In most of the United States, a traffic intersection is considered to start at the painted stop line or at a crosswalk. In Arizona, an intersection starts at an invisible line defining the extension of a curb. Sounds like boring traffic engineer stuff, right? Except, the definition of an intersection matters if you enter one after the light turns red — especially if there's a photo-enforcement camera focused on your tail. So Arizona Governor Jan Brewer's veto of a bill that would have brought the state's definition in line with that prevailing elsewhere has dollars-and-cents implications.

As theNewspaper points out, the intersection definition in HB 2557 would have bought drivers a little slack:

Under Arizona law, drivers may enter an intersection on a yellow light. By moving back what constitutes the start of the intersection by 24 to 38 feet, vehicles have more breathing room to clear an intersection without getting a ticket. The bill has the same effect as extending the duration of a yellow light by 0.2 to 0.6 seconds, depending on the width of the intersection and the speed of traffic. The vast majority of straight-through red light camera tickets are issued in those first few tenths of a second.

Most drivers in the vast majority of states are accustomed to hitting the brakes at clearly delineated stop lines or crosswalks, It's the same standard from place to place, and easy enough to figure out. Arizona's variation from that standard catches drivers unawares and keeps the photo-enforcement cameras clicking. A few years ago, the Copper State's essentially unique idea of what constitute's an intersection raised eyebrows at the Federal Highway Administration, even when Tucson took the trouble to paint a confusing guess-what-I-am third line on the pavement:

Arizona law states that a driver facing a red light may not enter the intersection, which is defined as the prolongation of the lateral curb lines where the two streets meet. The transverse violation line and "WAIT" message are being used to identify the actual line a driver cannot cross without being in the intersection and thus in violation of the red signal under Arizona law. However, it is unlikely that drivers from other States who encounter these markings in Arizona would understand their meaning or intent.

Later entry into an intersection, plus confused drivers, equals money for Arizona governments and wel-connected photo-enforcement companies, who share the revenue.

Of course, Governor Brewer didn't cite revenue as the reason for vetoing a seemingly technical traffic bill. Nope — it's all about safety (PDF).

Local law enforcement officers have stated that the most dangerous place in city traffic is the intersection. This danger can only be heightened by increasing the time in which a collision may occur while simultaneously attempting to reeducate drivers concerning where the boundaries lie. The law enforcement community has bbeen very clear that widening intersections will increase the possibility of collisions.

Yeah. Can't have that carnage that's leaving piles of bodies under traffic lights everywhere else. It's not about the money, at all.