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Comment by efsavage | Hacker News Reader

Sorry I can't resist the pedantry but a traffic engineer knows better than anyone that adding a 5th lane (often even a 4th) won't improve traffic except in fairly specific circumstances. :D

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That cannot be an emperical statement. Traffic engineers have absolutely wrecked the american city, largely be ause they didnt know the impact of adding lanes.

It's not the only reason. I think that traffic engineers lack/lacked a feel, a certain gut understanding , an inability to feel through the skin. Just look around you. See and hear them at municipal meetings. They are unable to sensually experience the effects of their work, their praxis.

I've spoken with traffic engineers before, and the consensus I've gotten is that, excusing a few bad apples, much of the problems originate with popular or political interference.

I believe it, but what's the point of having them then.

To do the best they can do within the confines of what's politically acceptable. There's an intersection near me that is just horrendous, but the engineer I talked to, who is now retired, said it was his mentor's task to fix it some 50 years ago. Actually fixing it, though, would require removing parking spaces, and the mayors have routinely vetoed that idea after they received pushback.

The people are to blame. You get what you vote for.

Who's to say they aren't the same as the developers implementing all the bad stuff at <pick your favorite hated tech company>? Listen to what they say, and plenty know it's bad, but they shrug their shoulders because that's what the bosses want and the pay is good.

But it will definitely improve, either speed or volume.

Locally. Under many circumstances. But always? That's not a universal law, as it's a part of a larger system that may perform more poorly if this leg provides more traffic.

This isn't categorically true either, the real world is delightfully complicated, far more so than you imagine. The way cars interact within a road, as they enter an exit the road, or how they choose their route can all create conditions where adding a lane only makes traffic worse and can reduce both speed and volume during peak traffic hours.

Check out the Downs-Thomson paradox.

I'm really bothered by the mindset of the people against this. People act like induced demand is evil.

In reality, if more people were able to go wherever they wanted to go, that's actually a good thing regardless of if the existing people didn't get to go somewhere faster.

Most people use roads to get to work. It's definitely not where they want to go.

It’s NIMBY in another form

I mean that was kind of my point, but judging by the responses I may have been too snarky.

Both the traffic engineer and the author of this blogpost are well-qualified enough in their fields of expertise to be careful about the claims that they make with regards to speed and efficiency.

A big issue is how those claims are interpreted by non-technical people, especially in leadership. Would hate for my CEO to stumble upon this blog post and believe, based on the title and a brief skimming, that his engineers just aren’t using AI correctly and that’s why the website still takes a few seconds to load its content.

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