Speed detection systems get smart

It might be argued that speed limits are almost pointless because it is part of everyone’s genetic makeup, it seems, to speed. Similarly, drivers can’t act as though they are travelling each day on a German autobahn where there is no general speed...


It might be argued that speed limits are almost pointless because it is part of everyone’s genetic makeup, it seems, to speed. Similarly, drivers can’t act as though they are travelling each day on a German autobahn where there is no general speed limit, just an advisory one (estimated at 81 MPH). Then there are the sobering statistics: an often quoted one, from the National Highway Traffic Safety Administration, states that speeding is a factor in almost one-third of highway crash deaths. What’s more, a Louisiana Department of Transportation and Development study found 79 percent of vehicles on interstates were exceeding speeding limits. The study clocked many vehicles traveling as fast as 93 mph.

How about citations? The website TrafficTickets.com cites 41 million citations are issued by law enforcement for speeding each year.

All of this data points to the fact that law enforcement still has its work cut out regarding speed enforcement. The game changer is timely technology that rules the roadways in an effort to prompt speeders to let up on the accelerator.

Radar or lidar? Each has merit

Canvass 100 or more law enforcement agencies across the country and you’re likely to find some use only radar, others deploying just lidar, and still others using both speed enforcement technologies. Deciding which technology to use depends on your jurisdiction’s amount of traffic, types of highways and roads, and the extent of speeding infractions.

Radar measures the speed of moving cars by detecting a change in frequency of the returned radar signal caused by the so-called “Doppler effect,” whereby the frequency of the returned signal is increased in proportion to the car’s speed of approach. Radar can be most effective in traffic areas that are not too dense. The radar’s radio waves shoot out in a cone-shaped pattern that covers a very wide swath at ranges of up to 1,000 feet. The biggest drawback of radar can be that it will pick up excessive speeds of several cars, not allowing the officer to pinpoint a specific speed offender.

Lidar, which emerged in the late 1980s, uses pulsed laser light instead of radar waves. A lidar unit’s laser beam is very narrow and determines a vehicle’s distance and time (for the laser beam to reflect off the vehicle and bounce back to the lidar system) to calculate the vehicle’s speed. The chief advantage of lidar is that the user can rapidly obtain a speed reading for a particular vehicle, assuming the user has a direct sightline for that vehicle.

Lidar ideal for targeting high-speed zones

With speeding, old habits die hard or—as with some drivers who speed no matter what the risk—never at all. That’s one of the reasons Joe Manges, a traffic officer with the Grayslake, Il., Police Department, relies on technology to catch speeders and tries to change their urge to exceed speed limits. Grayslake is like many cities across the nation where stretches of highways cannot keep up with exploding traffic. The city has 25,000 residents, is primarily a residential area, and has several road arteries cutting through town that are only one lane in each direction. The result? Lots of gridlock. “A lot of people are moving in, and the county is slowly building up the roads (many residential streets), and that’s the reason for the gridlock,” Manges says. Accidents, mostly fender-benders, abound as drivers see gaps in traffic flow then race to catch up with the next pack of cars, but have too little reaction time and slam into other cars.

“We’ve increased our speed enforcement on the main road by simply being there,” Manges said. “We target certain areas at specific times of the day based on complaints and where speeding accidents happen most often.” Helping Manges and his fellow officers nab speeders is an LTI (Laser Technology Inc.) UltraLyte 20-20 laser device, with pinpoint accuracy in multilane traffic, and a laser beam that is approximately three feet wide at a distance of 1,000 feet away. Using the lidar laser, Manges notes “We can stand a thousand feet back (from an oncoming speeding car) and capture somebody’s speed. By the time they are up to one of our patrol units, we’re ready to stop them and talk about their violation. It’s very accurate,” and validates an offender’s speed, Manges adds.

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