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Why 12-Foot Traffic Lanes Are Disastrous for Safety

258 points by mortenjorck 12y ago

jdipierro 12y ago
I just rolled out a measuring tape to 12 feet and I'm quite certain my local traffic lanes are nowhere near there..
- Zigurd 12y ago
  Did you know that two basketballs fit, side by side, through a basketball hoop? Eyeballing things like this is almost never close to right.
  - SkyAtWork 12y ago
    You can probably cram them through since they are flexible, but they wouldn't fit without some force; a regulation rim is 18 inches inside diameter and a basketball 9.5 inches diameter.
    - Zigurd 12y ago
      Good catch. I saw this demonstrated in grade school, where they were probably using size 6 balls. Nevertheless, most people think it's not even close.
gohrt 12y ago
The article has 1.2 the amount of words it needs, at least. Apropos. Strange to use Florida as an example, with an 8-lane local road! Suburban Florida is empty and flat very spread out and every road is basically a highway. People need to go fast because everything is far away. Not like urban environments where most time is spent stopped at corners, not moving.
- vonmoltke 12y ago
  Your statement is not applicable to West Palm Beach or any other locale along the Gold Coast. That area has some of the densest population in the US.
  - JoshTheGeek 12y ago
    Agreed. Tampa, Orlando, and the other big cities are like any others. In the middle of the state or the Everglades, though, you can go miles without even a turnoff.
kenjackson 12y ago
How does traffic speed increase with wider lanes, but capacity doesn't? How many lives are saved by fire trucks, police, etc... being able to get to/from emergencies more quickly? I feel like experimental data will be much more useful than models to measure the impact of 10' to 12' lanes.
- to3m 12y ago
  I would imagine that fire engines and the like will rely more on traffic getting out of their way than on greater overall throughput.
- eridius 12y ago
  These are city streets. Capacity is probably limited by the rate at which cars go through traffic lights (which is probably largely unchanged by 10 vs 12 feet lanes), not by how fast a motorist can accelerate when driving away from a light.
- slyall 12y ago
  I read a story just recently that suggested that suggested that since areas with wider lanes have lower density any speedups of emergency vehicles is lost because they one average have to travel a greater distance. I can't find the original story but here are some papers: "The findings show that the density and age of a residential area or jurisdiction explain some of the variation in average EMS response times between urban and suburban or exurban locations. Holding other things constant, those who live in more sparsely settled and newer developments tend to have longer wait times for EMS." http://www.jstor.org/discover/10.2307/25469783?uid=3738776&uid=2&uid=4&sid=21104886088563 http://www.jstor.org/discover/10.2307/25469783?uid=3738776&u... http://www.cues.fau.edu/cnu/docs/Ex-Urban_Sprawl_as_a_Factor_in_Traffic_Fatalities_and_EMS_Response_Times_in_the_SE_US-Lambert-Meyer.pdf http://www.cues.fau.edu/cnu/docs/Ex-Urban_Sprawl_as_a_Factor...
- julespitt 12y ago
  When speed increases, the safe distance between cars increases as well, therefore reducing overall throughput.
wozniacki 12y ago
Apples to apples, this does not really apply to SF or even most of the Bay Area. Perhaps all of Texas, Arizona or NM. Not here. I hope some smart Alec SF supe does not get any ideas, reading this. The bulb-outs at the intersections [1], the rules-dont-apply-to-us cyclists [2], the abundance of parklets and dedicated Muni lanes are already making driving in SF a hugely cumbersome affair. If it isn't already, with its 20%+ grade roads [3]. From my experience living in SF, drivers here are not the most skilled as it is. This will only worsen things. If Mr. Wiener catches wind of this, I'm certain he will call for miniature lanes, like when he called for miniature firetrucks, when firefighters expressed concern over the width of streets. [4] [1] http://sf.streetsblog.org/2014/07/03/bulb-outs-noe-valleys-getting-them-outer-balboas-got-them/ http://sf.streetsblog.org/2014/07/03/bulb-outs-noe-valleys-g... [2] http://www.sfgate.com/crime/article/Bicyclist-sentenced-for-fatal-S-F-crash-4736312.php http://www.sfgate.com/crime/article/Bicyclist-sentenced-for-... [3] http://www.datapointed.net/2009/11/the-steeps-of-san-francisco/ http://www.datapointed.net/2009/11/the-steeps-of-san-francis... [4] http://sf.streetsblog.org/2014/05/09/monday-speak-out-on-sffds-push-for-wider-streets-at-city-hall/ http://sf.streetsblog.org/2014/05/09/monday-speak-out-on-sff...
- to3m 12y ago
  I've already read that story about that cyclist who killed a man. Do you have 2 different ones?
  - wozniacki 12y ago
    Here's a TV news report on the incident: http://www.youtube.com/watch?v=2EQA_Cm8SKw http://www.youtube.com/watch?v=2EQA_Cm8SKw
    - to3m 12y ago
      Thanks! This appears to be the same guy though.
      - wozniacki 12y ago
        Geez! Have you noticed the downvote parade? Have I said something mildly offensive to the sensibilities of the Critical Mass militia?
robomartin 12y ago
Blah. I remember when the speed limit was raised from 55 to 65. Politicians paraded all kinds of studies from engineers, PhD's and mothers crying on TV. The claim was that blood would run down our streets and highways. The effects of making this change, the "experts" and politicians said, would be cataclysmic. What happened in reality? Nothing of the sort. Actually, some of the opposite. Accident and fatality rates went down. So I call hogwash. Maybe this guy has some sort of bias, financial or political interest in this idea. Maybe it is about hiring a million new union workers across the nation to repaint all of our streets and buy votes for the democratic party in 2016. Maybe it is about giving a few huge corporations juicy contracts to try to buy financial support and votes for republicans. I don't know. My life is about science and data. So, yes, I do value honest studies with solid data and conclusions. I also know that you can't take a sentence or two our of a study and quote it completely out of context to support your case. When put into context the reality of the study could be very different and the conclusions could be really flawed. Ask almost anyone who drove pre-65mph how they feel about the change to 65. I would be surprised if anyone said it got worst. It's a lot more relaxed. You don't have to be constantly focused on the darn speedometer or become a human highway patrol detector. In fact, I think the speed