The streets are slick with rain, it's twilight, still drizzling, and all of a sudden a pedestrian appears out of nowhere and steps in front of your car.

It happened to Mike Harrison's friend on a gray Santa Rosa evening around Christmas 1991. The person crossing the street did not survive, and it took Harrison's friend years to overcome the emotional toll of accidentally killing someone. The tragedy spurred Harrison, a former commercial pilot and full-time inventor working from the bedroom of his Santa Rosa house, to build a crosswalk warning system. After years of testing, orders are now pouring in for the system from across the country. It works like an airport landing strip, with flashing lights embedded in the street on both sides of a crosswalk. When pedestrians step into the walkway, a row of blinking amber lights is automatically tripped, giving motorists a heads-up to step on the brakes.

Each year, about 6,000 pedestrians nationally are killed by drivers -- the equivalent of a commercial jet crashing with no survivors every two weeks, according to the Washington, D.C.-based Surface Transportation Policy Project. In the Bay Area, 115 pedestrians were killed and more than 3,700 pedestrians injured in 1996 alone, the group found. Transportation planners around the country say Harrison's invention could help lower those numbers.

Right now, the system is being used in Lafayette, Orinda, Petaluma and Santa Rosa, with another one being installed soon on Port of San Francisco land near Pier 52. San Francisco planners wanted to install five others, but it was lined out of the most recent city budget. The devices are also on streets in Florida, Nevada and Washington, with orders coming in from Hawaii to New York. And Saipan in the Mariana Islands has six systems, all solar-powered. But even without solar panels, the units require little energy to operate -- about as much a 20-watt lightbulb. They are priced at around $20,000, compared to as much as $150,000 for a traffic signal. The lighting system really shows up at night, when statistics show that pedestrians are 1,100 times more likely to be hit by a car than during the day.

The challenge for Harrison and his company, LightGuard Systems of Santa Rosa, was to make sure the lights were the right hue of amber, designed so that they flickered in any direction yet did not pulse at rates that might induce epileptic drivers to have seizures. After years of testing and tinkering with the lights, the firm seems to have hit the mark. Motorists say the strobe-like flash catches their eye without dangerously distracting them. ``You can't miss it, especially at night,'' said Kathleen Rosano of Santa Rosa. ``It really makes you slow down. I think these things should be everywhere, in every city.''

The idea was born in Santa Rosa after seven people were killed on city streets in 1991, including the accident in which Harrison's friend was involved. After the wave of fatalities, the police chief asked the community for help in coming up with ideas to prevent more accidents. That is when Harrison, who made his living piloting home builders around California in a twin-engine turboprop plane, parked the aircraft and picked up a screwdriver. ``At first, I thought it probably had already been thought of before or that it wouldn't work to embed lights in the pavement,'' said Sal Rosano, Santa Rosa's police chief for 22 years before he went to work for the National Highway Traffic Safety Administration. ``But now I am convinced this saves lives,'' he said. ``I think it's the wave of the future for pedestrian safety.''

Other people, however, are not as sold on the system.

The California Department of Transportation has not yet given the design its stamp of approval. In order for California cities to get the federal government or the state to pick up the tab for the system, Caltrans must classify the devices as ``standard'' pedestrian equipment -- something that is still being evaluated. And some high school students hanging out at Putnam Plaza in Petaluma, where the warning lights are installed on Petaluma Boulevard South, gave the system a thumbs down. The students appeared to take the system for granted -- and, in their opinion, the flashing lights do not get drivers to take notice. ``It's useless,'' said Natt Townsend, a sophomore at St. Vincent's School for Boys in San Rafael. ``They're a big waste of money.''

But the lights do appear to be slowing drivers in downtown Petaluma and other Bay Area cities. In Petaluma, for example, the percentage of motorists who yielded to pedestrians at night shot up from 52 percent before the system was installed to 80 percent afterward, according to a study conducted by Stephen Weinberger of W-Trans, an independent Santa Rosa traffic consulting firm.

Averaging all the cities using the lights, 70 percent of drivers yielded to pedestrians at night compared to 17 percent before the system was installed, according to the study.

Not bad for a lighting idea that burned only dimly in the early years when Harrison and his brother, Brian, were a two-man team wearing hard hats and pounding lights into a Santa Rosa street. Now, five years later, there is a 2,500-square-foot assembly plant in Healdsburg, investors, a pending patent and a fully staffed Santa Rosa office with a U.S. map on the wall littered with yellow-flagged stickpins pointing to orders around the country.