Laser device takes on tailgating

     A growing number of law enforcement agencies are discovering the benefits of a new tool for an old traffic enforcement problem: following too closely. For years, traffic officers have struggled to bring tailgating violators to justice in courts...

Alternative technologies

     Other tailgate-detection products are offered, although availability in the United States may be limited.

     For example, Israeli company Driver Safety Systems (DSS) offers the Marom Traffic Law Enforcement System, which measures a vehicle's speed and detects tailgating. This front-end system observes traffic via two invisible infrared beams across a traffic lane with two retro-reflectors mounted in the road surface from a field unit mounted at the roadside or on a bridge. Each vehicle passing between the electro-optic head and retro-reflectors breaks the two beams and triggers the unit's computer to measure speed, acceleration, headway and vehicle length.

     The Marom system records a digital image of all vehicles exceeding pre-set limits.

     A German firm, Vidit, has a system that makes it possible to analyze precisely timed live video recordings of suspected tailgating by using clearly defined road sector measurements. Distances between vehicles can be calculated at the speed they were traveling and police officers can decide, on the basis of court-accepted evidence, whether or not an offense has been committed.

Seeing is believing

     Sgt. Eric Hansen of the Grand Prairie (Texas) Police Department would agree with Harsha. In one part of Texas, he divulges, drivers are allowed to drive up to 85 mph.

     "We know that following too closely had been a factor in many collisions," Hansen says. "In fact, 11 percent of all crashes in Grand Prairie in 2006 were tied to following too closely."

     Like so many police departments nationwide, Grand Prairie has wrestled with observing tailgating abuse, yet feels hamstrung with inability to prove it. "We're trying to catch the people that are driving aggressively but have not yet caused a collision to occur," Hansen explains.

     To ensure tailgating is tackled, an agency need not only observe and cite the violators, but it must be sure the court system will allow the evidence. For this reason Hansen took the extra step of orienting his local legal arm on the DBC's capabilities.

     Apparently, the interest in DBC was infectious. Hansen reveals that soon after the demonstration, word spread about the legal system's satisfaction with the device and other Texas agencies visited Grand Prairie and observed the DBC laser, with one agency investing in its own device.

     So, is the DBC helping to put the brakes on tailgaters? Only time will tell. After all, Hansen points out, this technology must be used on a wider basis, and the public must become more knowledgeable about it before DBC will make people afraid of being caught for tailgating. Meanwhile Grand Prairie PD seems to be off to a good start.

     "We've used the DBC since May 2007," Hansen offers. "Only one case has gone to court."

     Bob Galvin is an Oregon-based freelance writer specializing in law enforcement and public safety topics. He can be reached at

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