limit ought to be raised to 80mph. People are not suicidal. They'll drive at whatever speed is safe and comfortable for them. On average, today, that seems to be somewhere around 75 to 80mph, except when CHP gets on the road and everything slows down causing traffic backups, etc. If we are really that concerned that blood will run down streets it is a relatively simple technological matter to legislate that no automobile sold in the US can go faster than, say, 70mph. An automatic speed limiting system could also be put into place to limit speeds everywhere in real time. A low power emitter in every traffic signal in the nation could tell cars what the max speed limit might be and the software in the car keeps you from exceeding it. Done deal. If the issue is so serious let's just do that. I'd rather have cops devote their time to chasing bad guys than hiding behind a fence to give dumb traffic tickets to all the mommies taking their kids to school during the first week of class (happens almost every year here).
- revelation 12y ago
  Blood is running down the streets (just not literally). Traffic deaths are the top killer for kids under 15 in NYC; these aren't even people driving! They are killed by others, and often at speeds that are very, very likely to kill upon basically any collision. If you value science and data, you can tell from a mile what an enormously stupid idea it is to have multi-ton cars roaming cities at even 20mph. Physics tells us it's deadly, everything tells us people are incompetent and unfit to drive, and the statistics bear out the very, very high expected costs. I'd argue it can only be ignorance that would make you look at the tremendous body of evidence, both theorethically and statistically, and conclude > People are not suicidal. They'll drive at whatever speed is safe and comfortable for them.
lorddoig 12y ago
The standard of the average academic/research paper is low enough that very few stand on their own. This, of course, is the reason why certain media outlets are able to make lots of money with bi-weekly, likely untrue claims that <insert thing here> "causes cancer". This article repeats some conclusions from various research efforts of unknown (to me) quality, most of which carry caveats, and none of which were titled "Effects of Lane Width on Pedestrian Safety: A Quantitative View". These weak (not pejorative, just opposed to strong) statements are then used as the base assumptions atop which a logical argument is constructed - an argument that is incomplete. The relationship between speed and mortality is only attacked from the perspective of what happens once a collision has taken place, for instance, but there will likely also be a relationship between speed and the level of caution exercised by pedestrians, but no evidence about this is presented. This is a question in need of comprehensive study; the tidbits presented here are neither strong nor complete enough to say anything absolute, much less accuse anyone of having blood on their hands. Personally, I think such a study would validate much of what the author feels. But it is only my gut that says that, I'd need a study to "know". As such this comment is not meant as a criticism of the author or the thoughts in the article, but more as a sort-of defensive reminder of what the scientific method means.
- andrewliebchen 12y ago
  You wrote this from your car, didn't you?
- kentonv 12y ago
  Another thing missing: What is the economic cost of slowing everyone down? Clearly if people spend 50% longer commuting because they're driving 20mph instead of 30mph, that has real consequences for both their economic output and quality of life (commute time has a surprisingly large impact on a person's overall happiness!). The author disregards this factor entirely. I've seen this pattern in a number of "unintuitive and seemingly clever" traffic engineering tricks proposed in recent years. For example, it has been shown that removing all traffic signs can in fact improve safety -- again by slowing everyone down. Another similar point (mentioned in the article) is that expanding freeways doesn't reduce congestion, because the new lanes are filled quickly. The argument is, apparently, that we therefore should not bother expanding freeways. The argument ignores the fact that the expanded freeway is serving many more people, creating immense value even if the speed of traffic hasn't improved. (For the trolls: I personally take the train rather than drive whenever possible.)
AnthonyMouse 12y ago
> as state DOTs widen highways to reduce congestion, in complete ignorance of all the data proving that new lanes will be clogged by the new drivers that they invite. Let's see a cite to that data, because it seems ridiculous. Obviously if you make a road less congested people may start preferring it to other, more congested roads, but that just means the reduction in congestion is distributed rather than concentrated, and how is that a bad thing? The entire premise of this article is questionable. The theory is that people will drive more carefully when the roads are more dangerous. From this the argument is that we should make the roads more dangerous in order to make them safer. This is obviously completely counterintuitive so they point to some evidence that it could be true (which itself seems to imply that its veracity lies near the statistical margin of error). The real problem is that it's a false dichotomy. Making the roads more dangerous is not the only way to make people drive more carefully. And alternative ways of encouraging people to drive more carefully are obviously preferable to a method that, at a given speed and level of care, is more dangerous according to the laws of physics. More than that, this “make the roads dangerous to make them safe” is completely backwards when we're on the verge of commercially available self-driving cars. A self-driving car is obviously not bound by human psychology, so for all of those vehicles, making the roads more dangerous will only make the roads more dangerous.
- joshfraser 12y ago
  There's actually a ton of data to support the idea that making activities feel more dangerous makes them safer. I actually gave a talk on this topic a few years ago: http://www.onlineaspect.com/2010/07/05/ignite-boulder-11/ http://www.onlineaspect.com/2010/07/05/ignite-boulder-11/ How to Live Dangerously by Warwick Cairns is a great book on the topic as well.
  - AnthonyMouse 12y ago
