I've seen one instance where homeowners in the neighborhood vetoed a proposal to have a centerline painted on a broad street through the neighborhood. Total width was probably about 3 lanes, and many people used it as a "cut through", and going pretty fast. However, painting a centerline would have made property values go down, the homeowners argued, as that would have meant that the street was no longer a residential low-traffic street.

Studies have shown that traffic is slower on roads without lines. If your goal is to slow down traffic you don't want a line.

Conversely, painting lines, and narrowing the "american standard" lane width will slow drivers down, as the more narrow lane makes drivers feel like they are going faster. http://www.ncbi.nlm.nih.gov/pubmed/14668160 http://nacto.org/publication/urban-street-design-guide/stree...

Of course it also makes collisions more likely at a given speed because there is less margin for error in estimating how much space you need on either side of your vehicle.

I still can't understand this logic of "let's make the roads safer by making them more dangerous" as if the only factor is how fast people are going. Wouldn't it be better to make roads that are safe at the speeds people want to drive? Build sidewalks so pedestrians don't have to be walking in the street etc., and let bicycles use them because a bicyclist is clearly more like a pedestrian than a car?

Have you looked at any studies, many point to wider lanes being more dangerous because people drive faster on them. Don't just assume that 'wider == safer' without any data.

http://usa.streetsblog.org/2015/05/27/compelling-evidence-th...

The flaw is thinking that the improvement comes for free. You're basically gaming human behavior. The narrower lanes eat most of the safety improvement of people driving slower. You only get the tiny bit that was left over by mistake because people slightly overcompensate for the danger you put them in.

But to get that tiny bit you're still paying the entire cost of slowing vehicles down. It takes longer to get where you're going, including for emergency vehicles. The most fuel efficient cruising speed for most vehicles is at or above 40MPH, which you're diverging from.

You're paying full costs for fractional benefits. You would be better off putting some cops on the side of the road with an EMP cannon to disable any cars that show up. Sure, it sounds crazy, but it improves safety by slowing people down so we should do it, right?

Except that there are other, better ways to improve safety. Like building sidewalks, and making sure there is enough capacity on the highways that people don't come down to surface streets to avoid it, and improving mass transit so there aren't as many people driving to begin with.

Making the lane more narrow does not have to equal putting two lanes of opposing traffic closer together. We can make the dividing line(s) wider to compensate. To wit, this conversation revolves around residential neighborhoods, where cars frequently park on the street, where the speed limit is likely not 40MPH. Making the lanes narrow is meant to get people to follow the speed limits, I'd say at 30MPH or less.

> Making the lane more narrow does not have to equal putting two lanes of opposing traffic closer together. We can make the dividing line(s) wider to compensate.

And now you're doing something different than the data and will plausibly get a different outcome. If the opposing traffic is not closer together then maybe people don't slow down as much or at all anymore. And you're pushing the cars closer to the pedestrians.

> To wit, this conversation revolves around residential neighborhoods, where cars frequently park on the street, where the speed limit is likely not 40MPH.

Yet that may nonetheless be the prevailing traffic speed, and the speed that emergency vehicles can reasonably travel when not impeded by "traffic calming" measures. That you didn't expect people to get the efficiency you're taking away from them doesn't mean you aren't taking it away. Moreover, fuel efficiency is a curve with an inflection point somewhere above 40MPH. That means 40 is better than 30, but it also means 35 is better than 25 and 30 is better than 20.

> Making the lanes narrow is meant to get people to follow the speed limits, I'd say at 30MPH or less.

Except that the speed limit is generally supposed to be set at the 85th percentile traffic speed (and is generally set ~10MPH below that for reasons of politics and revenue generation), so slowing down traffic will lead to a reduction in the speed limit.

Admittedly, he claimed only "for a given speed" so that's a different point, albeit probably the more important one.

Ah, I was not aware of it.

Centerlines encourage faster driving, so lately the fashion is to remove them where possible.

One trick that I discovered was to hang not a sign, but simply something that looks like a high-visibility jacket. Drivers for a half second think it's might be a cop doing speed enforcement and slow down. I remember while at university seeing people slow because of an orange garbage garbage caught in a hedge 400m away. That bag was better at enforcing the speed limit than photo radar.

One of my parents neighbors took this a step further -- he bought a surplus blue Crown Vic, put a yellow day glow strip on one side and parked it on his land near the curb.

At a glance, it looked like a state police cruiser.

I once saw a full-size, flat plastic dummy that looked like a police car from the side. Slowed everybody down too. It was only clear it was a dummy as you passed it.

These "if it saves just ONE CHILD" arguments can often be clarified with hard data. How many accidents have occurred to date due to excessive speed on the blind curve?

If the answer is zero, and the curve otherwise meets traffic-engineering best practices, well... stop whining.

If the answer is nonzero, maybe there's a solution other than putting up unnecessary stop signs that will just discourage respect for traffic laws in general.

But we don't have enough data to say for sure in this thread, and emotional appeals don't help at all.