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Problem: Freeway entrance and exit ramp interchanges are the sites of far more crashes per mile driven than other segments of interstate highways, but the characteristics and circumstances of ramp crashes have been the subject of relatively little recent research., Method: This study examined a sample of 1,150 crashes that occurred on heavily traveled urban interstate ramps in Northern Virginia. Based on a review of diagrams and narrative descriptions from police crash reports, the most common crash types were identified and examined for different roadway locations and ramp designs and by whether at-fault drivers were entering or exiting the freeway., Results: About half of all crashes occurred when at-fault drivers were in the process of exiting interstates, 36% occurred when drivers were entering, and 16% occurred at the midpoints of access roads or on ramps connecting two interstate freeways. Three major crash types--run-off-road, rear-end, and sideswipe/cutoff--accounted for 95% of crashes in the study. The crash type most frequently associated with exiting was run-off-road, and the types most common with entering drivers were rear-end or sideswipe/cutoff. Crashes most common on ramps--run-off-road crashes--frequently occurred when vehicles were exiting interstates at night, in bad weather, or on curved portions of ramps. Speed was often a factor. Crashes occurring on ramp margins (where ramps or access roads enter or exit) were most commonly of the sideswipe/cutoff type. These often involved at-fault passenger vehicles merging from entrance ramps into the sides of large trucks already on the freeway. The predominant crash type on access roads was rear-end crashes; congestion was a factor in these crashes. Alcohol was a reported factor in a sizeable proportion of run-off-road crashes occurring on ramps (14%) and ramp margins (30%)., Impact on Industry: Candidate countermeasures for run-off-road crashes include geometric design changes to increase ramp design speed such as increasing curve radii. Speed-related crashes may be reduced by the use of speed cameras accompanied by publicity. Rear-end crash countermeasures could include surveillance systems that quickly detect unexpected congestion, incident response programs, and variable message signs to alert drivers to traffic congestion ahead. Countermeasures for sideswipe/cutoff crashes could include extending the length of acceleration lanes.

Problem: In the United States, teenage drivers have a higher crash risk and lower observed seat belt use than other age groups., Method: Seat belt use was examined for teenage (16-19 years) drivers who were fatally injured in traffic crashes occurring in the United States during the years 1995-2000. Vehicle, driver, and crash factors potentially related to belt use were examined. State differences in belt use rates among fatally injured teenage drivers were related to states' observed belt use rates for all ages and other state-level variables., Results: During 1995-2000, mean belt use was 36% among fatally injured teenage drivers and 23% among fatally injured teenage passengers. One of the strongest predictors of higher belt use for both drivers and passengers was whether the crash occurred in a state with a primary seat belt law. Belt use rates for 1995-2000 for fatally injured teenage drivers ranged from 20% or less in six states to more than 60% in two states. States with the highest use rates were those with strong primary belt use laws and those with high rates of observed belt use for all ages. Lower belt use among fatally injured teenage drivers was associated with increasing age; male drivers; drivers of SUVs, vans, or pickup trucks rather than cars; older vehicles; crashes occurring late at night; crashes occurring on rural roadways; single vehicle crashes; and drivers with BACs of 0.10 or higher. Teenage driver belt use declined as the number of teenage passengers increased, but increased in the presence of at least one passenger 30 years or older., Impact on Traffic Safety: It is suggested that to increase teenage belt use, states should enact strong primary belt use laws and mount highly publicized efforts to enforce these laws. Graduated driver licensing systems should incorporate strong provisions that require seat belt use by teenage drivers and passengers.