    > There's actually a ton of data to support the idea that making activities feel more dangerous makes them safer. I'm not disputing the idea that people might respond to perceived safety by taking more risks or vice versa. It's almost a corollary to the efficient market hypothesis. However, that doesn't tell you anything about whether they will overcompensate or undercompensate in any given context. And what I'm really objecting to is the idea that we should make people "feel" less safe by doing things that actually make them less safe if not for people [over]compensating for them. Because that's a very dangerous game if you're wrong and it's completely ignoring the possibility of solving the problem in other ways, which should on balance be more effective because you aren't running the wrong way with the ball.
chetanahuja 12y ago
I'm seeing a lot of resistance to the idea of narrower city streets on this thread. The advantages of narrower city streets (and hence, crossings) goes far beyond safety. It actually enhances quality of life in a significant way. A wide, four lane highway running across your town basically says humans must come encased inside an automobile. Pedestrians and cyclists become second class citizens. It's a design driven for the convenience of cars and to the detriment of humans. Here's a far more engaging critique of car-first design by James Kunstler: http://youtu.be/Q1ZeXnmDZMQ http://youtu.be/Q1ZeXnmDZMQ
- cordite 12y ago
  The university I went to invested in skywalks to replace many if almost all cross walks within and on the edges of campus. It does require more energy to go up and down sometimes, but it means everyone is safer and everything still flows.
  - icebraining 12y ago
    How does it work for people with reduced mobility, wheelchairs, etc?
    - cordite 12y ago
      It is a spiral with an acceptable grading with rails.
  - arthurdenture 12y ago
    The big problem with skywalks is that they result in the streets underneath them being empty (of pedestrians). This has downsides: - Empty streets feel less safe - Stores get less foot traffic - Cars are more likely to speed when there's no one walking about So they really can suck the life out of the street.
    - Dylan16807 12y ago
      Elevate the stores.
jff 12y ago
Ah, the old "If I don't wear a helmet, I'll ride more cautiously and never get into a wreck" argument.
- megablast 12y ago
  There is an argument that car drivers are more careful when they see cyclists not wearing helmets. And also the overall health benefits are better, when you consider that more people will ride without helmet rules. Only Australia has this requirement.
  - jff 12y ago
    Crap, I was talking about motorcyclists, but didn't specify it in my post. This is literally an argument I have heard from other riders.
capcah 12y ago
I see a huge number of comments on this thread implying that carefulness is related to the road danger. It's the perceived danger that matters. You don't need to make the roads more dangerous, just need to make them look so. I'm not from USA, and on the last time I visited it, I noticed how recklessly people drive on the highways, most of them were on the phone, eating, or doing something else(there was even a lady fixing her hair with her right hand, talking on the cellphone with her left hand and holding the steering wheel with her elbow, that freaked me out). If those people behave the same driving on a street, I can see that being the cause of the majority of accidents, since the reaction time for events will be smaller, since most occurrences happen within a few meters of the car. Finally, I know that this is not the focus of the article, but the USA cities need to focus more on the people that either cannot or will not(like me) drive. LA, LV and Miami, for instance, were pretty hellish until I finally gave in and rented a car, with poor public transportation and pedestrian access.
- click170 12y ago
  I'm frequently surprised by the lack of sidewalks everywhere outside of the downtown core of many cities. Perhaps its different in cities I haven't been to, but compared to where I grew up in, it does seem like everywhere else is car-first. Its not just the states or even big cities, I've lived in a small town in Ontario that was similar. It makes me wonder if its related to the age of the area. Newer areas seem to have more sidewalks.
  - marcus_holmes 12y ago
    I visited San Diego (I was living in the UK at the time, and found it impossible to get anywhere. I was routinely told that only poor people caught the bus (and it could be dangerous), and there were no pavements anywhere to walk on. I walked to the nearest burger place for lunch every day, a hellish 1-mile jaunt through rubbish-strewn wasteland getting beeped at every time I tried to cross a road. In contrast, every European and Australian city I've lived in has catered for pedestrians and cyclists to the extent that it's at least possible to walk or bike anywhere you need to go (even if it would take hours in these huge Aussie cities). I still wonder at it. How do Americans feel about living in such a shitty environment?
nashashmi 12y ago
This article completely misses the point of having wider lane path ways. Wider lanes help increase the speeds of vehicles and studies have shown that high speed traffic works far better than slow traffic. Just look up ramp metering where they deliberately keep too much traffic off of highways to maintain speed and maintain safety and maintain efficiency of roads. The cases where narrow street widths work better are places where there is more stop and go traffic like downtown areas where majority of the residences are crowded with store-front development. There instead of insisting on narrow lanes, you should insist on complete street designs that appropriately designs for all kinds of traffic. New urbanist movements seem to be behind this kind of lunacy of trying to create traffic conditions more difficult for cars. In New York, this trend has been set of by the Bloomberg administration and is labeled/marketed as traffic calming. It is really traffic impeding and is the center piece design of urban environments. I admit there are various benefits to it, but the underlying motivations are to be anti-gas guzzling vehicles.
- nowarninglabel 12y ago
  You should re-read the article. He specifically states he is no talking about highways, and further specifically states that throughput of traffic remains the same in areas with 10-ft lanes, and gives references to prove that.
- ploxiln 12y ago
