TECHNICAL 12-R-7
Trucks/Trucking: safety
Fig. 1: UGA study tracks log accident rates in Georgia, and contributing factors, over time.INTRODUCTION: Following reports in the late 1980s on the poor safety record of logging trucks in Georgia, researchers at the University of Georgia began compiling statistics on the number and causes of accidents involving log-hauling vehicles. We have reported results from our periodic updates to these data previously (see 92-R-68, 96-R-51, and 06-R-3), and here we provide a review of data from 2004-2008.
DATA AND ANALYSIS: Law enforcement officers who work the scene of highway accidents record data on the causes and types of vehicles involved. The Georgia Department of Transportation enters information from these forms (DOT-523) into a computer database that it maintains. We recently updated our statistics for 2004-2008 using funding from the Southeastern Wood Producers Association. These additional data gave us a complete record of truck accident statistics in Georgia for the previous 21 years. We used these data to identify trends in accident factors and to compare factors associated with accidents before regulation (1988-1991) to those seen in subsequent years. In previous reports, we separated logging tractor-trailers from logging trucks (straight frame vehicles); however, due to the current similarity between data for the two, we now combine them into a single category: logging vehicles.
RESULTS: Through 2003, mechanical failures were a factor in substantially fewer accidents than prior to training and regulations instituted in 1991. This trend has continued through 2008, with mechanical failure representing 5.0% of accidents in logging vehicles during 2005-2008 compared to 11.5% during 1988-1991 (56% reduction). Mechanical failure was a factor in 2.3% of accidents for other heavy vehicles, a 39% drop from the percentages reported from 1988-1991. Mechanical failure remains more common among logging vehicles than in the case of other heavy trucks, but the training and regulation continue to provide substantial improvements in safety. Examining the specific causes of the mechanical failures, brake failure is the most common cause of accidents, 
representing 2% of all logging vehicle accidents compared to 0.8% for other heavy trucks. While that is a substantial improvement compared with rates prior to 1991, when greater than 6% of accidents were caused by brake failure, brakes are still more than twice as common a factor as any other mechanical source. Slick tires, which are an easily inspected item, are a factor in logging vehicle accidents six times as frequently as in accidents of other heavy vehicles, a trend that has been consistent since 2000. These two items represent the key divergences in mechanical failure causes between logging vehicles and other heavy trucks. The factors contributing to logging vehicle accidents have changed appreciably since 1991 as well (see Table 1). Mechanical failure has fallen from the most common factor to the fifth most common. “Following too closely” is now the most common, followed by “driver lost control,” and “misjudged clearance.” These factors are similar to those experienced by other heavy trucks; however, improper lane change is the second most common factor for other heavy trucks, likely due to the greater proportion of travel time spent on multi-lane highways compared with logging vehicles.
LOGGING VEHICLE ACCIDENT RATES DECLINE IN GEORGIA
The improvements in safety resulting from a reduction in mechanical failures have remained fairly stable since the mid- 1990s. However, the rate of logging vehicle accidents per million tons hauled in the state increased through 2003 (see Fig 2). Since 2003, the rate of trucking accidents has been generally declining. The current rate (15.9 accidents per million tons hauled) is at its lowest level since 1999. This improvement in the overall safety of timber trucking is an encouraging trend. When compared against the accident rate for other heavy trucks in Georgia (reported as the number per million ton-miles), the trends follow relatively closely.