DPS 2009 Numbers Not All They are Cracked Up To Be

Local news outlets tonight are regurgitating DPS’ press release with 2009’s traffic statistics which show a significant decrease in crashes when compared to previous years. Naturally, the credit is all going to photo enforcement – completely ignoring other significant contributing factors and trends: fewer miles driven due to the economy and unemployment (and less-crowded roads), new, draconian DUI laws, stricter teen driver’s license laws, safer cars, improved roads, and more.

So we did some number crunching of their own, and the results are NOT surprising. Our neighbor Nevada, who isn’t using photo radar experienced a similar decline in crashes when compared to Arizona. Their data is available here, but unfortunately does not include December numbers. Still the numbers provide perspective. To arrive at these numbers, we summed the data from the Northern, Central, and Southern regional reports.

Arizona beat Nevada by only 5% in total crash reduction and 4% in road fatalities. Suddenly, the 26% reduction in fatalities isn’t the grand achievement DPS is trying to take credit for.

Another problem with the Arizona data is that the numbers are statewide for all DPS-investigated crashes. This includes thousands and thousands of miles of roads, but there are only 36 fixed camera locations and 40 mobile units distributed about the state, and the sphere of influence for the cameras is quite limited. The cameras can’t be credited for improvements in locations where they aren’t installed or frequently present.

In the past, DPS has released data strictly for camera installation locations. It’s suspicious that DPS resorted to reporting statewide numbers rather than location-specific numbers. Something tells us we’re not seeing the whole picture… Stay tuned.

And while we’re at it… Have you ever wondered why the state doesn’t follow the advice set forth in ADOT’s speed limit information page? Despite understanding that the 85th-percentile speed is the safest speed, most roads around the state are set far below this standard. Kudos to Utah for trying to comply with this standard and actually trying it with very positive results.


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