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.
Location of Arizona Interstate I-10 between Phoenix and Tuscon.
View looking west along Arizona Interstate I-10 where the cable barrier suddenly terminates at a location approximately halfway between Tuscon and Casa Grande.
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.
Move Over Law Sometimes Creates Traffic Safety Problems
Moving over for stopped emergency vehicles can create rather than avoid traffic safety problems. A recent photo of the scene of a traffic collision on Highway 401 exemplifies one of the problems. The photo below shows that some vehicles have stopped on the right side of the highway. Drivers understanding that they must “move over” begin to squeeze into the left lanes. However collision-involved vehicles are also stopped in left lane. Must drivers then veer back to the right?
Is it better for drivers travelling through this accident site to move to the right, left or simply stay in the lane they are in? Is this Einstein’s Theory of Relativity?
The reality of traffic conflicts demonstrates how blindly moving over to the right because a law says so can create safety problems, not remove them. Moving over to the left in the above example could cause through traffic to collide with the stopped vehicles in the left lane or pedestrians who have exited the vehicles on the left. From this overhead view it would seem that the safest action would be to travel in the middle lanes. But drivers do not have such an overhead view when they are driving. Frequently, especially when there are large and tall trucks present, drivers cannot see well enough ahead to know which lane is best to drive in.
This is the paradox where “experts” have created a law expecting that it will fit every occasion yet it may only improve safety in some occasions while worsening safety in others. There are situations where drivers, fearing being charged under the Move Over Law, will make a lane change into a lane where it is not safe to do so. While some might blame such drivers, in many instances they cannot see stopped emergency vehicles until there is only a limited time to react because of situations caused by the blockage of a view by large tall trucks. It is also not always a safe approach to apply heavy braking because that in itself can cause traffic problems for drivers not expecting such an action.
The general problem is that the Move Over law can create traffic safety problems and further study is needed to see how those problems can be corrected.
Unprotected Concrete Pillars – What Roadside Protection Is Warranted?
A recent fatal impact of an unprotected concrete pillar of the Highway 402 overpass at Glendon Road begs the question what kinds of roadside protections are warranted to prevent such tragedies.
Impact of this unprotected concrete median on Highway 402 and the Glendon Drive overpass resulted in a questionable death.
There are standards that exist in Roadside Design Manuals that are generated in the U.S. and these standards are mimicked in similar manuals in Canada and Ontario. Similarly there are protocols for testing the kinds of roadside devices that need to be installed; the latest version of these protocols is called MASH, 2016 version, also a U.S. standard. The policies adhered to by Ontario’s Ministry of Transportation are generally unknown because of the secrecy with which they operate. The public’s right to be informed about the Ministry’s operations has been whittled down over the years making it more and more like a dark and secret society rather than a public department functioning in a democratic Canada.
Historically protection from impact generally considers how far the pillar is located laterally from the travel path of vehicles. At the Glendon Road site the pillar was likely located about 10 metres away from the road edge. Consideration is also given for the type road or highway such that roadways with a higher design speed need to have a wider band of protections on each side of the travel path.
Consideration is also given to the typical angle at which vehicles depart a roadway and this will vary depending on whether the road segment is straight or curved. It has generally been reported that about 20% of vehicles will depart at an angle not greater than 17 degrees. The basis for that belief has not been identified. A study of Highway 401 collisions conducted in the 1980’s by the University of Western Ontario Multi-Disciplinary Accident Research Team was presented by Zygmunt M. Gorski at an inquest to median cross-over collisions in 1989. That study showed that average departure angles were 13 degrees with the smallest being 3 and the largest being 36 degrees.
Consideration is also given to how far vehicles are known to travel after they depart a road edge. Historically it has been believed that only about 20% of vehicles travel a distance greater than 135 metres. The UWO Accident Research Team study showed an average distance of only 58 metres, the shortest being 22 and the longest being 104 metres.
Finally, it has been understood that only about 20% of vehicles travel a lateral distance of more that 9 metres from the travelled edge of the road. The UWO Accident Research Team study showed an average lateral travel distance of 8 metres; the shortest being 2 and the longest being 36 metres.
When these facts are combined a recommended “clear zone” is developed for different roadways.
With respect to Highway 402, it is believed to have a design speed of 120 km/h. The Glendon Road collision location contains a shallow right curve with a radius that is greater than 1000 metres and therefore it is recommended that the required clear zone not be adjusted to accommodate the presence of the curve. Its traffic volume (AADT) has risen from about 10000 in 1988 to over 22000 today. Thus it is well above the threshold to place the clear zone in the highest category. The result is that any obstructions within 10 metres of the roadway should have required protection from potential impact.
