Various persons and groups have resorted to a propaganda campaign portraying a direct relationship between travel speed and safety as the only issue of importance. In London, Ontario for example a local city councillor is petitioning for lowering City speed limits along certain road segments from 50 to 30 km/h because he read a City staff report that related vehicle travel speed to potential pedestrian injury.
The most common scenario is where the speed of vehicles in a school zone is related directly to the probability of injury or death. The saying often goes like this: A vehicle travelling at a speed of 40 km/h is likely to cause a certain probability of serious injury or death while the same vehicle travelling at 50 km/h is likely to cause an increase in that probability by some specific margin. Therefore, in order to create a safe school zone, all we have to do is reduce the speed limit from 50 to 40 km/h.
Many persons will recognize the fallacy in that logic but many also do not. It is the severity of the impact which dictates the consequences of a pedestrian impact, not the initial travel speed of the vehicle. Thus a vehicle travelling at 50 km/h may be braked before impact thus striking a pedestrian at 30 km/h. It should be obvious that the collision consequences would be much different if the same vehicle was travelling at 50 km/h and there was no braking, thus impacting the same pedestrian while still travelling at 50 km/h. Thus it is the “change-in-velocity” of the pedestrian’s body that dictates what injuries will be sustained, not the original travelling speed of the impacting vehicle. And there are other complicating factors in the relationship. The acceleration pulse is another. And the location of the application of the force on the pedestrian’s body is another.
As a further example, there can be a vast difference in the injury consequences to a pedestrian depending on the location of the head strike on the perimeter of the impacting vehicle. It has been known for decades that a head impact to the soft windshield or centre hood of a vehicle can result in less severe head injury than if the head impact is to a stiff portion of the vehicle such as one of the roof pillars or to the windshield header.
The photo below was recently submitted by the Peel Regional Police on their Twitter account, reportedly showing the damage caused by a pedestrian impact that occurred on May 13, 2019 at Winston Churchill Blvd and The Collegeway in Mississauga, Ontario. The damage at the bumper and hood regions does not match the description of a pedestrian impact and is more indicative of a cyclist, or something non-human, causing the lower-level damage. Never-the-less we can see the major impact to the windshield that would typically be caused by the “pedestrian’s” head. While it is difficult to discuss this result as beneficial as this “pedestrian” would likely have sustained life-threatening injuries, it is favourable to cause a head impact to the softer windshield than if the head impact occurred slightly to the right and against the stiff A-pillar. Thus examples like these demonstrate that the initial travel speed, and even the change-in-velocity of the pedestrian, often do not match the severity of injury because of the specific manner of contact that occurs.
Thus failure to inform the public of these complications amounts to providing erroneous information that does not result in any meaningful safety benefits.
Lowering speed limits is school zones to the unusual maximum of 30 km/h may cause a certain percentage of the driving public to reduce their speeds. But that percentage is likely the group that is already law-abiding and not the source of the problem. The group that is the source of the problem are those that are speeding, distracted and impaired, who have a history of disobeying speed limits, and who will continue to drive through a school zone at whatever speed they choose. Unless there is a substantial increase in police enforcement only a very small sample of these problem drivers will ever be captured and fined.
Various costly experiments have been conducted by municipal jurisdictions because travelling salesmen have approached them with ready-made solutions to school zone safety problems. An example of this occurred in the summer of 2017 when the City of London created reduced-speed zones of 40 km/h in various school zones and installed a series of in-road barriers as shown below.
One of the problems with these barriers is shown in the photo below. The barrier was placed at a curve in the road next to a bus stop. When a bus came to a stop at this location the lane was no longer wide enough for vehicles to pass because of the existence of the barrier. So vehicles began to steer into the opposing lane. However, because of the presence of the curve those drivers could not detect whether opposing traffic was coming. Fortunately the slow residential speeds did not cause any major collisions before the barriers were taken down. Yet the potential for a serious collision was induced by the erection of the barriers.
To test the effectiveness of the new 40 km/h maximum speed limit and in-road barriers Gorski Consulting conducted a multi-video camera analysis in August of 2017. Cameras were set-up in the 100 metre zone approaching the zone of reduced speed and a second set of cameras was set-up through the 100-metre zone of reduced speed. The findings indicated that the average of vehicles in the 50 km/h approaching the reduced speed zone was 49.2 km/h whereas the average speed in the 40 km/h zone was 51.4 km/h. In other words, vehicles travelled faster in the zone of lower speed, where the in-road barriers were located, than in the 50 km/h zone approaching that zone. Clearly the expense of installing the in-road barriers and installing the new signage did nothing for reducing the speed of vehicles travelling through the zone of reduced speed. Yet significant time and money was expended, not just in the City of London, but in several other cities where the vendors of the in-road barrier product moved to sell their wares.
Regrettably, many persons are given the authority to make safety changes in school zones by arbitrarily reducing posted speeds yet they have very little understanding that the environmental characteristics around the school zone may have a greater effect on pedestrian safety than the travel speed of vehicles. Without any training or experience with previous incidents, or how drivers and pedestrians perform, or what are the typical or extreme limitations of motor vehicles, these persons allow dangerous scenarios to continue to exist regardless of changes in posted speed limits.