PURPOSES : Visibility of lanes on the road improves as retro-reflectivity rises. This helps reduce traffic accidents at nighttime or in bad weather. This study aimed to evaluate the effects of improved visibility on reduction of traffic accidents when the color of the lane in the median of the highway was changed from yellow to white. METHODS: In order to evaluate the accident reduction effect of the white left shoulder line, Hauer (1997)'s Comparison-Group method was chosen as an analysis methodology. The JungBu-2 highway, which is equipped with the white left shoulder line and is in trial operation, was chosen as a target for analysis. Data of accidents for 10 months before and after installation was collected and analyzed. In addition to the number of accidents, the types of accidents were classified into nighttime accidents, accidents in bad weather, and median collisions. The accident reduction effect of improved visibility of lanes was analyzed. RESULTS : The analysis’finding showed that installation of the white left shoulder line decreased the number of accidents by 28%. Moreover, improvement in visibility was effective in reducing nighttime accidents by 67.63%, accidents in bad weather by 55.19%, and median collisions by 48.55%. CONCLUSIONS: Based on the analysis’results in this study, it was concluded that white left shoulder line on the freeway contributed to reduce traffic accidents, especially nighttime accidents, accidents in bad weather, and median collisions.

PURPOSES : This research is to evaluate the effects of zig-zag marking. METHODS : Based on the literature review, This research adopt Comparison Group method which was developed by Hauer. RESULTS : The findings are as follows. Effectiveness of treatment at all site 1.06, intersection 0.92, median bus lane 1.93, school zone 0.50, below 6-lane 0.48, above 6-lane 1.19, cat vs person 0.57, car vs car 1.36, car only 1.29. CONCLUSIONS : Though the analysis, it was founded that zig-zag marking on the small scale road(below 6-lane) and school zone contribute to reduce traffic accidents(effectiveness of the treatment : 0.50, 0.48). But the accidents at large scale road and median bus lane where installed zig-zag marking demonstrated negative result.(effectiveness of the treatment indicates exceed 1.0).

터널, 교량, 커브구간 등 교통사고위험이 연속적으로 존재하는 도로구간에서의 대형교통사고를 예방하기 위하여 경찰청은 2007년 1월 위험도로구간에서 교통관리 대책의 일환으로서 무인구간속도위반단속시스템 시범설치 운영을 결정하였다. 2007년 12월 영동고속도로 둔내터널 강릉방면을 시작으로 2011년 7월 현재까지 고속도로 8개 구간 및 국도 3개 구간, 총 11개 구간 85km에서 무인구간속도위반단속시스템이 운영 중에 있다. 하지만 이러한 무인구간단속시스템의 설치가 교통사고 감소에 얼마나 기여하는지에 대한 실질적인 연구가 부족하였다. 따라서 본 연구에서는 고속도로를 중심으로 무인구간속도위반단속시 스템 설치 전 후 교통사고건수를 체계적으로 비교할 수 있는 비교그룹방법을 이용하여 무인구간속도위반단속시스템의 설치효과를 분석하고자 한다. 이를 위하여 2008년 고속도로에 설치된 무인구간속도위반단속시스템을 대상으로 설치 전 후 각 1년의 사고이력자료를 수집하여 분석하였다. 그 결과, 무인구간속도위반단속시스템을 설치하지 않았을 경우에 비해 사업을 시행함으로서 49.97% 사고감소효과가 있는 것으로 나타났다.