In order to implement highway safety programs which are efficient and cost effective, it is necessary to develop programs which are targeted to identified problem segments. As reflected in traffic accident records and statistics, drivers behave differently on different road systems. Roads on the Interstate system, which have been engineered to increase driving performance, are the safest in the nation. The Interstate system is used by the same cars driven by the same drivers as other roads, yet the non-interstate mileage fatal crash rate is 2 1/2 times higher than the Interstate rate. In 1981, 92% of all fatal crashes in which the driver had alcohol involvement occurred off the Interstate system.

In examining both total fatal crash patterns and alcohol-involved fatal crash patterns by road system, it is evident that the most severe highway safety problem is on non-interstate arterial and collector roadways in rural areas at night. The majority of these roads were designed and built 40-60 years ago, and often do not provide enough visual information for safe driving performance. Low-cost modifications to the roadway environment are effective in reducing the number and severity of crashes. Promising new research indicates that this technology can be extended to mitigate the alcohol-impaired driving problem.

Targeted safety programs have proven to be effective at the national level. The Highway Safety Act of 1973, recognizing the magnitude of the problem on rural two-lane roads, established categorical safety programs directed to identified problem areas. These programs have resulted in annual crash reductions since their inception. State reports to the U. S. Department of Transportation document that in 1981 they reduced fatal crashes by 29%. Since traffic accident patterns vary from state to state, as well as by road system within a state, states need to undertake evaluation analyses similar to the national quantification to identify specific problem areas.