The advent of digital technology is slowly bringing change to traffic safety enforcement. Digital cameras and radar guns, combined with software that can recognize license numbers, can remove the need for having officers on the roads to enforce speed limits—as well as limit the instances where said officers get talked out of issuing a summons or fail to show up in court. Red light cameras provide an equally reliable addition to the revenue streams for municipal governments, but they have a far more complex relationship to public safety, which has led a number of states to ban them. Now, some cities in Texas, where a ban of this sort included a grandfather clause, are committing themselves to long-term contracts with the camera provider in order to escape the ban.

Ostensibly, traffic laws are all about public safety, as they prohibit drivers from a variety of behaviors that correlate with increased risk of accidents. And, in the case of speed cameras, the relationship should be pretty straightforward. Assuming that the speed limit on a given road is set based on the road's layout and prevailing traffic conditions, anything that keeps drivers from driving too far above the speed limit should benefit public safety. The fact that they bring in a steady stream of fines is just an added bonus.

The situation is much murkier when it comes to the speed camera's close cousin, the red light camera. The device's public safety justification seems clear up front—keep people from running red lights—but the pattern of their actual deployment suggests their focus is really on generating revenue. It has been argued that the surest way to increase safety at red lights is by extending the yellow period; in most cases, lights are run within the first second after they turn red. Installing the cameras does appear to change driver behavior, but its a bit of a mixed bag, as in one town in Texas, where accidents dropped only slightly due to a large rise in rear-end collisions.

But the cameras are generally run by private companies, which have little interest in installing them on red lights where violations are infrequent. For example, the company that installed cameras for Chattanooga, Tenneessee would only install them on lights that have a yellow time of less than four seconds, even though state law mandates that the minimum yellow time is 3.9 seconds. Extend the yellow light time, and you might limit not only accidents, but also the revenue provided by the cameras. Overseas, it seems there has been at least one case where cameras were deployed on lights rigged to change rapidly.

The fact that there aren't hard numbers to base these arguments on suggests that many towns are leaping into the use of cameras without ever bothering to look into their safety implications. Denver, for example, had a contract that mandated the reporting of statistics from the cameras, but the city never bothered to ask for them.

As a result, a number of states have now banned their use. To be fair, based on legislative arguments over speed cameras, the bans may have been as much the product of the fact that state legislators don't want to be caught by them, but the questionable ethics of the red light cameras undoubtedly helped them justify their decision.

But cities aren't content to see a source of revenue slip from their grasp, especially in the current fiscal environment. A site called theNewspaper.com, which tracks the politics of traffic laws, is reporting that some cities in Texas, which banned the installation of new cameras but grandfathered them in existing contracts, are attempting to evade the intent of the legislature. When faced with the prospect of having their existing contracts with a camera supplier gracefully expire when they run out, Arlington and Southlake are locking themselves into long-term contract extensions. Southlake has extended it for 20 years, by which point technology may have made the whole issue irrelevant.

Apparently, a similar thing happened when Montana passed a bill with exemptions for existing contracts, and the Montana legislature responded by passing a bill that stripped out that exception.

Rather than taking on the legislature, the cities might want to consider doing what they should have done in the first place: perform an analysis that shows that a specific combination of yellow light times and red light cameras actually improves public safety. Given hard data, it might be possible to convince the state that the cameras make sense in ways other than filling out the municipal budget.

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