to assist the flow of traffic.

I thought its a nice idea and tried it. Unfortunately, I tried this in Tel-Aviv, where drivers from other lanes immediately moved their cars into the space that opened between my car and the one ahead of me. It didn't take me long to figure out that I'm getting nowhere.

Two years later, when I moved to the bay area, I tried it on the 101 during rush hour traffic. To my shock, it worked. It was exceedingly rare to have any car move into that space. Or move lanes in general. For some reason (laziness? safety?), California drivers don't switch lanes as much as Israeli drivers do.

Moral: There's time and place for every algorithm.

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Bay area and LA drivers are very different. LA driving is more similar to Tel Aviv driving, if you want a taste of home :)

Bay area drivers have this weird sense of "lane ownership". They don't change lanes... and they don't let anyone come in! It's not the sort of "Won't let you cut in front of me!" that you sometimes see in Israel, but a general thing. Even if you need to change lanes to exit and it's clear you're going to exit right away, I've had countless drivers speed up and block me from merging to the right.

This weird quirk does make it useful for applying traffic wave theory, so at least there's one good outcome.

I've used a variant of this successfully when there's a merge coming up. Basically, if I'm in the lane that's disappearing, I slow down as if to merge, matching speed with the car next to me, but then don't merge until the last moment. When I do this I invariably get some hotshot honking behind me who wants to zip up to the merge point and slow down traffic there, but such people are essentially the cause of the problem, so I don't worry too much.

What generally happens is that from the moment I start doing this, overall traffic speeds up just a bit and the lane ahead of me clears fairly quickly. It's win-win for everyone but the hotshot behind me.

Actually, this is suboptimal.

The optimal flow is for everyone to use both lanes up until the last moment, and then to merge by alternation (one car from one lane goes, then one car from the other lane goes).

Unfortunately, this only works when a substantial majority of the drivers understand that this is how it should work. If you don't hit that threshold, then the people who use the disappearing lane are going to get glares.

Here's a link that describes the theory behind optimal merge patterns:

http://jksqr.blogspot.com/2008/09/optimal-lane-merging-part-...

Actually he may be forcing the lanes-full optimal mode to arise.

If one or a few drivers in the empty lane start pacing the cars in the full lane, cars will build up behind them. When they arrive at the end of their lane, the drivers in the full lane won't be so ready to block merges (since nobody was cheating by racing down to the end.) Perhaps this could trigger an outbreak of zipper-merging.

So, what you're saying is: your solution is optimal in theory but suboptimal in practice, and the grandparent's theory is suboptimal in theory but optimal in practice. Right?

http://trafficwaves.org/

He has updated it since '98, and even bought a domain! But yeah, it does work.

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