Subjective statements often suggest that electronic message centers (EMCs) cause traffic accidents because they are distracting. Yet, is there any empirical evidence that documents this theory?
In 1980, the Federal Highway Administration published its "Safety and Environmental Design Considerations in the Use of Commercial Electronic Variable-Message Signs" study, which was hugely inconclusive. It conducted the study to support its theory that electronic signage (with changeable messages) caused traffic accidents, but couldn’t generate supporting data.
In March 2011, the FHWA released a study entitled “Driver Visual Behavior in the Presence of Commercial Electronic Variable Message Signs (CEVMS)”, which is another name for EMCs. Two tests were each conducted in Reading, PA and Richmond, VA. It also showed no evidence that electronic billboards cause accidents, as indicated by the following:
-The presence of digital billboards did not appear to be related to a decrease in looking toward the road ahead.
-According to the National Highway Traffic Safety Administration (NHTSA), safety concerns arise when a driver’s eyes are diverted from the roadway by glances that continue for more than 2.0 seconds.
-The longest fixation to a digital billboard was 1.34 seconds, and to a standard billboard, it was 1.28 seconds, well below the accepted standard.
-When comparing the gaze at a CEVMS versus a standard billboard, the drivers in this study were generally more likely to gaze at a CEVMS than at standard billboards.
- The FHWA study adds to the knowledge base but does not "present definitive answers" to the questions investigated.
The study states: “In general, drivers devoted more glances at CEVMS than at standard billboards; however, there were no significant decreases in the proportion of time spent looking at the road ahead (i.e., eyes on the road) that could be directly attributed the CEVMS at the measured luminance and contrast levels.”
Glances away from the forward roadway of greater than 2 seconds or 1.6 seconds’ duration have been proposed as indicators of increased risk of crashes. In the current experiments, there were no long glances at billboards meeting or exceeding 1.6 seconds. The longest glance at a target billboard was less than 1.3 seconds in both studies. Glances with a duration of 1 second or greater were rare: there were 5 in Reading (0.47% of the glances to CEVMS) and 7 in Richmond (0.78% of the glances to CEVMS). All of the glances greater than 1 seconds were to CEVMS.
The full study can be viewed at https://www.fhwa.dot.gov/real_estate/oac/visual_behavior_report/review/cevms2.pdf
A shorter article about its highlights can be found at http://www.nxtbook.com/nxtbooks/STMG/sott_201403/index.php#/44
Additionally, Texas A&M specifically studied EMCs and "before" and "after" traffic-accident data in 2012. For that full story, go to https://fasi.squarespace.com/config#/pages/570bae5cd210b89ef1a6a42a|/universitiesblog
Similarly, in 2010, Tantala Associates, a consulting/engineering firm, conducted its fourth study about the relationship between traffic accidents and electronic signage on billboards. Most recently, Tantala examined eight years of law-enforcement records that documented 35,000 traffic accidents on state and local roads around Reading, PA, to determine accident rates near 26 digital billboards. For the first time, the Empirical Bayes Method predictive tool was used to determine if accidents near digital billboards are inconsistent with what is statistically predicted. The answer: Digital billboards are “safety neutral.”
In 2008, Tantala investigated more than 60,000 traffic accidents in Cuyahoga County (Cleveland) Ohio for an eight-year period, before and after EMC billboards were installed. Accidents in the county, as a whole, had decreased in the last four years. Accidents where digital billboards were visible also decreased.
In Rochester, NY, Tantala reviewed police records documenting 18,000 traffic accidents that occurred within a mile of digital billboards over a five-year period, and in Albuquerque, it reviewed police records documenting traffic accidents that occurred within a mile of 17 digital billboards over a seven-year period. The studies showed no statistical correlation between digital billboards and accidents.
The January 7, 2014 edition of The Hill, a Washington, DC newspaper, included the following:
“Drivers are not distracted by digital billboards alongside roads, according to a study conducted by the Dept. of Transportation. The study, which was released by the Federal Highway Administration (FHWA), found that drivers are not any more likely to be distracted by digital billboards than stationary signs.
‘On average, the drivers in this study devoted between 73% and 85% of their visual attention to the road ahead for both (CEVMS) and standard billboards,” the study said. "The range is consistent with earlier field-research studies. In the present study, the presence of CEVMS did not appear to be related to a decrease in looking toward the road ahead’.”