Wiki Wednesday: Twenty’s Plenty

Excellent StreetsWiki use by Streetsblog regular ddartley, who added the pic you see below to the entry on 20 mph zones. From author Andy Hamilton:


In July 2008, the British Medical Association called for the
application of 20 mph zones throughout residential neighborhoods, not
just in the vicinity of schools, where they are commonly applied.
Stockport public health director Dr. Stephen Watkins stated that "a
child hit at 20mph has a 5% chance of dying compared to 50% at 30mph."
He noted the difference between a two mile journey at 20mph and a two
mile journey at 40 mph was just three minutes. "We are killing our
children for the sake of a couple of minutes," he said.

And since we’re in stimulus mode, here’s another excerpt:

The UK study of best traffic practices across the Europe and the U.K.
concluded that 20 mph streets also increased pedestrian activity,
bicycling, a sense of safety among residents, and economic activity. 
The study cited evidence from the city of Horsham, U.K., where 20 mph
speed limits, along with a bypass road, public arts, gardens, and other
pedestrian amenities have lead to the opening of new shops and
restaurants, and a higher level of overall economic activity.

Okay, I’m convinced. Let’s get some shovels in the ground on those ped safety plans.

  • Omri

    I think you mean kmh, not mph.

    Britain is metric.

  • James

    Not only that, but speed limits aren’t the issue within the 5 boroughs of NYC. The speed limit is a universal 30mph on all city streets except parkways and highways, yet because the NYPD does not enforce, the law of the jungle prevails. If the NYPD did it’s f****** job and enforced the laws on the books, the issue would take care of itself. The city could make an absolute killing on traffic tickets if someone had the balls to take this issue head-on.

  • Since when is Britain metric? If you’d just bothered to look at the linked Streetswiki entry you’d see that the UK links all say “20mph,” as does the 20’s Plenty web page.

  • Hi! I completely agree. these streets are very unfriendly. there are times, we need to use vans instead of our moving trucks to get to our destination and it usually cost our clients’ money even if we don’t want to. we are left with no choice. I hope they make street that are friendlier to pedestrians and automobiles both. thanks! =)

  • Omri

    Mea culpa.

  • But 20 mph is much, much better for pedestrians, as those fatality figures indicate. Enforcement is absolutely necessary, but the lower speed will make a huge difference.

  • One of the most substantial changes that’s been made on Skillman Avenue in the past year was to retime the traffic signals so that if drivers go more than 20 MPH they hit a red light. That has made a big difference in the feeling of safety on the street. More needs to be done, but if the whole city were at 20 MPH (excluding expressways and parkways), it would be easier to get more streets retimed for these speeds.

  • ddartley

    James, you have a point about enforcement but I disagree that the speed limit isn’t an issue.

    Even if enforcement kept all NYC traffic to 30mph or slower, there are numerous ways 30 mph is still a dangerous and inappropriately high speed for an environment like NYC. And even if we know that cops won’t reliably enforce the speed limit, that by itself is not a reason not to officially reduce it.

    I used to talk about officially reducing NYC’s default speed limit as if that by itself were a panacea. Now I know there’s much more that can to be done in addition (or, if necessary, instead–such as the signal timing changes on Skillman Ave), but I still that particular change as absolutely essential to many aspects of NYC’s livability.

    One Angus, I haven’t been to Skillman Ave in a while but I would bet you’re right that the whole place feels considerably safer because of the change, and if I understand correctly, you helped effect that change yourself. Kudos.

    Thanks Ben for the kind mention in the article. My wife was very patient with me on that trip as I constantly stopped to photograph Scotland’s–not hills or castles, but traffic control devices.

  • ddartley

    “One Angus?” Clearly I believe in making little revisions before posting, but not in doing a final proofread.

  • If asked to make the default speed limit in NYC 20 mph, the city would likely say it would be impossible to enforce. Well, the city is not enforcing the 30 mph.

    Even if enforcement is lax, 20 mph would still do a lot of good. it would outrage a lot of motorists, and in so doing, raise a lot of awareness about why it makes sense. it would also make it much easier for the DOT to re-time signals for slower signal progressions (as noted above), and install more speed humps and other traffic calming devices. even if only 10% of motorists followed the new law, these drivers would serve as mobile traffic calming units.

    the department of health should take this on. name another public policy that would, virtually overnight, save as many lives and injuries and stoke walking and bicycling.

    and in the future, automated speed enforcement cameras would be a great way to improve enforcement of a 20 mph limit.

