Laser Radar Guns Zero In on Individual Speeders

Beneath a stand of pine trees along Sherman Way in Van Nuys, Los Angeles Police Traffic Officer Troy Williams waits with a hunter’s disposition as his prey heads straight into his gun sight.

A GMC Safari has surged from a pack of cars and is closing fast from a distance of several hundred feet. Williams pulls the trigger, which emits a high-pitched wail before a flash on his digital display reads 61 mph--in a 35 mph zone.

If you are among those who like to push the pedal to the metal but dread the feeling that comes with a speeding ticket, traffic school fees, higher insurance premiums and associated court costs, meet your new enemy: laser radar or “lidar.”

Unlike radar, which casts a microwave signal over a broad area of the street, lidar guns allow officers to take direct aim at a car in individual lanes, from hundreds, even thousands of feet away.

Most police agencies currently rely on “K-band” microwave radar, which allows traffic officers to nab the fastest car on the road whether they are on the move or concealed by the side of the road.

Although radar is still the technology of choice, its big shortcoming is its inability to pinpoint individual cars from far away, police say. For each 100 feet an officer is removed from his or her target, the width of the microwave beam grows by 21 feet.

Not with lidar. Even from 1,000 feet away, a traffic cop can lock on a target in which the beam is no wider than 3-by-3 feet--equivalent to picking a spot on a car’s trunk or front grille area.

“The officer can take the laser beam and put it on a vehicle whether it’s coming or going and give you a reading,” said Sgt. Dale Turner of the Los Angeles Police Department’s Valley Traffic Division. “In short, it makes them better enforcers.”

Lidar’s precision also gives police the ability to take speed readings on several vehicles as they approach. On a recent winter day, Williams was able to get readings on five vehicles within 800 feet.

The longer lead times allow officers to flag cars down without having to chase after them, although Williams’ pursuit of the GMC Safari traveling 61 mph took him across traffic lanes and down Sherman Way for more than a quarter-mile.

The technology can help law enforcement in other ways, according to police and sheriff’s deputies. Although judges uphold about 97% of all speeding tickets, pinpointing specific vehicles effectively counters traffic court defenses, such as “the officer got the wrong car” or “the driver next to me was speeding,” police say.

LAPD Valley Traffic Division Capt. Greg Meyer said it also makes racial arguments moot. “From a thousand feet, it’s hard to judge the make of a car, much less the race of its driver.”

Besides nabbing speeders, traffic officers say, the devices have proved valuable at accident scenes, providing precise measurements of skid marks, showing a vehicle’s position on the street and marking debris fields and areas of impact.

Lidar has its limits, however. It does not work mounted on a moving squad car or motorcycle, which is one of the reasons the California Highway Patrol has only a handful of the devices, according to CHP officials.

Nor can it provide accurate readings in foul weather or, in some cases, when aimed at a dark-colored car with a sloped front.

Lidar also requires a clean field of vision between gun and target, which means that in many urban areas, officers must get closer to the open street to use it.

Los Angeles Sheriff’s Det. Glenn Callaway, who trains officers in the use of lidar, says it gives drivers the benefit of the doubt because the angle of the beam can produce readings at or below a vehicle’s actual speed.

From a 10-degree angle off the road, the officer’s reading is one mile an hour lower than the motorist’s at speeds of about 55 mph. If the beam is fired at a 20-degree angle, the total would drop by 4 mph.

With any speed detection technology, Callaway said, officers must first come up with a visual speed estimation. If the speed detection device backs up the officer’s observation, he issues a ticket.

The LAPD and the Los Angeles Sheriff’s Department have been slowly accumulating the devices. At $3,500 per unit, lidar remains prohibitively expensive for departments to deploy many of the devices.

The sheriff’s stock of lidar guns has grown to 75 since the first purchase in 1991, Callaway said. The agency will probably continue to gradually get more of them.

“Like anything else, they were big, cumbersome and very expensive at first,” Callaway said. “It took time to catch on with officers, like myself, who were accustomed to using regular radar.”

The LAPD has 22 lidar devices spread among the city’s three traffic divisions. Valley Traffic has seven of them, which are rotated among 30 officers trained to use them.

Use of lidar in Valley Traffic over the last two years has resulted in safer working conditions and increased productivity, Meyer said.

Valley Traffic cops snag about 14 violators a day; officers equipped with lidar better those totals by as many as six speeding tickets, in less time, Turner said.

With those kinds of results on a limited basis, lidar has caught the attention of the top brass at the LAPD. At the behest of Chief Bernard C. Parks, Meyer said, the LAPD is trying to secure 80 more.

In the Valley, which has had an epidemic of fatal crashes and pedestrian fatalities, Meyer said, the goal is to equip every officer with lidar.

More broadly, he said, it is not just the speeder who is caught who gets an education. As the officer prepares a ticket, he or she is presumably providing an important lesson to those among the hundreds of drivers going by who might consider speeding.

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