Arizona Concludes Median Barrier Less Safe Than No Barrier

An Assistant Director of Transportation for Arizona, Steve Boschen, believes Interstate I-10 near Tuscon “…is actually much safer without barriers”. He states further:

“If there is an incident, the vehicle has a better chance at stopping once it hits the dirt median. We know that barriers are hazards. There are four times as many fatalities with a barrier than without them”.

As a result Arizona will not be installing barriers on the Interstate when they complete widening the highway between Tuscon and Casa Grande later this year. Decisions like these have implications toward the installation of the median barrier on Highway 401 between London and Chatham in the Canadian Province of Ontario.

Boschen’s conclusion comes despite comments from a local news reporter, Heather Smathers, of the Casa Grande Dispatch newspaper, who claims that “The exact numbers of cross-median crashes …is somewhat hard to quantify”. This belief is echoed by a traffic safety engineer with the Arizona Transportation Department, Kerry Wilcoxon, who explains that Arizona crash reports account for the first harmful event such as speed control and if that speed control occurred before the median cross-over then the incident is not recorded as a crash.

GoogleMaps images show that in the 95 kilometre distance between Tucson and Casa Grande Interstate 10 contains a cable barrier in the first 45 kilometres westward from Tucson. In this distance the median is only about 8 to 10 metres wide. Then the barrier stops abruptly. It is not clear whether this cable barrier is being removed during the widening of the highway.

The median width west of Tuscon is comparable to the 8-metre-wide median that used to exist in the 1980s along the stretch of Highway 401 between London and Woodstock before a concrete Jersey barrier was installed. In the 1980s there was considerable controversy with respect to the number median cross-over fatalities that were occurring and this resulted in an inquest in 1989 and the subsequent building of the median barrier.Much of Highway 401 between London and Tilbury, commonly referred to as “Carnage Alley” has a median width of approximately 12 metres. Yet the Ontario government is installing a high tension cable barrier along this 118 kilometre distance while also giving verbal assurance that a full, concrete barrier will be installed in the near future.

The news article written by Smathers referred to a 2017 research study by a graduate student from the University of Iowa who found that “…median cables reduced fatal crashes by 51.3 percent, however, the overall crash rate increased by 80.4 percent, driven ‘by an increase in property-damage-only crashes'”. However those conclusions may not consider that, reported property-damage-only increased because there was an impact to the barrier and therefore damage was caused that needed to be reported. However it is well-known that many property damage collisions do not become reported when they do not involve damage to public property. In fact a nine-year study by Gorski Consulting at a specific site in London, Ontario has shown that over 80% of collisions, which are predominantly single-vehicle, loss-of-control incidents, do not become reported to official agencies such as police. In many instances, if a vehicle is still driveable, the driver will simply drive away. Thus what may be happening with the Arizona data is that property damage collisions are not actually increasing in numbers, they are just being reported at a higher percentage because drivers cannot just driveway without leaving the tell-tale signs of a collision because damage has been caused to the cable barrier.

The negative opinions of administrative officials from the Arizona Department of Transportation regarding median barriers should raise some concern. It is not clear whether they understand how the data they rely upon was collected and how various conclusions from investigations along with the coding conventions for reporting collisions can lead to erroneous conclusions. In some areas of Interstate I-10, for example, the median about 84 feet, or over 25 metres. With such wide medians there is a lessened opportunity for cross-median fatalities for the obvious reason that the median is too wide. Furthermore, when concluding that there are four times as many fatalities with barriers as there are without, a bazaar comment in itself, there is no clarification that all roadside barriers  are not the same. Such that an impact to the guardrail barrier or its terminal could be coded the same as an impact to a cable barrier or a concrete Jersey barrier. Certainly if the bazaar conclusion that barriers “cause” four times more fatalities were true why would roadway authorities worldwide be installing expensive barrier systems? It is these kinds of unusual comments that need to be exposed to the public that is not capable of discerning  what information is fake and what is real.