According to the National Highway Traffic Safety Administration (NHTSA), unsafe operation by the driver is the leading cause of injury. Revealingly, the top five causes are all behavior related:

1. Driver distractions (Notably cell phones, laptops, GPS systems and other multi-tasking. The NHTSA estimates that driver distraction from all sources contributes to 25 percent of all police-reported traffic crashes.)

2. Driver fatigue

3. Drunk driving

4. Speeding

5. Aggressive driving

The IAIABC study breaks down injuries by industry and occupation. Unsurprisingly, truck drivers faced a disproportionately high risk of death, with relatively fewer non-serious injuries. Private passenger cars have lower fatalities, but nearly double the rate of non-fatal injury. Theoretically, this is because the size and mass of trucks protect occupants in low-speed collisions with other vehicles. However, trucks are susceptible to jackknifing and overturn, which are likely to result in fatal injury. In addition to high fatalities, trucking occupations tend to generate longer-duration claims and higher average cost of workers' compensation.

Class codes covering salespersons, messengers, and collectors generate the top-ranked share of claims -- and similarly costs -- for workers' comp vehicle accidents. Trucking codes fill three of the top 10 spots. It should be noted that these are absolute claim counts, not rates of injury per worker. The clerical code is the largest single employment code so, all things being equal, it would have a large share of accidents. The loss data simply illustrates that "safe" jobs generate lots of vehicle claims.

In general, vehicle accidents tend to have a worse claim severity than non-vehicle causes of injury; there are relatively few "medical-only" claims (about 61 percent) compared to all workers' comp claims (about 77 percent). Also, when there are medical-only claims, the severity of those claims is greater.

Vehicle injuries also had a far higher rate of permanent total and fatality workers' comp claims than claims overall. Likewise, the average severity of temporary total, permanent injury, and fatality is worse for vehicle versus non-vehicle claims. For example, NCCI researchers found that total severity for motor vehicle accidents in trucking (1997-2003) averaged close to $29,000, but for all other occupations it was just more than $16,000. And even though they make up only about two percent of all claims, vehicle accidents account for more than a fifth of the fatalities.

Neck injuries are by far the most-injured body part. Based on the injury codes in workers' comp claim reports, neck sprain and cervicalgia (pain in neck) were the first and second ranked codes, accounting for 15 percent of all vehicle claims. But those same codes amounted to less than two percent of all workers' comp claims.

To illustrate the relatively severe nature of traffic vehicle claims, it is interesting to note that they make up almost two percent of claims but represent more than 5.5 percent of total losses. The share of costs and claims due to vehicle accidents grew over the period 1997-2003. In the good news-bad news department, that injury rate is now declining, but less slowly than other workers' comp injuries, leaving vehicle accidents to remain a large source of workers' comp claims and losses.

However, workers' comp payouts constitute only a fraction of the costs of vehicle accidents. According to a study done by the Network of Employers for Traffic Safety, the combined cost of motor vehicle crashes to employers averaged $60 billion per year between 1998 and 2000. Those researchers found that medical expenses from motor vehicle crashes were $7.7 billion in 2000; another $8.6 billion was spent on sick leave and life and disability insurance for crash victims. Workers' comp costs, by comparison, averaged $2 billion per year over the same period.

In light of the dramatic cost to their bottom lines and the overwhelming toll on human capital, employers have a multitude of reasons to take at least the basic steps to learn more about risk factors and accident prevention techniques -- and few good reasons not to.

Founded in 1914, IAIABC is a not-for-profit trade association representing government agencies charged with the administration of workers' compensation systems throughout the United States, Canada, and other nations and territories. Find the complete article on traffic accidents at www.IAIABC.org/news.