Monday, November 27, 2006

Mental gridlock

Steve's recent post about no-rules traffic reminded me of interesting, and sometimes surprising, ideas about traffic.

For example, near Steve's house is a wide two lane street that is a dangerous for pedestrians to cross because traffic is moving fast (for a residential area) and the road is so wide that pedestrians spend a long time crossing. It is a road in need of traffic calming. One technique is to reduce the radius of sidewalk curves at intersections (reducing road width -> pedestrians are in the roadway less time).

It is a little counter intuitive, but congested narrow residential streets might be safer for pedestrians. I seem to remember a few years ago a consultant recommended to the City of Reedley not to indulge the instinct to install stop signs willy-nilly, and making wide residential road. Unfortunately, Reedley is now The Land of Many Stop Signs.

Another interesting thing is that the modern traffic roundabouts are more efficient and safer than intersections controlled by stop signs or signals.

There's also provocative data about urban vs. rural traffic fatalities. Somewhere (Tufte?) I saw a map of the US showing by county the traffic fatality rate. That map is essentially the mirror image of a map showing population density by county. I can't find the map on the Web, but the "Partners for Rural Traffic Safety" say

More than half of fatal crashes occur in rural areas: 59 percent of total traffic fatalities for all vehicles and 64 percent for passenger vehicles.

The fatality rate in rural areas is TWICE that of urban areas: 2.6 deaths per 100 million vehicle miles traveled versus 1.1 in urban areas.

Restraint use in rural fatal crashes is LOWER than in urban crashes: 36 percent versus 48 percent.

Finally, the "safer to drive or fly?" question pops up in the Risk Digest:
As for the cliche that the drive to the airport is riskier than
the flight, the researchers concluded that average drivers with
the age distribution of airline passengers are less likely to be
killed on a 50-mile, one-way trip to the airport than on the flight.

Speaking of flying, a new record was set today for amount of time before I get panhandled in San Francisco. This record is likely not to be broken since as I was getting out of the airport-hotel van, I was asked for money immediately.

One more thing, according to the June 2005 Harper's Index:

Portion of the world's motor vehicles that are in China: 1/17

Portion of the world's annual traffic fatalities that are: 1/5