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Angie Schmitt writes in Streetsblog USA that city streets with the widest lanes — 12 feet or wider — are associated with greater crash rates and higher impact speeds and that there is hard evidence that wider lanes increase risk on city streets. Dewan Masud Karim conducted a wide-ranging review of existing research as well as an examination of crash databases in two cities, taking into consideration 190 randomly selected intersections in Tokyo and 70 in Toronto. Looking at the crash databases, Karim found that collision rates escalate as lane widths exceed about 10.5 feet. According to Karim "human behavior is impacted by the street environment, and narrower lanes in urban areas result in less aggressive driving and more ability to slow or stop a vehicle over a short distance to avoid collision. Designers of streets can utilize the “unused space” to provide an enhanced public realm, including cycling facilities and wider sidewalks, or to save money on the asphalt not used by motorists." Karim concluded that there is a sweet spot for lane widths on city streets, between about 10 and 10.5 feet.
According to Jeff Speck the fundamental error that underlies the practice of traffic engineering is an outright refusal to acknowledge that human behavior is impacted by its environment and it applies to safety planning, as traffic engineers, designing for the drunk who's texting at midnight, widen our city streets so that the things that drivers might hit are further away. "When lanes are built too wide, many bad things happen. In a sentence: pedestrians are forced to walk further across streets on which cars are moving too fast and bikes don't fit," writes Speck adding that a pedestrian hit by a car traveling 30 mph at the time of impact is between seven and nine times as likely to be killed as one hit by a car traveling 20 mph This tremendously sharp upward fatality curve means that, at urban motoring speeds, every single mile per hour counts. "Every urban 12-foot lane that is not narrowed to 10 feet represents a form of criminal negligence; every injury and death, perhaps avoidable, not avoided—by choice."
Original Submission
(Score: 2, Interesting) by Noble713 on Thursday June 04 2015, @05:12AM
Despite higher traffic volumes and population, Tokyo’s crash rates are 34% to 80% lower compared to Toronto’s.
I didn't read the article, but are they also taking into account things like the type of cars on the road? Tokyo's traffic includes a (compared to Toronto) much higher proportion of low-power kei cars (660cc displacement limit, typically about ~65hp). Not to mention a higher age of drivers. A bunch of old people driving glorified golf carts of course aren't going to be involved in as many high-speed collisions.
I wonder why modern megacities aren't developed with the vehicular traffic on the ground level and elevated pedestrian walkways at roughly the second-floor level. Just totally segregate the two types of traffic. The additional expense/maintenance would be worth it, dropping the pedestrian collisions to near-zero and increasing the flow of automotive traffic. Then we could remove a lot of the pedestrian-based automotive design restrictions and give us lower, lighter, sportier automobiles as well.
(Score: 2) by c0lo on Thursday June 04 2015, @05:47AM
Because your implicit assumption* about a "modern megacity" makes it impossible to find one.
*The implicit assumption is that such a "modern" city was developed "modern" from scratch and didn't evolve so from an older one, with its specific constraints and history that worth preserving and no extra (sometimes very high) cost of conversion and with no communities which "oppose such an abomination/eyesore/where are my trees" and whatnot.
A physically equivalent solution: sunk all the traffic in tunnels one level down under utilities - partially adopted by Paris, with its system of 4 ring roads having a significant part of them underground [wikipedia.org] - ain't cheap, that's for sure.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 1, Interesting) by Anonymous Coward on Thursday June 04 2015, @07:01AM
I would put the cars at least two feet into the ground instead. A car hitting whatever carries your walkways is likely to make them fall down, and cars driving through shop windows and even walls happen all the time.
Hitting a vertical wall of solid ground is going to stop most cars driving at reasonable city speeds.
But then my idea has the problem of how to cross the street, if yours is high enough, people can just cross above the cars.
(Score: 2) by deimtee on Thursday June 04 2015, @12:16PM
Interesting, but you would have the problem of the roads filling with water every time it rained.
If you cough while drinking cheap red wine it really cleans out your sinuses.
(Score: 2) by Immerman on Thursday June 04 2015, @03:01PM
You pretty much have that anyway - it's a rare rainstorm that puddles water deeper than the curb. Hence the network of storm drains to carry away the water. Permeable asphalt would also do much of the job, but that still hasn't really caught on even on normal streets and parking lots.
(Score: 2) by hemocyanin on Thursday June 04 2015, @07:05AM
I live just south of the US/Canada border. We get a lot of traffic from the Vancouver metropolitan area so I don't know if this is a (relatively) rural vs. city driving thing or just a Canadian thing, but Canadian drivers are often very bad: low use of signals, very poor metric to English conversion skills while hogging the left lane, and most of all, very aggressive tactics. There's also the issue with trunk-loads of gasoline -- not a good idea to rearend a random car from Canada on a Saturday.
Anyway, it could be the Vancouver area drivers specifically -- or it could be common throughout Canada ... or it could just be a rural vs. mega-city difference in driving styles that I mentioned before. No matter what it is, I think it would have made much more sense to compare different Canadian cities (or Japanese ones) -- or different roads in the same city. Even in the US, east coast drivers are way more nasty than west coast drivers on average, so comparing some little town in Oregon for example, to a similarly sized town in Massachusetts is not all that valid. Last, so as not to piss off only the Canadians around here, I remember this joke from my time in Vermont: what do you call a Massachusetts driver? Masshole.
Signed,
Mr. Magoo ... (of whom I'm aware solely because of the CBC)
(Score: 0) by Anonymous Coward on Thursday June 04 2015, @07:43AM
And no I-talians. so that has to count for something. A small percentage of Japanese drivers are "baka jidosha". Or following that movie that is up to number six, with dead guys in it.