  Your comment makes me think about this a bit differently. I live in NYC, and end up driving through it once every couple of months. While I'm normally sympathetic to people who hate anything that makes things easier for drivers and worse for pedestrians, if NYC is a model for "traffic calming", it's terrible, because I'm very angry and aggressive after 15 minutes of trying to drive in this place. I don't want to drive often, and I don't want to encourage more driving, but I want driving to be less difficult. Maybe make street parking 2-hour-max everywhere so there's room for cars and trucks to stop so they don't stop in the middle of the road, and they're forced to pay for off-road parking overnight, etc. Or something else, I don't know. That sounds severe, but the situation is already ridiculous.
  - 12y ago
phkahler 12y ago
Even if I agree with most of that, I don't think keeping the road wide and using the outside area a bike lanes will work. People are going to see a wide road and drive fast anyway. I suspect you'd have to actually narrow the road, not just reallocate the concrete. But TD;DR maybe that was covered and I'm wrong.
- raquo 12y ago
  Anecdotally, in Vancouver we have narrow lanes in the city, with many streets having all kinds of bike lanes along their sides – both shared and separated. It works quite well, especially the separated ones. Narrow lanes surely do decrease average driving speed, it's damn uncomfortable to drive fast in traffic, and staying in the lane requires more concentration. I do miss wide Russian lanes sometimes, but the narrow ones are undeniably safer.
  - mytochar 12y ago
    Separated bike lanes are absolutely wonderful. More of those and I would probably ride my bike more places.
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swartkrans 12y ago
This article makes me genuinely angry for burying the explanation for why 12 foot traffic lanes are dangerous beneath many paragraphs of what the author clearly thought must have been clever banter, wasting my time. Note to authors: put the claim and the gist at the top, then defend it with more details. Don't burry the gist of the article with shitty and annoying writing, making the reader scan paragraph after paragraph of bullshit to establish if the article is worth reading in the first place. In this case, it wasn't.
- rando289 12y ago
  Ya, and what about the people like me who gave up on that scanning and came here to find the tldr, but instead just found your complaint, and then read this complaint about the complaint!! When will it end?!
- dalke 12y ago
  Your anger should be directed to the person who linked to the site, and not to the author. The information you want is available at http://nacto.org/docs/usdg/lane_widths_on_safety_and_capacity_petritsch.pdf http://nacto.org/docs/usdg/lane_widths_on_safety_and_capacit... and in exactly the format that you want. Indeed, this is the source material for the article that you are angry about, as was cited in the text. The author wrote the article for people who want to read "shitty and annoying writing". There's enough of that writing in the world to know that those readers are in the majority. Those people also need convincing, don't they?
slashnull 12y ago
Please god of good urban planning give the force to Street Art the tagline "BUILD NARROW STREETS" everywhere
CodeWriter23 12y ago
About 8 or 9 months ago, they reduced the 3-lane thoroughfare through my part of town to 2-lanes with a bike lane, and narrowed the lanes to about 10 feet. People slowed down at first, but now people go just as fast as they used to, typically 5-10MPH over the speed limit, and some 15 MPH over (that's 50MPH). The radar signs installed as part of the project always read 40, 42, 45 and not just for my car. As a cyclist, the bike lanes don't really make me feel safer. There is a good margin of space between the bike lane and the car lane, but the bike lanes are really only in effect for half of any given block. The second half of the block, the line between the car/bike lanes is dotted, and cars can legally enter the bike lane, to make right turns. And then of course, anyone parallel parking on the street has to cross the bike lane to do so. Making the lanes narrower did not make pedestrian crossings any safer, as the road is actually the same width, and you still have to travel the same distance to cross the street. What did make it safer for pedestrians, the installation of flashing yellow warning lights at certain crosswalks, that pedestrians can turn on before crossing the street. Motorists see them and stop for people crossing, and that is a new and welcome effect. The bike lanes would have been much MUCH better implemented one block south of the main drag on a residential street that runs parallel. Much safer for cyclists. Healthier too, not having to breath as much vehicle exhaust. And probably a more optimal allocation of resources for the citizens. As much as everyone wants to be PC and become friendly advocates of human-powered transport, it really doesn't make sense in this part of town, to increase trip times and emissions for thousands of motorists daily, so the 50 people who choose to ride their bike can have a marginally safer lane to ride in. In Downtown L.A., it is completely different. Downtown, the bike lanes make sense because hundreds if not thousands of people use them. You always see a bike in the bike lane over there. But outside of the heart of the city, many people commute to work and carpool their kids to school and ballet and such. They're not going to ride bikes 5 hours a day to make that kind of commute. Oh, and where the traffic engineers failed to account for, and accommodate heavy traffic on a couple of heavily-traveled segments of the road, motorists now drive their cars illegally in the bike lanes during periods of congestion. IMO the project is mostly a failure. The safer pedestrian crossings are a great improvement. But the bike lanes such as they are, and the narrower lanes, just a waste of money. Putting the bike lanes on a side street would have been really great, a win-win for both cyclists and motorists.
- 12y ago
jchrisa 12y ago
This article just came out last night, suggesting that road diets are great bang for the buck when it comes to decreasing crashes. http://bikeportland.org/2014/10/10/less-500000-three-road-diets-preventing-37-crashes-every-year-112049 http://bikeportland.org/2014/10/10/less-500000-three-road-di...
- CamperBob2 12y ago
  At some point, people forget what the roads are for in the first place. You can also decrease crashes by enforcing a 5 MPH speed limit, right?
zenciadam 12y ago
If you're really interested in the subject and want to read more without dealing with the wanky blogger writing style check out "Traffic: Why We Drive the Way We Do" (http://www.amazon.com/Traffic-Drive-What-Says-About/dp/0307277194/ http://www.amazon.com/Traffic-Drive-What-Says-About/dp/03072...).
tdurden 12y ago
Seinfeld warned us of the danger of wide lanes quite a while ago : https://www.youtube.com/watch?v=CwinnODU0yo https://www.youtube.com/watch?v=CwinnODU0yo

