The Slow, Idle Drift Toward Disaster : Cars are killers at slow speeds, too. What’s the remedy?

During the morning rush, most fumes drift toward the sun and become smog. But when commuters choke a Southern California freeway with cars at evening rush hour, the freeway chokes back. It may seem to commuters that they breathe in every stinking bit of what the tailpipes around them pump out.

Consider the difference between the pollution from a car that is free to cruise at the speed limit and one that is not. It is estimated that if it takes you 30 minutes to cover 10 miles in slow, heavy traffic, your car pours out 250% more hydrocarbons than one that covers the same distance in 11 minutes. An idling engine pours 300 times as much carbon monoxide into the air as one that is running free. For Californians with heart problems, carbon monoxide can be deadly--and surely it’s no big help even for people with the healthiest hearts.

Enter Proposition 111 and the $18.5 billion it would provide from higher gasoline taxes to build and improve roads, expand commuter rail systems and jump-start a variety of programs to improve California transportation. The money will not make either the smog or the congestion disappear. But without it, smog and congestion could stifle the state’s future.

Technology that traps pollution before it can get out of the tailpipe is so much better than it was 20 years ago that cars burn 80% cleaner. But sheer growth in the numbers of cars and in the miles they are driven is likely to cancel out the gains of technology in 10 years and put pollution once more on the rise.

About $3 billion of the Proposition 111 money will go to local governments to help them plan and pay for congestion-busting programs--expanded ride-sharing, new transit service and, among others, the creation of “smart streets.� Cutting congestion on surface streets is crucial because they carry more than half of all trips in and around cities.

Making a street smart starts with selection of broad avenues such as Pico Boulevard in Los Angeles or Beach Boulevard in Orange County and coordinating traffic lights so that a car has a good chance of catching all green lights at a posted speed. Such streets will be wired so that sensors can report traffic flow to a control center that could change signal timing automatically if necessary. In the final phase, a computerized switchboard will give any caller a traffic report for a street by name. The goal is breaking up traffic jams; the bonus would be fewer stops at red lights and fewer idling engines.

Smart streets alone will not banish the smog that exceeds federal health standards nine summer days out of 10, but they will help. So will more ride-sharing: The state’s own Clean Air Act of 1988 requires raising the average of 1.1 persons per car during rush hour to an average of 1.5 by the end of the 1990s. So will dozens of other technical fixes in combination with changes in old habits that make Californians think first of sliding behind a steering wheel when they need to go places.

The pressure for change and careful planning of a transportation system for the next century is intense.

Proposition 111 will not ease the pressure, but it will help Californians deal with it.