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As long as there have been drivers, there have been drivers who are driving too fast. And for just as long as there have been drivers who are driving too fast, there have been police officers trying to prevent drivers from driving too fast. Indeed, speed limits have been part of the American fabric since at least June 12, 1652, when New Amsterdam (now New York City) enforced a law prohibiting the riding or driving of horses at a gallop within city limits.

Brian Traynor, of the US Department of Transportation’s Office of Enforcement and Emergency Services, was kind enough to provide a colorful time line of speed enforcement in the twentieth century.

Hartford, Connecticut, lays claim to the distinction of imposing the first speed limit in the US – an 8 mph limit in the city and 12 mph in the “country” (suburbs). Once the notion of speed limits spread across the country, localities tried their hardest to invent methods to ensure their measurement of speed was precise. For when Hartford’s law was imposed, the only pursuit vehicle available to law enforcement was the bicycle. An officer on a bicycle was quite capable of nabbing the flagrant lawbreaker found careening around the city at, say, 10 mph, but was ill-equipped to nab those burning rubber at 40 mph.

Westchester County, New York, therefore, decided that trying to chase down a speeding car on a bicycle probably wasn’t the most efficient way of solving the problem, so it introduced the stopwatch as a means of measuring the average speed of a car between fixed points. Over the next few decades, different technologies would be used to calculate the rates: slide rules, preprinted look-up tables; and eventually, calculators.

Traynor reports a particularly colorful “speed trap” that was quite advanced for its era: “New York City Commissioner William McAdoo set up a series of three dummy tree trunks at one-mile intervals along the Hudson Drive. A police officer equipped with a stopwatch and a telephone was concealed inside each fake tree. When a car sped past the first station, the officer inside telephoned the exact time to the officer in the next tree. The second officer set his watch accordingly. When the car passed his post, he computed its speed for the mile. If the speed was above the limit, he telephoned the officer in the third tree, who lowered a pole across the road and stopped the car.”

Foiled by foliage!

Pity poor William Buxton. He was the first driver found guilty of speeding because of the high-tech device introduced in 1910: the “Photo-Speed Recorder.” This contraption combined a camera synchronized with a stopwatch and operated by taking pictures of a speeding car at set times.

Other devices were created primarily for speed measurement purposes rather than for enforcement. David Hensing, deputy executive director of the American Association of State Highway and transportation Officials said that the endoscope, invented by William Phelps Eno in the 1920s, consisting of two periscopes located at a known distance from each other, was a highly accurate gauge. And those mysterious air hoses that we drive over from time to time are usually used to measure speed for research purposes. They too, are highly accurate, but are generally not used to nab speeders, partly because, according to Hensing, “many drivers discern (that) two hoses over the roadway are a speed measuring device rather than simply a counting device.”

Law enforcement agencies started utilizing radar for speed citations after World War II, but at first the technology was almost as cumbersome as the “triple tree” strategy. Traynor reports: “Radar then used a graph as the permanent record of the speed reading. The radar unit was so heavy that a tripod or some mounting device was needed to hold it and the pen-scriber (graph printer); a station wagon was the usual transport-setup vehicle. Stops were usually made by calling the speed reading down the road (they had radios then) to a stop unit(s) or to chase officers at the setup site.”

What we did not realize until we spoke to quite a few traffic officials is that radar and even fixed-point calculations without radar were never the dominant mode of catching speeders. “Pacing” was. And still is.

The classic “radar speed trap” has been banned in California, so pacing is particularly important. If a law enforcement official sees a vehicle cruising at excessive speeds, the “pacing car” lies behind the offending vehicle and attempts to maintain the same speed. Unmarked police cars can sometimes stay alongside the car for long stretches without detection. Greg Manuel, commander of public affairs for the California Highway Patrol said that pacing is the easiest, most reliable, and most efficient means of nabbing speeders. How can an offender explain away an officer in court testifying to the fact that a 70 mph pace in a 55 mph zone had been maintained for one and a half miles? About the only possible defense is that the officer’s speedometer is broken. But the California Highway Patrol makes sure that speedometers are calibrated on a regular basis, usually once a year. So if the last calibration report confirms that the speedometer is “off” by one mph, the judge might knock off one mph from the charge.

California and many other states that don’t rely on radar use aircraft to detect speeders. Officers walk off a designated area with measuring tape and mark it with painted stripes, often at quarter-mile intervals. Airborne officers track the movement of speeders between these stripes, and then contact cruisers stationed down-stream from the marked section. Even states that ban “speed traps” often allow airborne speed detection, and usually go out of their way to give a warning to potential miscreants, as David Hensing explains: “Signs are frequently posted indicating speed limits are enforced from the air, and some states use airplane-shaped painted markings in lieu of a plain stripe to remind motorists of this possibility.”

These signs act as a deterrent, and might slow drivers as effectively as positioning marked patrol cars in the area. In most localities, judges will accept a law enforcement officer’s visual estimation of the speed of a vehicle. Greg Manuel claims that an experienced California Highway Patrol officer can estimate the speed of a vehicle within a few miles per hour.

(Submitted by Ed Booth of Chico, California)


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