258 points by mortenjorck 12y ago

jdipierro 12y ago

I just rolled out a measuring tape to 12 feet and I'm quite certain my local traffic lanes are nowhere near there..

Zigurd 12y ago
Did you know that two basketballs fit, side by side, through a basketball hoop? Eyeballing things like this is almost never close to right.
- SkyAtWork 12y ago
  You can probably cram them through since they are flexible, but they wouldn't fit without some force; a regulation rim is 18 inches inside diameter and a basketball 9.5 inches diameter.
  - Zigurd 12y ago
    Good catch. I saw this demonstrated in grade school, where they were probably using size 6 balls. Nevertheless, most people think it's not even close.

gohrt 12y ago

The article has 1.2 the amount of words it needs, at least. Apropos. Strange to use Florida as an example, with an 8-lane local road! Suburban Florida is empty and flat very spread out and every road is basically a highway. People need to go fast because everything is far away. Not like urban environments where most time is spent stopped at corners, not moving.

vonmoltke 12y ago
Your statement is not applicable to West Palm Beach or any other locale along the Gold Coast. That area has some of the densest population in the US.
- JoshTheGeek 12y ago
  Agreed. Tampa, Orlando, and the other big cities are like any others. In the middle of the state or the Everglades, though, you can go miles without even a turnoff.

kenjackson 12y ago

How does traffic speed increase with wider lanes, but capacity doesn't? How many lives are saved by fire trucks, police, etc... being able to get to/from emergencies more quickly? I feel like experimental data will be much more useful than models to measure the impact of 10' to 12' lanes.

to3m 12y ago
I would imagine that fire engines and the like will rely more on traffic getting out of their way than on greater overall throughput.
eridius 12y ago
These are city streets. Capacity is probably limited by the rate at which cars go through traffic lights (which is probably largely unchanged by 10 vs 12 feet lanes), not by how fast a motorist can accelerate when driving away from a light.
slyall 12y ago
I read a story just recently that suggested that suggested that since areas with wider lanes have lower density any speedups of emergency vehicles is lost because they one average have to travel a greater distance. I can't find the original story but here are some papers: "The findings show that the density and age of a residential area or jurisdiction explain some of the variation in average EMS response times between urban and suburban or exurban locations. Holding other things constant, those who live in more sparsely settled and newer developments tend to have longer wait times for EMS." http://www.jstor.org/discover/10.2307/25469783?uid=3738776&uid=2&uid=4&sid=21104886088563 http://www.jstor.org/discover/10.2307/25469783?uid=3738776&u... http://www.cues.fau.edu/cnu/docs/Ex-Urban_Sprawl_as_a_Factor_in_Traffic_Fatalities_and_EMS_Response_Times_in_the_SE_US-Lambert-Meyer.pdf http://www.cues.fau.edu/cnu/docs/Ex-Urban_Sprawl_as_a_Factor...
julespitt 12y ago
When speed increases, the safe distance between cars increases as well, therefore reducing overall throughput.

wozniacki 12y ago

Apples to apples, this does not really apply to SF or even most of the Bay Area. Perhaps all of Texas, Arizona or NM. Not here. I hope some smart Alec SF supe does not get any ideas, reading this. The bulb-outs at the intersections [1], the rules-dont-apply-to-us cyclists [2], the abundance of parklets and dedicated Muni lanes are already making driving in SF a hugely cumbersome affair. If it isn't already, with its 20%+ grade roads [3]. From my experience living in SF, drivers here are not the most skilled as it is. This will only worsen things. If Mr. Wiener catches wind of this, I'm certain he will call for miniature lanes, like when he called for miniature firetrucks, when firefighters expressed concern over the width of streets. [4] [1] http://sf.streetsblog.org/2014/07/03/bulb-outs-noe-valleys-getting-them-outer-balboas-got-them/ http://sf.streetsblog.org/2014/07/03/bulb-outs-noe-valleys-g... [2] http://www.sfgate.com/crime/article/Bicyclist-sentenced-for-fatal-S-F-crash-4736312.php http://www.sfgate.com/crime/article/Bicyclist-sentenced-for-... [3] http://www.datapointed.net/2009/11/the-steeps-of-san-francisco/ http://www.datapointed.net/2009/11/the-steeps-of-san-francis... [4] http://sf.streetsblog.org/2014/05/09/monday-speak-out-on-sffds-push-for-wider-streets-at-city-hall/ http://sf.streetsblog.org/2014/05/09/monday-speak-out-on-sff...

to3m 12y ago
I've already read that story about that cyclist who killed a man. Do you have 2 different ones?
- wozniacki 12y ago
  Here's a TV news report on the incident: http://www.youtube.com/watch?v=2EQA_Cm8SKw http://www.youtube.com/watch?v=2EQA_Cm8SKw
  - to3m 12y ago
    Thanks! This appears to be the same guy though.
    - wozniacki 12y ago
      Geez! Have you noticed the downvote parade? Have I said something mildly offensive to the sensibilities of the Critical Mass militia?

