Slowing Down to Move Ahead

The Woodrow Wilson Bridge project has begun an experiment to ease traffic flow through the construction zone around the Capital Beltway's Telegraph Road interchange. Our Commuter Page report on the "variable speed limit" system drew this letter.

Dear Dr. Gridlock:

The article on reducing speeds on the Beltway near the Wilson Bridge ("A Beltway Change Tomorrow," July 27) to improve traffic flow reminded me of an article I read in Scientific American in the late 1950s.

The study was on improving congested traffic flow in a New York-New Jersey tunnel by stopping traffic after every 20 vehicles had passed. It showed the empty road space buffered braking incidents, not allowing them to magnify into an avalanching line of braking. Vehicle flow increased, and delays decreased.

I have long tried to adjust my driving speed to anticipate traffic fluctuations ahead. This buffering minimizes brake and acceleration fluctuations for vehicles behind me. Fluctuations cause traffic flow oscillations, as well as increasing gasoline consumption.

The downside is that there are too many drivers whose personal time is more important than that of other drivers. Those people all too frequently speed up to cut into empty space between cars and then need to brake hard, disrupting traffic flow. If more drivers were not so aggressive and creating flow turbulence, we would have reduced commuter times.

Ronald Sheinson

Silver Spring