Join 3,497 readers in helping fund MetaFilter (Hide)


The snow is almost like nature's tracing paper
February 4, 2014 7:04 PM   Subscribe

Desire paths [previously] show us where we want to walk. Snowy neckdowns, or "sneckdowns," show us where we don't need to drive.

Back in 2007 Streetfilms posted "Street Lessons from a Blizzard," and in 2011 "Snowy Neckdowns Redux," demonstrating that snowplows and the drivers that follow carve out paths that extend curbs at intersections, unintentionally making the streets safer for pedestrians through traffic calming.

A recent request for sneckdown spottings popularized a Twitter hashtag and brought reports from New York City, Philadelphia, Washington, D.C. and elsewhere. The concept has been expanded from curb extensions to include any undisturbed snowy areas that could be given over to pedestrians or, in better weather, green space.
posted by Knappster (22 comments total) 42 users marked this as a favorite

 
This is a great post. Useful and interesting. THanks!
posted by Miko at 7:59 PM on February 4


I'm with Miko, this is really cool.

Back when I was in university, I had a professor who had been at the school since it was founded. He helped to design the campus. When it came time to put in sidewalks, his committee wisely decided to delay for three years. By that time the students walking from from one building to another had worn down paths in the lawns, so they knew exactly where to lay the concrete. To this day, every sidewalk on that campus is useful. No wasted work.
posted by nushustu at 8:35 PM on February 4 [8 favorites]


They did this by us and the end result is a bunch of low curbs you can't see once it snows, no one knows exist and that scare the bejeesus out of everyone who drives over them. They did it in the fall. It snows a lot here.

It's a good idea in principle but if you're going to move the edges of the road and then cover the moved bits up in snow signpost it or something.
posted by fshgrl at 8:43 PM on February 4 [2 favorites]


My experience biking through all this (in Toronto) is that the neckdown phenomenon really puts the pinch on cyclists, forcing them and motor vehicles to share the road much more intimately.

It would be interesting to see this approached with bikes in mind as well. At first, I didn't care much for the idea of the new bike lane on Sherbourne St., but in practice, it really does a good job at mixing cars, bikes, and pedestrians (where I use it, anyway, it's varies a fair bit). Rather than "kerb extensions", an intermediate surface between sidewalk and roadway might be more versatile.

And yeah, using snow to graph traffic patterns is awesome.
posted by Casimir at 8:47 PM on February 4 [1 favorite]


using snow to graph traffic patterns is awesome.

But people drive very differently in the snow! If I'm driving on a snowy road with two lanes going my direction and the traffic has worn a path through the snow right in the middle of the lanes, then I'm going to drive on that path. But there's no way I'd drive that way if the snow were gone and it sure isn't any kind of proof that the road normally only needs to be one lane.
posted by straight at 9:58 PM on February 4 [12 favorites]


Great idea.
posted by carter at 10:00 PM on February 4


The difference in average (and peak) speeds between good weather and snowy driving would need to be accounted for as well, though of course in my ideal world people would drive slow all of the time. But as a general rule, tightening up intersections and making pedestrian paths shorter is a great approach.
posted by Dip Flash at 10:16 PM on February 4 [1 favorite]


But people drive very differently in the snow!

Yes, exactly. I read the first link, and it's loaded with question-begging. Wide turns is what you do on snow so you don't slide into the curb, but you don't need to do that on dry pavement.The overall assumption seems to be that patterns of driving when there's snow on the street indicate the space needed for driving at all times. This is wrong, because when it snows, a lot of people (including bicyclists) don't drive, so there's less vehicle traffic. It's as though they did a traffic study at 3 AM, and concluded there was excess capacity.
posted by Kirth Gerson at 5:15 AM on February 5 [2 favorites]


But people drive very differently in the snow!

Yes - more carefully. Which, in a dense pedestrian/parking area, is a great idea.

