While testing by Gorski Consulting showed that the westbound Highway 401 between London and Tilbury was generally in good condition, local safety problems were also noted. This is a problem when drivers expecting a good, smooth surface are suddenly faced with a local disruption which could cause a vehicle loss of control.

An example of these local variations in the road surface can been observed in a “spot” deficiency in the vicinity of 1 to 2 kilometres west of Merlin Road, a location that is just west of Chatham, Ontario. The four figures below, taken from Google Maps, show the specific location on Highway 401 where the road surface problem was detected.

Area of Merlin Road located south-west of Chatham, Ontario.

Specific location of Merlin Road along Highway 401 where a road surface problem was detected.

Overhead, Google Maps, view of the location along westbound Highway 401 where a road surface problem was detected.

This westbound view, from Google Maps, along Highway 401 shows the area of a small bridge crossing a drain where there was a disruption noted in the test vehicle’s motion.

The following views are taken from our video-editting program showing synchronized camera views as our test vehicle approached the noted bridge.

View, looking westbound on Highway 401 as our test vehicle approaches the area of the small bridge.

View approaching the small bridge.

View approaching the small bridge.

The figure below shows our test data taken on May 5, 2019, over a time of 30 seconds, travelling at approximately 111 km/h in the vicinity of 1 to 2 kilometres west of Merlin Road. The data at the extreme right end of the chart, emphasized by the large green oval, shows the area where our test vehicle passed over the noted bridge.

The green oval in this chart shows the area where the test vehicle crossed over the small bridge.

Selecting 12 samples of data taken around this upheaval it was noted that the standard deviation in the test vehicle’s lateral rotation was 0.0678 radians per second. This is much greater than the average lateral rotation over the full 30 seconds which was 0.0185 radians per second.┬áIt can be recalled that our sampling rate while conducting the testing was at 30 per second. So the 12 samples would represent a time just less than a half second. While this is a relatively small time it is more than sufficient to cause a notable disruption in the test vehicle’s motion.

Obviously there is little problem with this occurrence when the road surface is dry and bare. However that will not always be the case. There will be occasions when vehicles may travel on a wet surface, or even in snow or ice. In those special conditions of ice and snow the tire force will drop dramatically. As a result disturbances in a vehicle’s motion during such conditions of low tire force can create a scenario where demand approaches the threshold of the available tire force. Especially in those conditions where a longitudinal rotation may result in the lifting of the vehicle’s mass, and thus reducing the tire force, precisely at the same time as a lateral rotation is initiated. When traffic volumes may be well over 20,000 units per day the potential for a least one vehicle experiencing a stability problem per day in winter conditions is not an alarmist’s expectation.

When such problems occur it is extremely rare that they are detected. A loss of control of one vehicle may result in many instances where the vehicle simply moves into another lane or onto a shoulder without any damage or apparent consequence to that vehicle. Yet encroachments into an adjacent lane can cause reactions by nearby, unsuspecting drivers who may react unpredictably, especially if they are caught off guard. A loss-of-control may then be initiated in the nearby vehicle potentially resulting in a collision. The relevance of the road surface disturbance would rarely be detected and even more rarely would it be noted as a cause in any official collision reporting. Investigating police have no objective methods or equipment to document the severity of road surface problems other than riding over them with a police vehicle and noting that a disturbance in motion is caused. Such subjective observations by investigators who have minimal or no experience or training in the comparison of road surface problems cannot result in any useful detection of those problems.

In summary, while we have reported favourable results in our earlier discussions of the quality of the road surface along Highway 401 it needs to be emphasized that the data displayed in the Road Data webpage of this Gorski Consulting website is in terms of averages over longer distances and times. Although the results from “spot” problems can be extracted, like shown above, those spot problems are too numerous to show in a data file that must show results over long lengths of many roads and highways.