Study on the influence of sun glare on driving safety

Sun glare affects the drivers' vision of the road traffic environment ahead, thereby introducing risks to driving safety. The angle between the sun's position and the driver's line of sight is one of the essential factors that affects the driver's perception of sun glare. Based on an analysis of the formation mechanism of sun glare, this paper proposes a subjective visual recognition scale and test method for sun glare. According to subjective experience, sun glare can be divided into disability, disturbing, and acceptable glare. Through the outdoor visual recognition test, the vertical and horizontal visual recognition angle of 24 drivers were recorded from June 1, 2019 to December 31, 2019 when the driver's glare perception was in the critical state between disturbing glare and acceptable glare on sunny days. The results revealed that as the winter solstice approached, the maximum vertical visual recognition angle decreased in the critical state between disturbing glare and acceptable glare. However, the minimum vertical visual recognition angle tended to increase. In the same month, with the increase in the vertical visual recognition angle, the horizontal visual recognition angle in the critical state between disturbing glare and acceptable glare gradually decreased. Based on the most unfavourable principle of driving vision, the angular range of sun glare that affects driving safety was identified, and it constituted a vertical visual recognition angle of.. [5.6., 29.0.] and horizontal visual recognition angle of f. [ 57.7., 57.7.]. The results can provide a reference for road alignment selection and the development of anti-glare measures.