Archive for June 22nd, 2009

And speaking of urban speeds:

“A speed of twenty miles an hour within the city is dangerous, the speed of thirty miles an hour permitted by the Callan law is reckless and should be made dangerous.”

From the New York Times, 1912.

Car stopping distance has improved since then, whether human reaction times have is another question (particularly when they are in-texticated or otherwise impaired); the non-linear upward graph of car speed and risk of pedestrian death certainly hasn’t changed (and may have gotten worse with heaver vehicles with different profiles).

What has also obviously changed is the language — the quote in the title comes from the same article — which itself reflects the cultural accommodation of the city and culture to the car (and, as historian Peter Norton has shown, a gradual shifting in the balance of responsibility for safety onto the pedestrian).

(thanks Beany)

Speed limit signs tell the driver how fast they can legally drive. What if they actually told them something more useful — namely how fast to drive so that one is assured of not having to stop at the next light?

The following press release came to me recently:

Information Display Company, a leading developer and manufacturer of radar speed sign technology today announced the launch of TrafficFlow Manager, a driver alert display that works with traffic signal timing to alleviate traffic congestion. When mounted along a route with timed traffic signals, the display informs drivers that the lights are synchronized and lets them know the proper speed they must maintain in order to avoid having to stop for a red light.

The benefits of light synchronization are obvious; for example:

A report issued by the U.S. Department of Transportation showed that a traffic light synchronization program in Texas reduced delays by 24.6 percent and fuel consumption by 14.2 percent. A similar program in Austin Texas saved commuters 2.3 million hours of their time and 1.2 million gallons of fuel usage.

There are obvious limitations — for one, the systems are more expensive than conventional lights (and not sure where that money is coming from in current municipal budgets); for another, when competing traffic demand is high, synchronization schemes often break down.

Another question is whether an unbroken string of green, in urban areas for example, encourages speeding. Which is why I was intrigued by the idea of this “functional” speed limit sign. As I’ve said before, I’m constantly amazed by the inefficiency of drivers in New York, accelerating from red light to red light, often beyond the speed limit itself. But the question begs: If, upon getting a green, if drivers knew that driving 28 mph would get them to the next light when it was going to change, and that to go faster would simply cause them to have to come to another stop, would they actually drive at that speed?

This strikes me as in the spirit of a Nudge — there’s nothing (except that pesky old law) standing in your way of making any speed choice you like, but you are given clear information on what the best choice is. Still, questions loom — what if someone joins the street from a side-street, and has no idea of where they are in the synchronization scheme, and may drive faster for fear of the light turning red.