robomartin 12y ago

Blah. I remember when the speed limit was raised from 55 to 65. Politicians paraded all kinds of studies from engineers, PhD's and mothers crying on TV. The claim was that blood would run down our streets and highways. The effects of making this change, the "experts" and politicians said, would be cataclysmic. What happened in reality? Nothing of the sort. Actually, some of the opposite. Accident and fatality rates went down. So I call hogwash. Maybe this guy has some sort of bias, financial or political interest in this idea. Maybe it is about hiring a million new union workers across the nation to repaint all of our streets and buy votes for the democratic party in 2016. Maybe it is about giving a few huge corporations juicy contracts to try to buy financial support and votes for republicans. I don't know. My life is about science and data. So, yes, I do value honest studies with solid data and conclusions. I also know that you can't take a sentence or two our of a study and quote it completely out of context to support your case. When put into context the reality of the study could be very different and the conclusions could be really flawed. Ask almost anyone who drove pre-65mph how they feel about the change to 65. I would be surprised if anyone said it got worst. It's a lot more relaxed. You don't have to be constantly focused on the darn speedometer or become a human highway patrol detector. In fact, I think the speed limit ought to be raised to 80mph. People are not suicidal. They'll drive at whatever speed is safe and comfortable for them. On average, today, that seems to be somewhere around 75 to 80mph, except when CHP gets on the road and everything slows down causing traffic backups, etc. If we are really that concerned that blood will run down streets it is a relatively simple technological matter to legislate that no automobile sold in the US can go faster than, say, 70mph. An automatic speed limiting system could also be put into place to limit speeds everywhere in real time. A low power emitter in every traffic signal in the nation could tell cars what the max speed limit might be and the software in the car keeps you from exceeding it. Done deal. If the issue is so serious let's just do that. I'd rather have cops devote their time to chasing bad guys than hiding behind a fence to give dumb traffic tickets to all the mommies taking their kids to school during the first week of class (happens almost every year here).

revelation 12y ago
Blood is running down the streets (just not literally). Traffic deaths are the top killer for kids under 15 in NYC; these aren't even people driving! They are killed by others, and often at speeds that are very, very likely to kill upon basically any collision. If you value science and data, you can tell from a mile what an enormously stupid idea it is to have multi-ton cars roaming cities at even 20mph. Physics tells us it's deadly, everything tells us people are incompetent and unfit to drive, and the statistics bear out the very, very high expected costs. I'd argue it can only be ignorance that would make you look at the tremendous body of evidence, both theorethically and statistically, and conclude > People are not suicidal. They'll drive at whatever speed is safe and comfortable for them.

lorddoig 12y ago

The standard of the average academic/research paper is low enough that very few stand on their own. This, of course, is the reason why certain media outlets are able to make lots of money with bi-weekly, likely untrue claims that <insert thing here> "causes cancer". This article repeats some conclusions from various research efforts of unknown (to me) quality, most of which carry caveats, and none of which were titled "Effects of Lane Width on Pedestrian Safety: A Quantitative View". These weak (not pejorative, just opposed to strong) statements are then used as the base assumptions atop which a logical argument is constructed - an argument that is incomplete. The relationship between speed and mortality is only attacked from the perspective of what happens once a collision has taken place, for instance, but there will likely also be a relationship between speed and the level of caution exercised by pedestrians, but no evidence about this is presented. This is a question in need of comprehensive study; the tidbits presented here are neither strong nor complete enough to say anything absolute, much less accuse anyone of having blood on their hands. Personally, I think such a study would validate much of what the author feels. But it is only my gut that says that, I'd need a study to "know". As such this comment is not meant as a criticism of the author or the thoughts in the article, but more as a sort-of defensive reminder of what the scientific method means.

andrewliebchen 12y ago
You wrote this from your car, didn't you?
kentonv 12y ago
Another thing missing: What is the economic cost of slowing everyone down? Clearly if people spend 50% longer commuting because they're driving 20mph instead of 30mph, that has real consequences for both their economic output and quality of life (commute time has a surprisingly large impact on a person's overall happiness!). The author disregards this factor entirely. I've seen this pattern in a number of "unintuitive and seemingly clever" traffic engineering tricks proposed in recent years. For example, it has been shown that removing all traffic signs can in fact improve safety -- again by slowing everyone down. Another similar point (mentioned in the article) is that expanding freeways doesn't reduce congestion, because the new lanes are filled quickly. The argument is, apparently, that we therefore should not bother expanding freeways. The argument ignores the fact that the expanded freeway is serving many more people, creating immense value even if the speed of traffic hasn't improved. (For the trolls: I personally take the train rather than drive whenever possible.)

AnthonyMouse 12y ago

> as state DOTs widen highways to reduce congestion, in complete ignorance of all the data proving that new lanes will be clogged by the new drivers that they invite. Let's see a cite to that data, because it seems ridiculous. Obviously if you make a road less congested people may start preferring it to other, more congested roads, but that just means the reduction in congestion is distributed rather than concentrated, and how is that a bad thing? The entire premise of this article is questionable. The theory is that people will drive more carefully when the roads are more dangerous. From this the argument is that we should make the roads more dangerous in order to make them safer. This is obviously completely counterintuitive so they point to some evidence that it could be true (which itself seems to imply that its veracity lies near the statistical margin of error). The real problem is that it's a false dichotomy. Making the roads more dangerous is not the only way to make people drive more carefully. And alternative ways of encouraging people to drive more carefully are obviously preferable to a method that, at a given speed and level of care, is more dangerous according to the laws of physics. More than that, this “make the roads dangerous to make them safe” is completely backwards when we're on the verge of commercially available self-driving cars. A self-driving car is obviously not bound by human psychology, so for all of those vehicles, making the roads more dangerous will only make the roads more dangerous.

