Their Number Is Up : Traffic: Motorists in Thousand Oaks slow down when they see their speeds announced ahead in huge yellow figures.

Hundreds of cars zooming down Thousand Oaks Boulevard zoomed a little more slowly Thursday as police unveiled a new radar trailer that confronted speeders with their crimes in foot-high yellow numbers.

The $8,000 solar-powered trailer, one of two that will be placed throughout the city of Thousand Oaks, drew mixed opinions from passing motorists, but a uniform reaction: They dropped their speed.

“They’re slowing down. They’re backing way off,” said Lt. Mike Brown, watching the radar trailer’s digital readout plummet from 48 m.p.h. to 38 m.p.h. as drivers realized what the roadside contraption was.

Even if drivers reduced their speed, they were not necessarily happy about it.

“I don’t like it. That’s why I carry a Fuzzbuster,” said one driver stopped at a nearby red light, proudly pointing to the radar detector on his dashboard before blasting away in his jet-black luxury car.

Still others said they would like to see the trailers moved to their own residential neighborhoods.

“They don’t want people speeding down their streets when kids are playing,” said Cmdr. Kathryn Kemp, explaining the sentiments that have led residents to request special speed patrols at more than a dozen locations in Thousand Oaks.

The three traffic officers usually on duty are hard-pressed to monitor speeding traffic, as well as handle crashes, officials said. The trailers, which can be moved about and then left unattended, will make it easier for the department to fulfill demands for service, police said.

At the trailer’s debut Thursday afternoon, cars sped by going as fast as 59 m.p.h. The speed limit on Thousand Oaks Boulevard is 35 m.p.h.

Unlike some more expensive radar trailers recently installed elsewhere in California, the Thousand Oaks devices do not carry video cameras and do not automatically issue tickets to speeders. In fact, most of the speeders who passed by Thursday on Thousand Oaks Boulevard escaped scot-free.

But they will not always be so lucky. “Just because this is here doesn’t mean there isn’t a traffic officer down the road another block and a half,” Brown said, warning that officers will periodically be stationed near the trailers to write tickets to the worst offenders.

Even without getting tickets, drivers confronted with the trailers will slow down and become more conscious of their driving habits, police said. The readouts can also help motorists calibrate their speedometers, police said.

Similar trailers came to Camarillo in 1990 and will soon be operating along roadsides in Moorpark, authorities said.

Despite what they called “horror stories” about drivers speeding up as fast as possible as they approach unstaffed radar trailers, police said they believe most will slow down.

“There are always going to be a few that don’t care, but the vast majority will take heed,” Brown said.