  • J

    Someone should start a petition to the department of health. I’m sure we could get a bunch of CBs on board. Plus we could get medical experts from around the country to testify to the benefits of this. The dailies would certainly pick it up and if the job is done well, we could spin it as an obvious safety measure. TA? You got 100,000 signatures for a car-free park. This sounds right up your alley.

  • Paul Steely White, any chance of it getting formally onto the agenda of your excellent organization? I’m overdue in offering volunteer services to it (i.e. never have, other than membership fees + year end gifts), but to help lobby NYC to reduce the default internal speed limit, I might just become an envelope-stuffer extraordinaire.

  • The bad news is that the real speed limit in the city is the maximum allowed by our street design.

    The good news is that we can reduce speeds by changing street design — for instance, using speed bumps.

    The even better news is that the speed limit imposed by street redesign is automatically enforced by the street itself. It requires no intervention by the NYPD or anyone else.

    The bad news (back to that again) is that financial and energy constraints will make street redesign less likely to happen in the future — you need diesel-powered equipment to install speed bumps. So we must act now.

  • Ddartley: i like your enthusiasm. can you all drop by the T.A. office Tuesday around 5:30? we could talk about this as an initiative… or just email me offline and we can set up a time.

  • Larry Littlefield

    I’ve got family who live in Tulsa OK, where they moved as a result of being unemployed in NY during the deep 1970s recession. In fact, I spent my last two years of high school there before returning.

    In Tulsa, and many western cities, you have major streets every mile, creating a set of mile squares, with local neighborhoods within the squares.

    In the local neighborhoods, the speed limit is 25 miles per hour, except near schools, where it is lower.

    On the major streets, which tend to have two lanes in each direction, it is 35 to 45 mph, with most streets at 40.

    If Tulsa, with few pedestrians, can have 25 mph, why not 20 mph in NYC for narrow streets — those with three or fewer moving lanes total?

    The speed limit, however, is UNDER THE CONTROL OF THE STATE OF NEW YORK. So forget it.

  • I’m not crazy about speed bumps; people just speed up in between them. There’s got to be a better way.

    Metrication in the UK has been as contentious as it would be here, as far as I’m aware; they especially aren’t enthusiastic about beer in half liters rather than in pints.

  • I shall be there!

    To pick up on what Mark Walker said, regarding physical changes to control speed vs. speed limits: it occurred to me that physical changes could of course have the separate effect of slowing down emergency vehicles as well as mere jerks (several other cans of worms, I know), which was a discouraging thought because I’ve always liked the idea of physical changes to control speed.

    But bridging the two methods of controlling speed, of course, are things like what Angus talked about: re-timing traffic lights. All such methods–cheap or expensive–deserve more of the City’s attention.

  • Larry, 10 years ago T.A. fought for and got passed a state law that gives the city the authority to set speed limits as low as 15 mph, with some conditions. this law could be invoked, tweaked, or both. in any case, i agree that the first step is making this a public health imperative.

  • Larry, (I suppose I could look this up rather than post an uninformed blog comment, but…) in an informal conversation I had once with a Council Member’s staffer, he said he thought NYC does have authority over its own streets’ speed limits, just not the highways.

  • Larry Littlefield

    (Larry, 10 years ago T.A. fought for and got passed a state law that gives the city the authority to set speed limits as low as 15 mph.)

    I did not know that. Wow! What a huge change that is, and what a great victory for TA, given our experience with the state.

  • Doug

    I find a programmable GPS to be a reasonably effective device to reduce speeding. First, you’ll find that driving fast scarcely reduces the arrival time, so why bother? Second, you’ll know the effect of congestion as you sit in traffic and watch your arrival time increase, somewhat like watching a taxi meter.

    There will never be serious traffic enforcement in NYC until we put in widespread speed cameras, similar to most other countries. My daughter lives in Australia, and she mentioned that reckless speeding quickly fills your mailbox with expensive speeding tickets. The city could use the money, and we could all use a respite from speeding cars, trucks and taxis. Why not use them?

  • This is an important wiki entry (and an urban-appropriate speed limit will be a key item in my 2009 version of the idealized vision plan for transportation in DC) but it is seriously deficient by being UK centric and not discussing Graz, Austria, where the 30/50 kph speed limits were first initiated, in 1992. I am not an expert on it, and have been looking for a good paper on the topic, which I have not yet found, but this entry is deficient without that info. Plus, it provides a great example for effectiveness and the ability to enact it, as it has been in force for 17 years.

    Great photos@ (which I will use in my entry)

  • Max Rockatansky

    Traffic cameras are a great idea but I believe that has to be approved by the state and they’re not playing along due to privacy concerns.


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