Dueling statistics

As part of its fight with the state of Iowa over ticket revenue, Cedar Rapids released statistics on the effect of city speed cameras.

Until a judge stopped ticketing in May, cameras enforced a 66 mph speed limit on I-380. 67 would get your car a ticket in the mail.

Speed cameras still collect speed data while they aren’t allowed to mail tickets. According to the city, the threat of a ticket did reduce speeds. About 2% of vehicles were over the 66 mph limit in 2016, compared to 7% without tickets. At one site, 73% were exceeding the unenforced 55 mph speed displayed on signs in 2016, increasing to 87% without.

That’s according to the city which only measures speed at the camera locations, which are well-known to drivers.

Iowa State University researchers have their own sensors, which reported average speed 57.7 mph with tickets and to 58.5 without when cameras were not watching. That difference is probably within random variation.

It’s a familiar story. Drivers learn to slow down when passing cameras and speed up when they are safe again.

So far it doesn’t matter who you believe. Both the city’s and the state’s statistics are good news. With ticket cameras gone people can get where they are going faster.

Did the city’s interference with traffic flow have any beneficial effect?

Another familiar part of the story is, braking for cameras causes crashes. It happened in the United Kingdom and it happened in Cedar Rapids. According to the state DOT there were half as many crashes in the summer without tickets. Using incomplete data, Cedar Rapids police claim crashes were essentially unchanged.

Again, it doesn’t matter much who you believe. Both city and state statistics agree that letting drivers go as fast as they want is good. The only difference in the facts is how good. The city says there’s a big increase in speed at no cost in safety. The state says there’s a small increase in speed and a big increase in safety.

Most importantly to the city, there’s a big decrease in revenue. Cameras brought in $3 million per year. That’s why the city is appealing a judge’s order allowing the state DOT to remove speed cameras that do not improve safety.

If the judge’s order is overturned on appeal the Supreme Court has a second chance to kill cameras. It recently heard arguments in a case asking it to throw out the whole guilty-until-proven-guilty ticketing scheme.

The opinions expressed in this post belong to the author and do not necessarily represent those of the National Motorists Association or the NMA Foundation. This content is for informational purposes and is not intended as legal advice. No representations are made regarding the accuracy of this post or the included links.

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One Response to “Dueling statistics”

  1. Dr Jett says:

    This is the ongoing scam by cities and states to use taxation without representation to balance their budgets. ALL lawmakers should be put on straight commission and get paid to balance the budget first and cut out all of the waste like expensive funerals for cops.