I think it's a great move in planning to actually slow traffic, increase inner-core congestion to the point of inconvenience, and make driving more of a pain in the ass in center zones. We should be incentivizing people to park and get out of their cars, not drive through the center of a populous town with walkers, bikes, pets and strollers everywhere.
posted by Miko at 5:32 AM on February 5 [6 favorites]


I agree. The primary focus of street design has been to flow the maximum amount of cars per hour, but that comes at the expense of pedestrian safety and vibrant street life. Deliberately creating minor traffic inefficiencies creates incentives towards other transportation modalities and acknowledges other road users as having legitimate rights to be there.

Where I live the public works department got some funding to narrow up several intersections, basically by building extensions at each sidewalk. The streets are way easier to cross on foot now, and as a driver it's much less ambiguous about right of way. I wish they had the money to do that on every intersection that doesn't have truck traffic that needs the wider turn radius.
posted by Dip Flash at 5:42 AM on February 5 [2 favorites]


The primary focus of street design has been to flow the maximum amount of cars per hour, but that comes at the expense of pedestrian safety and vibrant street life. Deliberately creating minor traffic inefficiencies creates incentives towards other transportation modalities and acknowledges other road users as having legitimate rights to be there.

Really well put. The driving patterns in the snow are (hopefully) just and indicator of what happens when cars have to deal with these "minor traffic inefficiencies", we can build them however we like.

Also, I agree that bicycles need to be considered when designing these. I feel like in NYC I've seen something similar (probably not a true "neckdown") where the bike path continued straight, so the pedestrian must first cross the (narrow) bike path, then cross the actual street.
posted by So You're Saying These Are Pants? at 7:26 AM on February 5 [2 favorites]


About a year or so ago they put those traffic calming bulges on one of the roads I use to go home. They included reflective warning signs that stick up. Probably 1/3 of the signs have already been knocked down.

It does at least discourage people from passing on the right shoulder like idiots.
posted by interplanetjanet at 8:04 AM on February 5


Kirth Gerson: "Wide turns is what you do on snow so you don't slide into the curb, but you don't need to do that on dry pavement."

Yes, generally the point of adding features like neckdowns is to force drivers to turn drive more carefully than they normally would on dry pavement. Check out this video of a woman being struck in a crosswalk when the van driver cuts the corner tightly instead of swinging out for a wider turn.
posted by coupdefoudre at 8:38 AM on February 5


The primary focus of street design has been to flow the maximum amount of cars per hour, but that comes at the expense of pedestrian safety and vibrant street life.

Worse still, it's designed to maximise the perceived maximum flow of cars per hour, so even car-flow maximising measures that seem counterintuitive (e.g. dropping lanes where traffic turns off instead of half a mile later) are vehemently opposed, so the road becomes nothing but an abyss of heavy stop-start traffic, which is no use to anyone.
posted by ambrosen at 11:19 AM on February 5


The way people drive in snow conditions isn't really the same as the way careful people drive in clear conditions, though. For one thing, as has been pointed out above, there are a whole lot fewer people on the roads in those conditions. We had a pretty big snowstorm last week, and the next day, the main roads were partially clear and the side roads, well, really weren't clear at all. The result was the usual volume of a clear day with the road restrictions laid in by snow (fewer lanes and alternate routes blocked by uncleared roads) and what we got was stop-and-crawl traffic, not safer conditions.

(Also nervous nellies who were constantly slamming on their brakes when they came on a less cleared spot instead of, you know, just going a little slower in the first place.)
posted by Karmakaze at 1:34 PM on February 5


hat we got was stop-and-crawl traffic, not safer conditions.

That is safer for pedestrians than high-speed traffic.

But in addition to safety, this also reveals interesting places where green space could exist.
posted by Miko at 1:56 PM on February 5


I'm all for people driving slower and more carefully, but I'm not really sold on this idea. It seems like the idea is just to restrict traffic flow on the basis that the restrictions appear naturally when it snows and the plows pile the snow up at the corners of intersections? I feel like the patterns they're seeing in the snow are just drivers reacting cautiously to unusual and sub-optimal driving conditions; that doesn't automatically mean that those driving patterns are better under normal circumstances. I mean, it might or it might not. If the plows piled up the snow in front of everyone's driveways, thus preventing anyone from using their cars at all, would it follow that the best thing to do is put jersey barriers in front of those driveways, so that cars would be similarly blocked all year round?