When the overpass pillar is at the threshold for protection there is a general consensus that engineering judgment should apply. This loose term is often included in various manuals of standards and guidelines. It simply means using one’s trained and experienced common sense. Applying that engineering judgment should have recognized that the traffic volume of Highway 402 had risen over the years and that the daily 22000 vehicles that passed through the Glendon Drive location was too large to allow the unprotected pillar to remain unprotected. The fact that no one raised the issue is because essentially no one outside of the select few who study roadway safety standards would be aware of what is needed and acceptable. An uninformed public cannot complain when it does not recognize that there is a need to complain. And a single death is only highlighted in the news media for a day or two before it becomes lost in the ever greater quantities of information about less relevant matters.
Highway 401 Truck Median Cross-over Near Chatham – Did it Occur?
Scant information on social media sites indicates that a transport truck may have crossed through the high-tension median cable barrier of Highway 401 near Bloomfield Road, Chatham, yesterday, March 12, 2019. A photo posted by Matt Lajoie shows the damaged left front wheel area of such a truck along with a comment: “It appears as if the truck blew a steer tire and lost control”. The photo can be seen below.
Did this truck drive through the median cable barrier of Highway 401 near Bloomfield Road?
Although there does not appear to be any significant damage to the truck, and injuries may not have occurred, there is a bigger issue here.
The Ontario Ministry of Transportation is completing the installation of a high-tension median cable barrier along the 118 kilometre distance between Tilbury and London, Ontario. There has been local concern about the effectiveness of this barrier versus a concrete Jersey-type barrier that exists throughout the length of Highway 401. Meetings have been held where the Ministry has explained the safety of that installation while local groups still remain concerned. It has been the opinion of Gorski Consulting that during this time of unease documentation of the in-service performance of the barrier should be made available to the public. This means that when the barrier is struck some information should be made available whether it has performed properly. But this is not what is occurring. As can be seen from this latest (possible?) incident, very little information is being passed on to the public. Indeed, if the pictured truck did pass through the cable barrier this should demonstrate a failure of the system and should be of concern. Failure to make that known to the public will not be seen well and will not generate the public’s confidence that the Ministry needs. The worst approach is to hide any failures.
At a minimum, officials who know what actually occurred should be prepared to respond on social media and quell any unwarranted speculation if it is in error. But silence on this issue is not going to bode well.
UPDATE: March 18, 2019; 0810 Hours
After further discussions and research it is believed that the high tension cable barrier installation had not reached the location where this incident allegedly occurred. It is still unclear whether the transport truck simply blew a left front steering tire and simply came to a stop or if it crossed the median as suggested on social media. It cannot be viewed as a minor incident if the median cross-over occurred as it would be just luck that a fatal collision would not have occurred.
Hwy 402 Fatal Impact of Unprotected Overpass Pillar – Review of Evidence
Police and news media have not discussed the details of how a female driver was fatally injured when her SUV struck an unprotected pillar of an overpass on Highway 402 at Glendon Drive. The following discussion will provide some of those details.
It was reported that at eastbound SUV was travelling on Highway 402 at approximately 0200 hours this morning when it entered the median and struck an “overpass”. That description does not properly identify that an unprotected concrete pillar existed in the median and, because there was no safety barrier in front of it, the SUV struck the pillar and the driver was killed.
The photo below is a view looking along the eastbound lanes of Highway 402 approaching the Glendon Drive overpass. Note how there is a right curve that could cause vehicles to enter the centre median. This would necessitate the installation of a barrier to prevent an impact with the pillars of the overpass that are located in the middle of the median.
View along the eastbound lanes of Highway 402 approaching the Glendon Driver overpass. Note that there is a slight right curve and therefore, without paying attention a driver could allow a vehicle to drift into the centre median. This is why some form of barrier is needed prevent such a vehicle from moving into impact with the pillars of the overpass in the background.
The view below is closer to the point of impact. The SUV struck the middle of the three pillars in the background. In the foreground a tire mark can be seen on the gravel shoulder and this was caused by the tires of the SUV.
The eastbound SUV travelled off the paved surface and impacted the middle of the three pillars of the overpass. In the foreground a single tire mark from the SUV is visible on the gravel shoulder adjacent to the yellow hazard marker post. The point where the tire mark exited the pavement was about 40 metres from the point of impact.
