There are many types of vehicles on the road, including multi-wheel trucks, smaller trucks, SUVs, sedans, smaller cars, and motorcycles. Research has shown that the mere fact that there are different types of vehicles on the road makes for dangerous driving conditions. This is a problem that appears to be resistant to interventions. The accidents are caused by larger vehicles not seeing smaller vehicles, larger vehicles taking over the right of way of smaller vehicles, and larger vehicles not able to gauge the speed and distance between the larger vehicle and the smaller vehicle. This isn’t, of course to say that larger vehicles are the cause of most motor vehicle accidents. Smaller vehicles have an equally difficult time judging the distances between larger vehicles as well as judging their distance.
The two vehicles that are known to be the most incompatible with one another on the road are automobiles and motorcycles. A crash between a motorcycle and an automobile generally yields significant trauma to the motorcyclist. Trauma can include closed head traumas, cervical trauma, chest and abdominal blunt trauma, pelvic fractures and tibial/fibular trauma.
The problem is that the same road conditions are interpreted differently by automobile drivers and those who drive motorcycles. There are simply different cognitive interpretations of the road by drivers of cars and drivers of motorcycles. This cognitive difference tends to get better when the individual is driving on fast roads, such as freeways and highways. This likely means that more collisions between cars and motorcycles occur on slower urban roads with more stop signs and stoplights. The other high risk areas are country roads and at junctions. These places generate stereotypical behavior that is unfavorable to motorists anticipating the presence of motorcyclists in the area.
One helpful thing is to include signs that warn drivers of events behind them as well as in front of them so they know when to anticipate the presence of hills and valleys that might hide the presence of a motorcycle. They also feel that practical measures of cross-mode training and route drivability.
The other issue with having different types of vehicles on the road is that some vehicles are less conspicuous than others. There has been some research that indicates that increasing the conspicuousness of smaller vehicles and motorcycles makes them easier to see and easier to judge things like speed and time to approach. Speed and time to approach are important when it comes to judging when to make a turn in front of the oncoming vehicle. If this is misjudged, the larger vehicle can turn in front of oncoming smaller vehicles, causing an accident.
The same is true of vehicles trying to cross a railroad track. Because trains are so large, they are perceived as moving slowly. Because they appear to move slowly, vehicles start to cross the railway, thinking they have enough time when, in fact, they do not. This is how many motor vehicle and train accidents occur and why motorcycle and automobile accidents tend to occur.