Graduated driver licensing in the United States: evaluation results from the early programs

BACKGROUND: Seventeen states enacted graduated driver licensing (GDL) programs that were implemented from 1996 through 1999 and for which evaluations are of interest. METHODS: We received evaluation results reported for six states for which data were available. Summarizing results is difficult in other than the most global terms because of differences in pre-GDL programs, differences in GDL programs, and differences in evaluation methodology. RESULTS: All states identified some crash reduction among teen drivers following GDL implementation. This positive effect was observed across different geographic regions, and with different GDL programs. Simple counts are down-fewer teens are experiencing crashes and becoming injured. After calculating crash rates to adjust for changes over time in populations or licensed drivers, reductions generally were still found. Population-adjusted risks of injury/fatal crash involvement of 16-year-old drivers in Florida and Michigan were reduced by 11% and 24%, respectively. Population-adjusted risks of any crash involvement of 16-year-old drivers in Michigan and North Carolina were reduced by 25% and 27%, respectively. Reductions in night (restricted hours) crash risk were impressive in Florida, Michigan, and North Carolina. A comparison state design was only possible in the Florida evaluation, and results showed greater crash reductions under GDL. Change-point analyses of Michigan's crash data trends over time provided additional support of GDL's effectiveness in reducing crashes. DISCUSSION: Taken as a whole, and including the preliminary findings from California, Ohio, and Pennsylvania, these reports demonstrate the early effectiveness of GDL in reducing the crash risk of teen drivers. The impact of these studies and others to come will guide future research, practice, and policy.     

Evaluating the impact of passengers on the safety of older drivers

PROBLEM: This study involved a quasi-induced exposure analysis of 4 years of crashes involving older drivers in the state of Kentucky. METHOD: Single- and multivehicle crashes were disaggregated according to the number of passengers: (a) no passenger, (b) one passenger, and (c) two or more passengers. RESULTS: Overall, the presence of two or more passengers was found to negatively impact the probability that drivers 75 years of age or older were at fault in crashes. Several potential factors were studied for interactive effects with passengers: vehicle occupant gender mix, time of the day, road curvature, grade, and number of lanes. The negative impact of passengers increased for some geometric road conditions. However, older drivers were found to be safer at night when carrying two or more passengers. The presence or absence of passengers was not found to affect the 65- to 74-year-old driver group. Groups of male vehicle occupants with a 75+ male driver were found to have high single-vehicle crash rates. IMPACT: These results are among the first to directly consider the effect of passengers on the crash-causing propensity of older drivers and the findings suggest more work is warranted to consider causes for the crash rate differences.     

Effect of territory quality on intrusion rate in nonbreeding hummingbirds

Summary Experimental reductions of productivity on feeding territories of Anna's hummingbirds (Calypte anna) decreased intrusion rate. This trend contrasts with the absence of strong correlations between intrusion rate and productivity in previous experimental studies. Consideration of sample sizes, productivity rates, and time-dependent influences on intrusion rate (e. g., day-to-day changes in weather) indicates that this difference resulted from the more natural spatial distribution of artificial flowers used in this study. Offprint requests to: P.W. Ewald     

Torpor and basking in a small arid zone marsupial

The high energetic cost associated with endothermic rewarming from torpor is widely seen as a major disadvantage of torpor. We tested the hypothesis that small arid zone marsupials, which have limited access to energy in the form of food but ample access to solar radiation, employ basking to facilitate arousal from torpor and reduce the costs of rewarming. We investigated torpor patterns and basking behaviour in free-ranging fat-tailed dunnarts Sminthopsis crassicaudata (10 g) in autumn and winter using small, internal temperature-sensitive transmitters. Torpid animals emerged from their resting sites in cracking soil at ∼1000 h with body temperatures as low as 14.6°C and positioned themselves in the sun throughout the rewarming process. On average, torpor duration in autumn was shorter, and basking was less pronounced in autumn than in winter. These are the first observations of basking during rewarming in S. crassicaudata and only the second direct evidence of basking in a torpid mammal for the reduction of energetic costs during arousal from torpor and normothermia. Our findings suggest that although overlooked in the past, basking may be widely distributed amongst heterothermic mammals. Therefore, the energetic benefits from torpor use in wild animals may currently be underestimated.