U. S. Department of Transportation
National Highway Traffic Safety Administration
HS 808 705
List of Tables
List of Figures
Perceived Crash Causes
As in 1994, each group was asked to make a list of factors they perceive to be major causes of crashes on the Capital Beltway. Then, each participant was asked to select up to three items from the list that he/she considers to be among the most important causes.
In the 1997 groups, unsafe driving behaviors continued to be the major concern of most participants. Driving conditions, including bad weather and traffic congestion, was the second most serious category of concerns in the 1997 focus groups, followed by roadway design and maintenance factors, trucks and law enforcement (or lack thereof).
There was a perceptible difference between the proportion of 1997 and 1994 participants who designated one or more unsafe driving behaviors among the top three causes of Beltway crashes. In total, the 1997 participants designated about two items each from this category, compared to about one item each among 1994 participants. Excessive speed, aggressive driving, inattention, unsafe lane changing and tailgating were the most frequently designated behaviors in the 1997 groups. The major difference between the 1997 and 1994 groups is that aggressive driving was designated by 38 percent of the 1997 participants, up from only 2 percent in 1994. Also, far more 1997 participants (48 percent) identified excessive speed as a major crash cause than 1994 participants (23 percent).
Interestingly, the aggressive driver groups designated speed as a major crash cause more frequently (65 percent) than the 1997 general driver groups (38 percent). As might have been expected, fewer participants in the aggressive driver groups (15 percent) identified aggressive driving as a major crash cause than participants in the general groups (53 percent). Another marked disparity between the two types of groups was that 35 percent of the aggressive driver group members designated unsafe lane changes as one of their top three items compared to none in the general groups.
There was not much overall difference between 1994 and 1997 with regard to the proportion of participants who blamed driving conditions for crashes on the Beltway. There was, however, a difference in which conditions received focus. In 1994, 44 percent of the participants named congestion as a major cause of Beltway crashes. In 1997, only 23 percent did. Conversely, 37 percent of the 1997 group members said that bad weather was a major crash cause compared to only 9 percent in the 1994 groups.
In aggregate, roadway design and maintenance factors comprised the top category of crash causes among 1994 participants (designated "major" by 97 percent). In 1997, however, the category declined to third rank, with only 33 percent naming design and maintenance items as major crash causes. While shared acceleration/deceleration lanes (called "merge lanes" by most participants) remained the top item and did not change much. Construction, lane markings signs and lane drops declined sharply as major concerns.
There was also noticeably less emphasis on trucks in 1997 than in 1994. In 1994, 20 percent blamed trucks as a major crash cause. In 1997, the proportion declined to 4 percent.
The following table shows the percentage of participants who designated each item as one of the three most important causes. If an item was listed as a crash cause but no participants included it in their three most important items, it is represented as 0 percent. If an item was not mentioned by a group, it is represented as "--" in the table. It should be noted that when items are aggregated, they can and sometimes do, total to more than 100 percent because each participant could select up to three items.
The following list of crash causes was compiled in the three trucking company groups. Interviewing conditions made it difficult to get each participant to designate his top three causes as in the driver groups, but it was accomplished in the group of dump truck drivers. The table shows the number of participants ranking each problem among his top three. In all other cases, the mention of each crash cause is shown as a check mark ().
Like other Beltway users, the truck drivers' list of crash causes was heavily weighted toward dangerous driving behavior. They were somewhat less inclined than other drivers to blame Beltway crashes on driving conditions but congestion was mentioned in every truck driver group. Roadway Design factors were mentioned fairly often in the trucker groups as they were among other drivers. Law enforcement (or the lack of it ) was mentioned more among the truck drivers than among other drivers.