May 22, 2014

Annals of Walking – 27: Thirty kph for Paris …. Are countdown signals safe?

A pedestrian perspective.



Révolution à la française


From World Streets:

The just-elected new Mayor of Paris, Mrs. Anne Hidalgo, has prepared a revolutionary sustainable mobility project whereby virtually all of the streets of the city will be subject to a maximum speed limit of 30 km/hr.

The only exceptions in the plan are a relatively small number of major axes into the city and along the two banks of the Seine, where the speed limit will be 50 km/hr, and the ring road (“Périphérique”) where the top permissible speed has been reduced from 80 to 70 km/hr.   On the other end of the equation are a certain number of “meeting zones” spotted around the city in which pedestrians and cyclists have priority but mix with cars which are limited to a top speed of 20 km/hr. A veritable révolution à la française.

More here.


The above piece got big reaction:

A great many people apparently, to judge by the reaction to our yesterday’s World Street posting on the decision of the city of Paris to limit virtually all traffic in the city to a top speed of 30 km/hr. That article literally blew the lid off of the normal reader reaction to postings here, which commonly run in the hundreds at most in the several days immediately following publication. In this case we were deluged by more than 4000 readers who checked in from more than 50 countries.

More here.




Are countdown signals safe?

pedA new study suggests not: The impact of pedestrian countdown signals on pedestrian-motor vehicle collisions.

This study examined the frequency of PMVC (ped motor-vehicle collisions) before and after installation of PCS in the City of Toronto over a 10-year period. The main objective was to determine whether PCSs were associated with any change in PMVCs, controlling for seasonal and temporal effects.

The potential for benefit exists if pedestrians use the PCS timer displays to make safer road crossing decisions. Conversely, the potential for harm exists if PCSs cause pedestrians to rush or drivers to accelerate in response to the timer display. Either possibility may enhance the likelihood of a collision.

The results:

This analysis demonstrated an increase in PMVC rates of 26% at intersections, post-PCS installation. The increase in PMVC rate was more pronounced in adults, and for severe and fatal collisions. These results controlled for baseline PMVC rate, season, as well as installation year.



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  1. Interesting to note, in the city of Copenhagen, most of the pedestrian signals go from green to red without a flashing phase. I have no ideawhat their collision rates are as a result but their overall traffic safety track record is better than ours.

    1. I admit I’m skeptical of the findings, though to be fair I haven’t dug into the research deep enough to understand.

      Anecdotally, as a pedestrian I like the countdown timers because I know how long I have before the light changes. That is, it gives me information I can use as a pedestrian to decide whether I have enough time to cross the road before the light changes.

      As a motorist, I also like the countdown timer because I know when the light will change from green to amber. Even before the countdown timer I used the pedestrian signals (walking man, flashing hand, solid hand) to try to determine this as well. At intersections that do not have the timer I have to make a decision before I reach the intersection as to whether I have crossed a “line of no return” where if the light changes from green to amber it is no longer safe for me to attempt to stop. Also I’m more or less staring at the light as to not miss the change should it happen.

      With the countdown timer I can make this decision 10 or more seconds earlier and am not surprised that the light changes. I can maintain my speed and therefore do not need to dangerously speed up or slam on my brakes.

    2. I’m with Octavio. I like the countdown timers as both a pedestrian and motorist. More information provided earlier should improve outcomes for everyone. That additional information encourages some to take additional risks is truly unfortunate.

      There’s a street near me where the signal timing hasn’t changed in decades. When I come around the corner and see the signal 6 blocks away I already have a pretty good idea whether or not I’m going to have to stop. If it turned red just before it came into view I won’t know with absolute certainty until I’m halfway there, but most of the time I’ll know 4-5 blocks away whether I’ll be using my brakes or not. Some times I deliberately drive under the speed limit so my arrival at the intersection will occur shortly after the signal turns green. Saving gas and brake wear is a good thing. Driving slowly also reduces the chance of collision with an animal, pedestrian or other vehicle that might suddenly and unexpectedly cross my path.

      I can only predict the future when approaching one intersection from one direction. A computer controlled car hooked into the signal system would always be able to plot an optimal course with a minimum number of stops.

  2. Here is my highly scientific take on this: (1) TMI. (2) makes some of us feel like a dog in a laboratory. (3) big brother is not far away. (4) I observe that they seem to make people stressed and in the process self-centered and antisocial – me, me, me . (5) They are ugly.

    Now I await docilely to be put firmly in my place.