Police traffic stops near busy or high speed roadways are a genuine danger. Mainly to the officer, but also to all traffic in the vicinity. A “Move Over” law has been enacted in Ontario that is an attempt to make such stops safer. Unfortunately new dangers are created when vehicles move over and slow down on the approach to a stopped police cruiser. There has always been a need to study these incidents and improve them.

A recent photo shown on an OPP Twitter account showed a reasonably safe instance, as shown below.

This example of an OPP traffic stop is about as safe as can be. But such stops can never be viewed as sufficiently safe.

There are several features in the photo that merit mention. Firstly, the van that was stopped moved over substantially to the right such that there is almost a full vehicle width between its driver’s side and the painted, white edge line of the road. Such lateral clearance from moving traffic is always desirable for obvious reasons.

Next, the OPP officer’s vehicle is an SUV and the large mass of this vehicle makes it better “blocking vehicle” than a typical police cruiser. The officer has also done the proper action of placing his SUV closer to the edge line than the stopped vehicle. This is an important safety issue because, as can be seen from where he is standing, he body is protected, to some degree, from potential passing vehicles that might veer toward him.

The faster that vehicles travel the more difficult it is for them to change their lateral position and angle in a given distance. Thus the police officer was correct in placing his SUV rather close to the back of the stopped vehicle because this will lessen the opportunity for faster-moving vehicles to penetrate, laterally into where he is standing. If he had placed his vehicle further back then there would be more opportunity for such faster vehicles to move laterally into where his is standing.

There would have been some advantage gained however if he had placed his SUV further back. This is because, if the SUV was struck, it would require that the SUV be pushed a longer distance before reaching the officer’s location. During that post-impact travel distance the SUV would be slowing down and, if the officer was struck by the SUV, the impact would generally be less severe. So there are trade offs to be considered.

By placing the SUV closer to the rear end of the stopped vehicle there is an advantage in that, if the SUV is struck, it will have less chance to rotate and miss contact with the vehicle ahead. It is important to recognize that, by striking the vehicle ahead the SUV loses its post-impact speed. This results in a lessening of the impact severity should the officer by struck by that SUV. In a sense it is adding additional mass to the blocking effect of the SUV and thus helps in protecting the officer when an impact occurs with the vehicle ahead.

In many instances when the two stopped vehicles are positioned as they are, there is a benefit gained when the impact force is not applied directly at the centre-of-gravity of each vehicle. This benefit is in creating rotation of each vehicle and this rotation helps in reducing the post-impact speed of each vehicle when the wheels of each vehicle have a “sliding sideways” component. If the wheels each vehicle are simply rolling forward that “rolling resistance” is very small and there is often very little slowing of the vehicles post-impact. So this non-central impact to each vehicle is another safety benefit. So it is important for the officer to have positioned the SUV at the offset position that he did with respect to the vehicle ahead.

Looking at the composition of the traffic in the lanes, it is obvious that this is an arterial roadway and not a high speed freeway. While some arterial roads may have posted speeds of 80 km/h, most have lower posted speeds. So this is an advantage. If this had been a high-speed freeway then the danger to the officer would be exponentially higher.

Furthermore, looking at the composition of the traffic one can see that it is made of passenger cars and LTVs (i.e. Light Trucks and Vans). That is a safety  benefit. Generally the vehicle that might strike the police SUV would be of a similar mass and that makes a huge difference in the post-impact results in terms of the post-impact speeds of the SUV and the other stopped vehicle.

The lack of any heavy trucks in this view is of great benefit, not only because of the mass issue, but also because of the visibility blockage that occurs whenever large trucks are in the vicinity. The driver of a passenger car or LTV who is travelling in regular traffic conditions is often positioned too close to the rear of heavy truck¬† and that driver’s vision is greatly reduced with respect to events that may be occurring or existing ahead. In some unfortunate incidents the drivers of such vehicles change lanes to the right without realizing that a police vehicle is stopped in that right lane resulting is potential deadly consequences. Similar issues arise when the driver of such a smaller vehicle is positioned adjacent to the large truck in the lane beside them. When there is a high percentage of heavy trucks on the road they can be bunched together and create and effective visibility wall preventing the driver of any smaller vehicle from seeing anything beyond that wall. Overall, visibility obstruction is a major issue whenever smaller vehicles are mixed with heavy trucks.

For many previous years there were major concerns with respect to the safety of police officers when their vehicles have been struck while stopped along major roads and highways. When police cruisers were primarily of the Ford Crown Victoria type there were many incidents of a rear-ended police cruiser catching fire as the gas tank was ruptured. Installation of protective bladders and other adjustments reduced those occurrences. However it is difficult to protect any passenger car occupant while it is stopped and struck by a heavy truck travelling at highway speed.

Ultimately a police traffic stop next to a high speed highway or freeway is never a safe situation in the scenarios that presently exist. Some safety benefit can be obtained by making every effort to position stopped vehicles as far away from the through traffic lanes. Unfortunately that is not always possible as police sometimes must place a cruiser in a live lane, for example, to protect persons that may be in that lane from a previous collision. Whether it is a struck pedestrian or a person trapped in a heavily damaged vehicle, there are instances where police cannot move persons off the travel lane into a safer location. In the early moments when through traffic has not built up to a stop or crawl the situation can be very dangerous. Lights and sirens may not be sufficient. As mentioned earlier, in the vicinity of heavy trucks visibility can be blocked. Sirens may be difficult to hear in the noisy realm of a busy highway.

It needs to be recognized that the danger posed to officers at a traffic stop are great. More education and publicity focused on the general public’s appreciation of the dangers may be of some assistance. However police also need to be properly trained and understand those potential dangers. When those dangers are too high they must consider aborting such a stoppage or make quick adjustments to the scenario to create a safer situation. The lives of those officers depend on an informed knowledge about the unique circumstances that each scenario may present.