After 27 people died on Highway 37 from 1966 to 1970, transportation officials began trying experimental safety measures.
In 1971, the state added signs at both ends of 37 stating "Turn on headlights next 9 miles."
The "Daylight Test Section" joined nine others in the state. Those programs were instituted in areas suffering from a high number of head-on collisions on two-lane highways that connect to larger freeways. Highway 37 connects to Highway 101 and Interstate 80.
The word "test" was thought to give drivers a "positive psychological effect" and make them more alert. Keeping headlights on during the day, theoretically, would remind drivers of oncoming traffic.
Initially, law enforcement officials and politicians touted the new system, claiming it cut deaths by 90 percent. Further testing initially proved they were right, with accidents along 37 dropping 18 percent in a
However, while nighttime accidents drop, daytime accidents actually increased. Most of the deadly head-ons occur during daylight hours, a 1982 Caltrans study concluded. The study claimed motorists would either not realize the left-lane was for oncoming traffic or would try to pass other vehicles.