The trend has continued during 1989-95. At night, street lights, headlamps and taillamps of other vehicles may distract the driver. Those hypotheses still sound reasonable. 35-36, and it is strongly confirmed by the present data. 6.19 Pennsylvania 1.63 5.76 Utah 4.70 7.82 5-State weighted average 1.75 6.07 Two hypotheses help explain the results.
Rural effectiveness is higher, though, in the three larger States.
The observed effectiveness is higher on wet roads than on dry roads in every State except Maryland. On wet roads, even if they follow less closely than on dry roads, they do not add distance commensurate with their reduced braking capability. In other words, the factors suggested above are negligible or cancel one another out. The 1989-95 data more or less continue those trends, showing perhaps slightly higher effectiveness in towaways than nontowaways and nearly equal effectiveness in PDO and injury crashes. The 4-State weighted average is somewhat higher in towaway crashes.