Last week we mentioned efforts to bring automated speed enforcement to ABQ, but until that happens we’re seeing more and more of these:

Speed trailers have popped up all over town, both City and County. Anecdotally, it’s great fun to grab some popcorn and spend an hour near a speed trailer/sign observing driver reaction as the numbers and red “SLOW DOWN” flash, but does data confirm that speed signs and trailers actually work in temporarily changing driver behavior?

With exceptions and caveats, yes.

For example, a 2003 study conducted by the Texas Transportation Institute at Texas A&M University, found the following:

Overall, average speeds were reduced by 9 miles per hour at the school speed zone. Elsewhere, the effect of the
(Dynamic Speed Display Signs) DSDS was less dramatic, with average speeds reduced by 5 mph or less, depending on the location tested. As expected, the influence of a DSDS was found to differ depending on how fast a motorist approached the DSDS. Those motorists traveling faster than the posted speed did appear to reduce their speed more significantly in response to the DSDS than did motorists traveling at or below the posted speed limit. The results of this project suggest that DSDS can be effective at reducing speeds in permanent applications if appropriate site conditions apply.

Speaking of data collection, unlike in prior years it is BB’s understanding that actual bona fide data is being compiled via today’s speed trailers (general traffic counts and speed only, nothing involving identification of individual driver behavior). Such data is particularly important at places like Central/San Pablo, where a new HAWK signal is going up (perhaps at the very spot of the trailer above). If the little gizmo above is tracking speeds and counts now, we can get a pre/post look not only at the driver behavior impact of the current speed trailer, but also the pending HAWK signal.

Running with that idea a bit, might it be possible that driver behavior will grow generally more cautious (i.e., slower) around HAWK signals IF they are placed in abundance and frequently activated? Also, does frequent HAWK placement have any impact on traffic counts (e.g., will all the HAWKs on Central motivate at least a few drivers to choose east/west parallel Zuni instead?)

My sixty seconds of Googling does not reveal a study concerning those particular questions; understandably, it seems most HAWK research currently centers on the very important question of driver compliance (e.g., this 2017 Delaware study) or lack thereof. Driver psychology (e.g., speed trailers) is so central to traffic safety, a disturbing observation when one considers the prevalence of mental abnormalities on display when humans operate multi-ton projectiles.