Motorcycle Interactions with Potholes, Roadway Deterioration, and Debris - Part 2 (Potholes)

In addition to a longitudinal pavement edge, a motorcyclist could lose control and capsize due to interaction with the far face or edge of a pothole. The loss of control mechanism in this scenario could be a significant front wheel diversion or significant slowing of the front wheel that causes pitching. To cause either, the contact or collision between the tire and the far edge of the pothole would have to be of sufficient severity to cause such a diversion or slowing. The image below, which shows a pothole in a parking lot, graphically defines the “near edge” and “far edge” of a pothole. The pothole depicted in this figure would likely be traversable at most any speed. When evaluating a specific pothole and the potential for it to contribute to a motorcyclist losing control, it can be helpful to parse the pothole into regions, since different features of a pothole can have different proclivities to cause a motorcyclist to lose control. As an example, consider the second image below where the pothole is parsed into regions. In this example, the regions are bare dirt and alligator cracking. Other possibilities could be areas of loose material or asphalt chunks within the pothole, or a vertical edge at one of the extents of the pothole.

If a pothole contains a vertical edge perpendicular to the direction of travel, the following factors will determine the severity of the interaction between the tire and the edge: 1) the shape and depth of the edge in the area of contact; 2) the length of the pothole; 3) the dimensions of the tire and what portion of the tire first contacts the edge; 4) the inflation pressure and stiffness of the tire; and 5) the speed of the motorcycle. The influence of the edge characteristics on the possibility of a loss of control is illustrated in the figure below. This figure illustrates a motorcycle tire encountering three different edges at the far side of a pothole. The edge depicted in “A” illustrates an extreme case where the edge is completely vertical, and the depth of the edge is as large as the tire. A vertical edge of this magnitude could clearly cause significant slowing of the wheel, pitching of the motorcycle, and a loss of control. Few pothole edges will be so severe. The edge depicted in “B” is less severe both in terms of its shape and its depth. The potential for this edge to cause control problems is more ambiguous and depends on the dimensions of the edge relative to the tire and wheel. The edge depicted in “C” would be easily traversable and shows the other end of the spectrum from “A”.