Effectiveness of Behavioral Highway Safety Countermeasures (2008)

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3Behavioral countermeasures considered in this document are derived primarily from Countermeasures That Work: A Highway Safety Countermeasure Guide for State Highway Safety Offices (NHTSA, 2007b). The report was intended to include all countermeasures relevant to state programs in the following areas: alcohol-impaired driving, safety belts, ag- gressive driving and speeding, distracted and fatigued driving, motorcycle safety, young drivers, and elderly drivers. Ex- cluded are measures already in place in every state (e.g., 0.08 blood alcohol concentration [BAC] laws). The original report did not include countermeasures involving pedestrians and bicycles, but they have been added for the 2007 update of that document. The present report includes these countermea- sures, with some adjustments (e.g., booster seat promotions, a new type of program, was added). The effectiveness of each countermeasure listed in Coun- termeasures That Work was assessed in terms of reductions in crashes or injuries, or improvements in some intermediate measure, such as arrests or successful prosecutions. The rat- ing categories were defined as follows: • Proven—consistent positive evidence from several high- quality evaluations, • Likely—balance of evidence from high-quality evaluations or other sources, • Uncertain—limited and ambiguous evidence, • Unknown—no high-quality evaluation evidence, or • Varies—different methods of implementing the counter- measure produce different results. The Varies rating was usually applied when there were dis- cretely different types of approaches in use (e.g., the coun- termeasure “alcohol sanctions” included license suspension, fines, and jail). These separate actions have been consid- ered individually in this NCHRP report. Considering sepa- rate actions individually in other cases has resulted in the elimination of the Varies rating. Otherwise, the Hedlund effectiveness ratings have been retained, with occasional adjustments and updates. For example, Countermeasures That Work (NHTSA, 2007b) included studies through June 2006; since that time, there has been enough new information on passenger restrictions for teenage drivers to rate them as Proven. In total, there are 104 separate countermeasures: 33 in the alcohol area; 13 for young drivers; 11 for occupant restraints; 10 for pedestrians; 9 each for bicycles and motorcycles; 7 for elderly drivers, and 6 each for distracted/fatigued drivers and for aggressive drivers/speeding. Countermeasures That Work (NHTSA, 2007b) also included information on implementation costs, which is used as a start- ing point in the present analyses. The cost ratings are defined as follows: • High—requires extensive new facilities, staff, equip- ment, or publicity, or makes heavy demands on current resources; • Medium—requires some additional staff time, equipment, facilities, and/or publicity; and • Low—can be implemented with current staff, perhaps with training; limited costs for equipment, facilities, and publicity. Information in Countermeasures That Work was presented by topic area (alcohol-impaired driving, safety belts, etc.). This NCHRP report cuts across topic areas. Here, counter- measures are classified according to their behavioral change technique (e.g., education, laws, enforcement). This report also extends the Hedlund work in providing metrics for the countermeasures classified as Proven. That is, where possi- ble, an indication of the effect size of the countermeasure is provided (e.g., 10% crash reduction), as well as the target population and likely duration of the effect. Information on C H A P T E R 2 Countermeasures

monetary costs, including benefit/cost ratios, is also provided whenever possible. One problem encountered in conducting this research was that high-quality evidence concerning effectiveness is often lacking. Ideally, for every countermeasure in use, it should be known if it was effective. That is not the case. Of the more than 100 countermeasures considered, about half are rated as Uncertain or Unknown. However, both the uncertains and the unknowns can be assessed in terms of whether they are likely to work, based on the princi- ples derived from those countermeasures known to work and known to be ineffective. This same procedure can be used to gauge the likely contribution of new and untried countermeasures. 4