joshfraser 12y ago
There's actually a ton of data to support the idea that making activities feel more dangerous makes them safer. I actually gave a talk on this topic a few years ago: http://www.onlineaspect.com/2010/07/05/ignite-boulder-11/ http://www.onlineaspect.com/2010/07/05/ignite-boulder-11/ How to Live Dangerously by Warwick Cairns is a great book on the topic as well.
- AnthonyMouse 12y ago
  > There's actually a ton of data to support the idea that making activities feel more dangerous makes them safer. I'm not disputing the idea that people might respond to perceived safety by taking more risks or vice versa. It's almost a corollary to the efficient market hypothesis. However, that doesn't tell you anything about whether they will overcompensate or undercompensate in any given context. And what I'm really objecting to is the idea that we should make people "feel" less safe by doing things that actually make them less safe if not for people [over]compensating for them. Because that's a very dangerous game if you're wrong and it's completely ignoring the possibility of solving the problem in other ways, which should on balance be more effective because you aren't running the wrong way with the ball.

chetanahuja 12y ago

I'm seeing a lot of resistance to the idea of narrower city streets on this thread. The advantages of narrower city streets (and hence, crossings) goes far beyond safety. It actually enhances quality of life in a significant way. A wide, four lane highway running across your town basically says humans must come encased inside an automobile. Pedestrians and cyclists become second class citizens. It's a design driven for the convenience of cars and to the detriment of humans. Here's a far more engaging critique of car-first design by James Kunstler: http://youtu.be/Q1ZeXnmDZMQ http://youtu.be/Q1ZeXnmDZMQ

cordite 12y ago
The university I went to invested in skywalks to replace many if almost all cross walks within and on the edges of campus. It does require more energy to go up and down sometimes, but it means everyone is safer and everything still flows.
- icebraining 12y ago
  How does it work for people with reduced mobility, wheelchairs, etc?
  - cordite 12y ago
    It is a spiral with an acceptable grading with rails.
- arthurdenture 12y ago
  The big problem with skywalks is that they result in the streets underneath them being empty (of pedestrians). This has downsides: - Empty streets feel less safe - Stores get less foot traffic - Cars are more likely to speed when there's no one walking about So they really can suck the life out of the street.
  - Dylan16807 12y ago
    Elevate the stores.

jff 12y ago

Ah, the old "If I don't wear a helmet, I'll ride more cautiously and never get into a wreck" argument.

megablast 12y ago
There is an argument that car drivers are more careful when they see cyclists not wearing helmets. And also the overall health benefits are better, when you consider that more people will ride without helmet rules. Only Australia has this requirement.
- jff 12y ago
  Crap, I was talking about motorcyclists, but didn't specify it in my post. This is literally an argument I have heard from other riders.

capcah 12y ago

I see a huge number of comments on this thread implying that carefulness is related to the road danger. It's the perceived danger that matters. You don't need to make the roads more dangerous, just need to make them look so. I'm not from USA, and on the last time I visited it, I noticed how recklessly people drive on the highways, most of them were on the phone, eating, or doing something else(there was even a lady fixing her hair with her right hand, talking on the cellphone with her left hand and holding the steering wheel with her elbow, that freaked me out). If those people behave the same driving on a street, I can see that being the cause of the majority of accidents, since the reaction time for events will be smaller, since most occurrences happen within a few meters of the car. Finally, I know that this is not the focus of the article, but the USA cities need to focus more on the people that either cannot or will not(like me) drive. LA, LV and Miami, for instance, were pretty hellish until I finally gave in and rented a car, with poor public transportation and pedestrian access.

click170 12y ago
I'm frequently surprised by the lack of sidewalks everywhere outside of the downtown core of many cities. Perhaps its different in cities I haven't been to, but compared to where I grew up in, it does seem like everywhere else is car-first. Its not just the states or even big cities, I've lived in a small town in Ontario that was similar. It makes me wonder if its related to the age of the area. Newer areas seem to have more sidewalks.
- marcus_holmes 12y ago
  I visited San Diego (I was living in the UK at the time, and found it impossible to get anywhere. I was routinely told that only poor people caught the bus (and it could be dangerous), and there were no pavements anywhere to walk on. I walked to the nearest burger place for lunch every day, a hellish 1-mile jaunt through rubbish-strewn wasteland getting beeped at every time I tried to cross a road. In contrast, every European and Australian city I've lived in has catered for pedestrians and cyclists to the extent that it's at least possible to walk or bike anywhere you need to go (even if it would take hours in these huge Aussie cities). I still wonder at it. How do Americans feel about living in such a shitty environment?

nashashmi 12y ago

This article completely misses the point of having wider lane path ways. Wider lanes help increase the speeds of vehicles and studies have shown that high speed traffic works far better than slow traffic. Just look up ramp metering where they deliberately keep too much traffic off of highways to maintain speed and maintain safety and maintain efficiency of roads. The cases where narrow street widths work better are places where there is more stop and go traffic like downtown areas where majority of the residences are crowded with store-front development. There instead of insisting on narrow lanes, you should insist on complete street designs that appropriately designs for all kinds of traffic. New urbanist movements seem to be behind this kind of lunacy of trying to create traffic conditions more difficult for cars. In New York, this trend has been set of by the Bloomberg administration and is labeled/marketed as traffic calming. It is really traffic impeding and is the center piece design of urban environments. I admit there are various benefits to it, but the underlying motivations are to be anti-gas guzzling vehicles.

nowarninglabel 12y ago
You should re-read the article. He specifically states he is no talking about highways, and further specifically states that throughput of traffic remains the same in areas with 10-ft lanes, and gives references to prove that.
ploxiln 12y ago
Your comment makes me think about this a bit differently. I live in NYC, and end up driving through it once every couple of months. While I'm normally sympathetic to people who hate anything that makes things easier for drivers and worse for pedestrians, if NYC is a model for "traffic calming", it's terrible, because I'm very angry and aggressive after 15 minutes of trying to drive in this place. I don't want to drive often, and I don't want to encourage more driving, but I want driving to be less difficult. Maybe make street parking 2-hour-max everywhere so there's room for cars and trucks to stop so they don't stop in the middle of the road, and they're forced to pay for off-road parking overnight, etc. Or something else, I don't know. That sounds severe, but the situation is already ridiculous.
- 12y ago

phkahler 12y ago

Even if I agree with most of that, I don't think keeping the road wide and using the outside area a bike lanes will work. People are going to see a wide road and drive fast anyway. I suspect you'd have to actually narrow the road, not just reallocate the concrete. But TD;DR maybe that was covered and I'm wrong.

