Everybody out of the pool: unpopular carpool rules are finally running out of gas.

Back in 1990, the federal government picked up Reg. XV, a Southern California ridesharing regulation, and enshrined it in the federal Clean Air Act. The rule forced large employers in highly polluted areas to adopt programs that would induce their employees to "rideshare" using carpools or other alternatives to driving alone. Rideshare boosters promised not just cleaner air but less stress, lower costs, and increased camaraderie among commuters. Rideshare fairs and carpool posters sprang up like weeds as other polluted regions adopted clones of Reg. XV.

But ridesharing didn't work. Employees didn't want to abandon the flexibility and autonomy of driving alone. Employers had to offer a lot of costly incentives to get tiny increases in carpooling, producing tiny air pollution reductions at ridiculously high costs. Zealous air pollution bureaucrats created a morass of rules and regulations that dictated everything from the educational level of "employee transportation coordinators" to the rank of the company officer signing the company's pledge to support ridesharing.

One Southern California aerospace company spent more than $1 million a year to promote ridesharing and had to submit 23 separate plans detailing how this was to be done. One year, it was told to repaint all of its 45,000 parking spaces so it could assign "preferential parking" based on how often commuters shared rides. Regulators backed down only after the company demonstrated that union rules would result in a cost of $100 per space repainted - that's right, a total of $4.5 million - to assign preferential parking to less than 10 percent of the employee population.

Retreating in the face of a constant barrage of criticism and horror stories, Southern California has progressively weakened its ridesharing rules, and state legislation passed in late 1995 requires air pollution agencies to make rideshare rules voluntary. (Though at press time, the replacement offered in Southern California seems likely to be more costly than the rule it is replacing.) But the battle has been slow, both in California and in other rideshare-mandate states, with rideshare boosters pointing to the federal Clean Air Act as the ultimate justification for preserving regulations at state and regional levels.

Now that has changed. In December, President Clinton signed Illinois Rep. Don Manzullo's H.R. 325 into law, modifying the language in the Clean Air Act to specify that employer rideshare programs are strictly voluntary and at the discretion of state and local agencies. Prospects are good for the eventual withering away of mandatory employer rideshare rules, now that the support of the Clean Air Act has been removed.