Basically, this is junk science. I get that it's hard to run a controlled experiment in road design, but that doesn't mean that you can just extrapolate from anecdotal observations of an unusual situation into a general prescription for traffic infrastructure. If you want to see whether "neckdowns" are a good idea or not, you need to look at cities that do and do not use them, try to subtract out the effects of other differences between those cities, and then decide which system gives better results. And you need to look at all the results and make a decision based on net cost/benefit, not just a single cherry-picked variable like average traffic speed or even collision rates. You're free to decide which variables are most important to you, but you can't pretend that your pet statistic exists in a vacuum.

This article is just an example of someone's confirmation bias leading them to find validation for a theory that they've already decided is correct. Doing science on social policy and infrastructure design is hard, and perfect experiments may be impossible, but people can and do manage it anyway. The conclusions aren't always super solid by the standards of the natural sciences, but if the work is done carefully they're still a heck of a lot better than nothing, and the practice is worth supporting and worth basing decisions on. This article isn't that, and I hope nobody in a decision-making position takes it seriously.
posted by Scientist at 3:13 PM on February 5


. If you want to see whether "neckdowns" are a good idea or not, you need to look at cities that do and do not use them,

Right, so I am fairly sure that's already been done and been pretty solidly proven, which is why creating them - and other traffic-calming features like painting fake "pedestrian refuge" islands and medians onto roadways - has become more and more prevalent over the last decade (for instance, "Neckdowns have reduced overall severity rates in four out of six surveyed areas in New York City. In two of three locations, they reduced the injury severity when a vehicle does crash into a pedestrian. This is attributed to the fact that the neckdown limits the spaceavailable for undisciplined driving and subsequent vehicle speed.") This particular set of links is about using snow to note places that additional such research-support and world-tested measures could be deployed, and aren't yet.
posted by Miko at 3:49 PM on February 5 [2 favorites]


My experience biking through all this (in Toronto) is that the neckdown phenomenon really puts the pinch on cyclists, forcing them and motor vehicles to share the road much more intimately.

The presence of sufficient ice and snow on the roads to require snowplows may put a pinch on cyclists, like pinched between the undercarriage of a vehicle and the road.

Two wheeled vehicles are unstable on low-friction surfaces like ice and snow. This makes you a traffic menace to stable vehicles with three or more wheels.

Put your bike away until spring.
posted by charlie don't surf at 5:56 PM on February 5


Never! Just get one of these.
posted by Miko at 7:47 PM on February 5


PHOTOS: What Snow Tells Us About Creating Better Public Spaces on E. Passyunk Avenue

The author apparently ignores the signs of vehicles turning through the snow, focusing on creating as much extension of pedestrian space as possible.
posted by the man of twists and turns at 8:50 AM on February 7


That's a weird interpretation. He's not ignoring them, he's noting how many fewer vehicles make that turn than don't, because of the persistence of snow in those unplowed, unmelted locations. I know that area a little and it's a warren of side streets on which there's little traffic except for people going to and returning from their residences. Do they really need so much room devoted to cars? Probably not, is the point. He's looking at the difference between where the large majority of traffic goes and where a few outliers have gone. The outliers probably don't need to be designed around.

That triangle in front of Geno's Steaks should definitely be a small pedestrian plaza. On a summer night that is full of a line of people who are being forced to stand in the street. The traffic is one-way right there so there's no need to turn from one of those streets onto the other.
posted by Miko at 9:53 AM on February 7


« Older The Empathy Exams: Acting out pain until that pain...  |  The state of ebony... Newer »


This thread has been archived and is closed to new comments