Discussion

The results of the observational surveys presented here suggest that belt usage is lower at night than during the day. These results are similar to those reported by Chaudhary et al. (2005b).  Day/night belt use differences were consistent for men and women, for drivers and passengers, across road types, and for urban (inside city limits) and rural locations. The results of this study also suggest that the day/night belt use difference exists across vehicle types.

Chaudhary et al. (2005b) found urban versus rural differences in the day/night gap for seat belt use in Connecticut. This effect was not seen in New Mexico, but it should be noted that what is considered “rural” versus “urban” for the State of Connecticut may be very different than the New Mexico areas inside city limits and those outside city limits.

The statewide nighttime belt use survey in the State of Connecticut indicated that the gap between day and night belt use may be reduced immediately following CIOT (Chaudhary et al., 2005b).  It is important to note that the current study included a single wave of observations conducted immediately after the end of New Mexico’s CIOT program.  Thus, it is possible that there is a bigger difference between daytime and nighttime belt use during other times of the year.

The seat belt use figures reported here cannot necessarily be considered descriptive of the entire State of New Mexico in the same way that the reported statewide belt use figure is representative.  There is no weighting of the site-by-site results, which would be necessary to make them representative of the whole State. This is not to say that these results would not be expected to be the same for the State as a whole.  Indeed, the similarity of these results to Connecticut’s results and the fact that the observation sites were chosen statewide to be representative (albeit when weighted appropriately) suggest that the results are likely indicative of a Statewide day/night difference in seat belt use.

There may be some combination of at least two factors behind the lower belt use at night. First, people who wear seat belts during the day may be less likely to buckle up at night. Next, drivers (and passengers) who are less likely to buckle up in general may be more likely to be on the road at night. This study lends support to the first premise, since comparable groups (defined by men-women, vehicle type, roadway type, and urban-rural) showed comparably lower nighttime belt use rates. However, this study can't rule out the possible effects of other factors, such as age, race, education, and income, in producing the observed daytime/nighttime belt use difference. Because these additional factors were not measured, it isn't possible to definitively determine whether the observed differences were due to a reduced tendency to buckle up of the same people at night, or to less-likely-to-buckle people on the roads at night, or to some combination.

Regardless, nationwide traffic fatality rates are highest at night; the hours of 10 p.m. until 3:59 a.m. account for 25 percent of traffic fatalities (FARS 1998 – 2003), with only a relatively small percentage of traffic volume (about 12-15%, according to Hallenbeck et al., 1997).  These results suggest that this effect can be due in part to the lower belt use across all subcategories of occupants at night. 

Grant-funded enforcement programs to increase seat belt usage are conducted almost exclusively during daytime hours.  Selective Traffic Enforcement Programs like Click It or Ticket can rapidly improve belt usage.  Fully implemented CIOT programs result in immediate, short-term improvements in belt usage, and nearly all States in the Nation use CIOT as a means of improving their statewide belt use rates.  CIOT programs should use data such as that presented here to help plan and direct efforts toward times and locations most in need of improvement.  Tracking belt usage at all hours of the day and night and focusing programs where they are needed most should lead to further decreases in injuries and fatalities.