High beam headlamp use rates: Effects of rurality, proximity of other traffic, and roadway curvature

  • Published: Traffic Injury Prevention 18(7): 2016: 716-723
  • Authors: Reagan, I.J., Brumbelow, M.L., Flannagan, M.J. & Sullivan, J.M.
  • Date Added: 08 Mar 2018
  • Last Update: 08 Mar 2018
  • Format: pdf


The study examined factors associated with the rate of high beam use of isolated vehicles on a variety of roadways in the Ann Arbor, Michigan area.


Twenty observation sites were categorized as urban, rural, or on a rural/urban boundary and selected to estimate the effects of street lighting, road curvature, and direction of travel relative to the city on high beam use. Sites were selected in pairs so that a majority of traffic passing one site also passed through the other.

Measurement of high beams relied on video data recorded for 2 nights at each site, and the video data also were used to derive a precise measure of the proximity of other traffic.

Nearly 3,200 isolated vehicles (10 s or longer from other vehicles) were observed, representing 1,500-plus vehicle pairs.

Key Findings:

  • Across the sample, 18% of the vehicles used high beams. Seventy-three percent of the 1,500-plus vehicle pairs used low beams at each paired site, whereas 9% used high beams at both sites.

  • Vehicles at rural sites and sites at the boundaries of Ann Arbor were more likely to use high beams than vehicles at urban sites, but use in rural areas compared with rural/urban boundary areas did not vary significantly.

  • Rates at all sites were much lower than expected, ranging from 0.9 to 52.9%. High beam use generally increased with greater time between subject vehicles and leading vehicles and vehicles in the opposing lane.

  • There were mixed findings associated with street lighting, road curvature, and direction of travel relative to the city.


  • Maximizing visibility available to drivers from headlights includes addressing the substantial underuse of high beam headlamps. Advanced technologies such as high beam assist, which switches automatically between high and low beam headlamps depending on the presence of other traffic, can help to address this problem.


Night time driving; Visibility; High beam headlamps; High beam assist; Adaptive driving beam