raquo 12y ago
Anecdotally, in Vancouver we have narrow lanes in the city, with many streets having all kinds of bike lanes along their sides – both shared and separated. It works quite well, especially the separated ones. Narrow lanes surely do decrease average driving speed, it's damn uncomfortable to drive fast in traffic, and staying in the lane requires more concentration. I do miss wide Russian lanes sometimes, but the narrow ones are undeniably safer.
- mytochar 12y ago
  Separated bike lanes are absolutely wonderful. More of those and I would probably ride my bike more places.

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swartkrans 12y ago

This article makes me genuinely angry for burying the explanation for why 12 foot traffic lanes are dangerous beneath many paragraphs of what the author clearly thought must have been clever banter, wasting my time. Note to authors: put the claim and the gist at the top, then defend it with more details. Don't burry the gist of the article with shitty and annoying writing, making the reader scan paragraph after paragraph of bullshit to establish if the article is worth reading in the first place. In this case, it wasn't.

rando289 12y ago
Ya, and what about the people like me who gave up on that scanning and came here to find the tldr, but instead just found your complaint, and then read this complaint about the complaint!! When will it end?!
dalke 12y ago
Your anger should be directed to the person who linked to the site, and not to the author. The information you want is available at http://nacto.org/docs/usdg/lane_widths_on_safety_and_capacity_petritsch.pdf http://nacto.org/docs/usdg/lane_widths_on_safety_and_capacit... and in exactly the format that you want. Indeed, this is the source material for the article that you are angry about, as was cited in the text. The author wrote the article for people who want to read "shitty and annoying writing". There's enough of that writing in the world to know that those readers are in the majority. Those people also need convincing, don't they?

slashnull 12y ago

Please god of good urban planning give the force to Street Art the tagline "BUILD NARROW STREETS" everywhere

CodeWriter23 12y ago

About 8 or 9 months ago, they reduced the 3-lane thoroughfare through my part of town to 2-lanes with a bike lane, and narrowed the lanes to about 10 feet. People slowed down at first, but now people go just as fast as they used to, typically 5-10MPH over the speed limit, and some 15 MPH over (that's 50MPH). The radar signs installed as part of the project always read 40, 42, 45 and not just for my car. As a cyclist, the bike lanes don't really make me feel safer. There is a good margin of space between the bike lane and the car lane, but the bike lanes are really only in effect for half of any given block. The second half of the block, the line between the car/bike lanes is dotted, and cars can legally enter the bike lane, to make right turns. And then of course, anyone parallel parking on the street has to cross the bike lane to do so. Making the lanes narrower did not make pedestrian crossings any safer, as the road is actually the same width, and you still have to travel the same distance to cross the street. What did make it safer for pedestrians, the installation of flashing yellow warning lights at certain crosswalks, that pedestrians can turn on before crossing the street. Motorists see them and stop for people crossing, and that is a new and welcome effect. The bike lanes would have been much MUCH better implemented one block south of the main drag on a residential street that runs parallel. Much safer for cyclists. Healthier too, not having to breath as much vehicle exhaust. And probably a more optimal allocation of resources for the citizens. As much as everyone wants to be PC and become friendly advocates of human-powered transport, it really doesn't make sense in this part of town, to increase trip times and emissions for thousands of motorists daily, so the 50 people who choose to ride their bike can have a marginally safer lane to ride in. In Downtown L.A., it is completely different. Downtown, the bike lanes make sense because hundreds if not thousands of people use them. You always see a bike in the bike lane over there. But outside of the heart of the city, many people commute to work and carpool their kids to school and ballet and such. They're not going to ride bikes 5 hours a day to make that kind of commute. Oh, and where the traffic engineers failed to account for, and accommodate heavy traffic on a couple of heavily-traveled segments of the road, motorists now drive their cars illegally in the bike lanes during periods of congestion. IMO the project is mostly a failure. The safer pedestrian crossings are a great improvement. But the bike lanes such as they are, and the narrower lanes, just a waste of money. Putting the bike lanes on a side street would have been really great, a win-win for both cyclists and motorists.

12y ago

jchrisa 12y ago

This article just came out last night, suggesting that road diets are great bang for the buck when it comes to decreasing crashes. http://bikeportland.org/2014/10/10/less-500000-three-road-diets-preventing-37-crashes-every-year-112049 http://bikeportland.org/2014/10/10/less-500000-three-road-di...

CamperBob2 12y ago
At some point, people forget what the roads are for in the first place. You can also decrease crashes by enforcing a 5 MPH speed limit, right?

zenciadam 12y ago

If you're really interested in the subject and want to read more without dealing with the wanky blogger writing style check out "Traffic: Why We Drive the Way We Do" (http://www.amazon.com/Traffic-Drive-What-Says-About/dp/0307277194/ http://www.amazon.com/Traffic-Drive-What-Says-About/dp/03072...).

tdurden 12y ago

Seinfeld warned us of the danger of wide lanes quite a while ago : https://www.youtube.com/watch?v=CwinnODU0yo https://www.youtube.com/watch?v=CwinnODU0yo