In 2012, Texas A&M University’s Texas Transportation Institute conducted a study to see if EMCs cause traffic accidents. Research included data from the FHWA’s own Highway Safety Information System (HSIS), a comprehensive database of crash records from several states. They identified 135 cites in which EMCs had recently been erected. Researchers used the empirical Bayes method to perform a before-after statistical analysis of the safety impacts of what was called the on-premise digital signs.
The research team used digital-sign installation information provided by sign manufacturers to identify locations in selected states where digital signs had been installed in the 2006–2007 time frame (this time frame was selected to provide adequate numbers of crashes in both the before and after periods).
HSIS data was studied two years before and two years after the on-premise digital signs were installed. For example, if a sign was installed in 2006, the "before" period was calendar years 2004 and 2005, and the "after" period was calendar years 2007 and 2008. The surveyed area was 528 ft. (0.1 miles) before and after the signs. HSIS data was available for California, North Carolina, Ohio and Washington.
The researchers wrote: “The results of this study provide scientifically based data that indicate that the installation of digital on-premise signs does not lead to a statistically significant increase in crashes on major roads. The overall results show that there is no statistically significant increase in crash frequency after installing the on‐premise digital sign. Based on the analysis performed for this research effort, the authors are able to conclude that there is no statistically significant evidence that the installation of on-premise signs at the locations evaluated in this research led to an increase in crashes.”
For the full report, go to http://www.thesignagefoundation.org/Library.aspx.
Also, to read about the Federal Highway Administration's study of EMCs and traffic accidents, go to: