A resident of La Jolla, California persuaded the traffic board to block a speed limit increase on the grounds that the legally required measurement of the speed of free-flowing traffic measured the speed of free-flowing traffic.
To avoid biasing results of a routine speed survey the city turned off speed feedback signs. That’s what they’re supposed to do.
Speed survey rules are based on the observations that (1) the natural speed traffic is normally safest, (2) it’s impossible to enforce a speed limit below the normal flow of traffic. The rules say “the engineering study shall include an analysis of the current speed distribution of free-flowing vehicles.” The speed limit should be about 5 mph above the average speed.
Somebody complained the limit could be lower if not based on free-flowing traffic speed. If those signs were flashing at drivers, measured speeds might be slower and the speed limit could be lower.
That’s missing the whole point of a speed study. The rules assume a measurement of the natural speed of traffic. You could line the streets with traffic cops and measure a lower speed. You could send out pace cars. What purpose would that serve? That would be ignoring the safety research as well as the fact that compliance would be minimal.
But what if you didn’t care about the safety research and you were willing to have police just ticket anybody at random? Then you’d be a typical city councilor.
To cities the engineering study is not a safety tool but an impediment to posting the lowest possible number on signs. In most of America they don’t even pretend to follow the law or engineering standards.
Fraud has to be subtler in California where traffic courts will enforce the law. I heard San Jose pulls a trick like the one San Diego is planning — use visible enforcement to bring speeds down before reviewing a certain 35 mph speed limit that an honest study would raise to 45. Maybe it’s standard practice and most cities are smart enough not to admit it in writing.
I have seem similar dishonest “engineering” studies in Massachusetts where the state has to approve municipal speed limits. In Lincoln they boasted of sending “little old ladies” to drive slowly to bias results. Nearby Newton stepped up enforcement to generate fake speed data. A speed trap on Cape Cod was justified by a similar fraud.
The national 55 mph speed limit came with a requirement that states had to keep average speeds under 55. In reality traffic speed was well over 55. Part of the solution was to set up speed traps before official speed measurement locations. Drivers would slow down just long enough to be counted as obeying Nixon’s mandate. The Federal Highway Administration was supposed to cut off federal highway aid… but that would be putting itself out of business, so it decided to takes states’ lies at face value.
Back when speed limits were the exception, not the rule, best practice was to remove or cover up speed limit signs during a speed study, leaving no speed limit. The field data would go into somebody’s inbox (literally a box in those days). A few months later new signs would be posted. Drivers would hardly notice.
That was the good old days, when speed limits were thought of as a safety tool instead of a religious icon or a weapon.
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