Turning around, the view below is looking back such that the SUV would be coming toward the camera. The SUV would have travelled a substantial distance through the right curve before exiting the pavement and entering the median.
Looking back so the SUV is approaching the camera, we can see the tire mark, in the foreground, on the median shoulder.
As the SUV entered the median there as a rise in the earth just before the overpass. The underside of the made contact with the rise, producing a large gouge, and this caused the vehicle to be vaulted in the air as it approached the pillars of the overpass. In the photo below the gouge in the earth can be seen just before the pillars. Judging by the width of the gouge the SUV was likely leading with its front end rather than sliding sideways.
As the SUV travelled through the median there was a rise in the earth which caused the underside of the SUV to gouge and and become vaulted in the air.
As shown in the photo below, there are no visible tire marks on the earth on the approach toward the struck pillar. This indicates that, after gouging the earth the SUV continued to be airborne up to where it struck the middle pillar.
There are no tire marks visible in the earth in the distance approaching the struck pillar. This means that the SUV was airborne as it approached the struck pillar.
Markings on the side of the middle pillar were indicative of a sideswiping motion. This indicates that the SUV likely did not strike the pillar centrally. Although no photos were made available by either the police or the news media it is likely that the contact of the pillar was made with the left side of the vehicle and the contact likely extended over a large portion of that left side. The photo below shows that the bottom portion of the markings are black and form a crescent. This could relate to contact by the left front wheel of the SUV.
The sideswiping characteristics of the scrapes on the side of the struck pillar indicate that the SUV did not make a central contact but slid past the pillar during contact.
Support for the conclusion that the SUV was vaulted in the air before impacting the pillar can be seen in the photo below. An investigator, 5 feet 10 inches tall, is standing next to the struck pillar and the black markings from the striking tire of the SUV can be seen at about the investigator’s shoulder level.
Support for the conclusion that the SUV was vaulted in the air at impact can be seen by comparing the height of the contact on the pillar to the height of the investigator standing next to it.
The median at this location is about 22 metres wide. The location where the visible tire mark exited the paved surface was 40 metres from the struck pillar. This would mean that the SUV travelled at an approimate 15 degree angle. When drivers who fall asleep or suffer some kind of medical episode their vehicle drifts off a road at a shallow angle of about 2 to 4 degrees. The departure angle is also affected by the presence of a curve so that, one can imagine, as a curve becomes greater so does the departure angle. Thus the 15 degree departure is not unusual for the present circumstances.
After impact with the concrete pillar the SUV continued to be airborne and made first ground contact about 24 metres past the impacted pillar. This first ground contact can be seen in the photo below.
The first ground contact, after the pillar impact, is shown in this photo. The vehicle continued to tumble along the median further into the background.
The typical evidence of a vehicle’s final rest position was found about 70 metres past the pillar impact. The photo below shows the evidence created by the towing operators as they pulled the SUV out of the median where it had come to rest.
Evidence of towing operating about 70 metres past the pillar impact can be seen in this photo with the overpass visible in the background.
In review, one must question why this collision had to result in a fatality. Clearly if a guardrail had been placed somewhere in the 40 metre distance prior to the overpass it would likely have deflected the SUV away from the concrete pillar. Fitch barrels or other devices located near the pillars might also have helped but the Ministry of Transportation had to understand that the embankment located just before the pillars would likely vault any approaching vehicles over such devices and a correction in the profile of the earth would have been required. Either way, this location is not some local street with a low traffic volume and the Ministry should have recognized that, some form of protection was needed in front of the pillars so that this tragedy could be avoided.
Yet, we can review the manner in which this fatal collision has seen minimal publicity by the news media and the public has been left uninformed. When inadequate road safety conditions like these exist it is essential that the public be made aware of the situation. Up to now there has been no public discussion of this inadequate safety issue and we cannot know whether the police did not notify the news media, the news median did not bother to inquire, or whether both are implicated in this lack of proper reporting to the public. It raises concerns that, when police and road maintenance personnel are both paid by the Ontario government which would be a defendant in any civil action, that these two entities are the only ones who are aware of the safety problem and they have the opportunity to hide it. When Highways such as the 401 or 402 are shut down for a police investigation no one independent to the Ontario Ministry of Transportation is able to examine the collision evidence before it is altered. When important evidence, such as the lack of as barrier, is kept from the public’s knowledge it must raise the question whether this has been done on purpose.
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