Making it up as they go along

New York City’s Central Park has a 25 MPH speed limit. Except it’s 15 MPH for bicycles. Except not anymore.

1991: New York City Central Park Commissioner establishes 15 MPH bicycle speed limit in Central Park based on “study” that involved people in cars driving alongside bicycles. I don’t know the specifics but it didn’t seem all that rigorous.

1993: Cyclists challenge discriminatory speed limit in court. Judge upholds the speed limit because of “police statistics that catalog the number of bicycle accidents.”

Last weekend: Police with radar guns ticket 10 cyclists for exceeding the 15 MPH speed limit. NYC Parks Department says, “15 MPH speed limit? Oh, we forgot about that and don’t care anymore” and removes the signs. Police revoke the tickets issued to nine of the cyclists.

More at the New York Times. See also Bike Snob NYC’s smarmy take on the topic.

Here in California, pedestrian and cyclist safety advocates sometimes grumble about this state’s 85th percentile requirement on speed limits and engineering requirements for any local government that would like to change it. This frustrates attempts to calm streets for a better pedestrian and cyclist experience on the road, but it also eliminates wacky arbitrary limits. I don’t know if that’s better or worse than a city parks department just making it up as they go along.

15 mph Panda


  1. Can you explain the 85th percentile thing?
    I’ve not heard of a bike speed limit in Illinois, but I believe the police still have the authority to cite a bicyclist going “faster than conditions safely allow” just like they could cite a driver who drives too fast in the rain or snow but still drives under the speed limit.

  2. The Basic Speed Law is sometimes applied to cyclists in California as well.

    85th Percentile — The state sets maximum speed limits for highways and residential streets and so forth. Lower speed limits are established at the 85th percentile (that is, one standard deviation above average) of drivers who drive on the road. Traffic engineers measure speed of traffic and set the speed limit at this 85th percentile level, which means we can have some high speed limits. It can be very difficult in California to establish a speed limit lower than this 85th percentile speed.

  3. So before an actual speed limit (not the maximum) is applied to a road, drivers are observed driving on the road and their speeds are recorded. Then the speed limit is set to the 85th percentile of observed speeds? So actual speed limits are higher than the average speed people drive? Hmm, weird.

    Portland is trying to get the authority from ODOT to set speed limits on their Neighborhood Greenways.

  4. Sort of. The prima facie speed limit for any local road is 25 MPH. You know drivers go much faster than that on a 60 foot right of way, and the speed limit must be adjusted upward to reflect the reality of how fast people actually drive.

  5. Wouldn’t the posting speed limit continue to rise as drivers are continually observed driving faster than the currently posted speed limit?

    The speed limit for all Chicago roads, unless otherwise posted is 30 MPH. I think that’s much too fast. The main bike drag, Milwaukee Avenue, is 25 MPH for many segments but I highly doubt people notice those signs.

  6. That 85th percentile rule is no problem at all. Take any freeway where people drive at 75mph. Install speed bumps that will rip out the suspension of any car travelling at 15mph. Measure the traffic speed. Voila, 85th percentile rule says the speed limit should be 15mph or maybe even less. The theory is that most people drive at a safe speed. Make the perceived safe speed on the road lower and people will drive slower. Change a speed limit sign and nothing else, and people will simply drive the same speed as before except when a police cruiser with a radar gun is in evidence (thus reducing temporarily the perceived safe speed). The grumblers have forgotten this, so I have little sympathy for them because arbitrary speed limits are a double-edged sword – as New York has demonstrated.

  7. Give the NYPD some credit for trying to enforce a law that actually existed some time ago, rather than one that’s entirely imaginary.

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