Last month I wrote the first of a two-part series on the relationship between driver demographics and safety performance. I began this admittedly unscientific project to address the concerns of an industry colleague who felt compelled to lower his company's minimum age requirement for drivers from 23 to 21, and reduce minimum driving experience from two years to one, because of what he considered the “diminishing” qualifications of the driver pool.
Using information from FMCSA's Analysis and Information web site, I found that younger drivers experienced somewhat higher accident and driver out-of-service rates than older drivers.
Unfortunately, there's no readily available federal data to help us look at the relationship between length of experience and safety performance.
However, I was able to use data collected by several industry colleagues who hire, train and manage new drivers. I had access to information about length of experience and the number and type of safety incidents, i.e., accidents, moving violations, motorist complaints and roadside inspection violations, for more than 3,000 drivers over a recent three-year period.
As the table indicates, “new” drivers, defined as those with six months of experience or less, do not seem to be disproportionately involved in safety incidents than drivers with more experience. In fact, drivers with 1-2 years' experience seem to have more safety incidents than their less experienced counterparts. But we would need a bigger sample to validate those findings.
I think more meaningful information can be determined by looking at the relationship between length of experience and specific types of safety incidents. The data suggests that accidents as a percentage of all incidents decrease with experience. They account for about 37.7% of all safety incidents for drivers with less than 3 months of experience, compared to 31% of all safety incidents for drivers with 4-5 years' experience.
In contrast, accident citations as a percentage of total safety incidents appear to increase with experience. We can see that traffic citations represent 11.4% of all safety incidents for drivers who have less than 3 months; experience. But for drivers with 4-5 years of experience, traffic citations account for nearly 20% of the safety incidents they're involved in. There is a similar relationship between driving experience and motorists' complaints.
Thus the data supports one of my hypotheses: Accidents account for a bigger piece of the safety-performance pie for inexperienced drivers than for drivers with more experience.
However, I didn't expect to find a correlation between “accident predictive” events (citations and motorist complaints) and length of driving experience. In other words, these incidents represent a bigger piece of the safety-performance pie for more experienced drivers than for less experienced drivers.
In the future, I think it would be important to look at the relationship between experience and accident cost to determine whether the more experienced drivers are involved in fewer, yet more severe, accidents.
Once again, even this informal analysis highlights the need for targeted safety interventions. For the inexperienced driver, we should focus on basic accident prevention techniques. For the experienced driver, we should focus on performance monitoring. This may help us do a better job of managing drivers who are most likely to be involved in serious crashes.
Jim York is the manager of Zurich Service Corp.'s Risk Engineering Transportation Team, based in Schaumburg, IL.
