In Korea, a vehicle overtaking is prohibited by the law in tunnel and bridge sections where a road section has lanes with solid line. However, this regulation has some problems in terms of traffic operation and safety. So, it is necessary to find a way to improve the lane operation in tunnel and bridge sections. The objective of this research is to propose a systematical logic and specific standards to draw up an improvement of lane operation in tunnel and bridge sections on expressways. For that purpose, the status of lane operation in tunnel and bridge sections on both of the domestic and the abroad expressways and the improvement effect of the lane management were analyzed and, followed by it, the ways to improve lane management were suggested. In the comparison of the number of traffic accidents between road sections and tunnel sections, it was resulted that the number of traffic accidents per unit length (1km) of tunnel sections was lower than that of road sections. In addition, in the comparison of the fatality of traffic accidents, the fatality of tunnel sections on expressways was lower than that of other road tunnel sections. Through the analysis, it was resulted that there was a low correlation between the permission of the lane change in tunnel sections and the increase of traffic accidents. Moreover, in the comparing the traffic accidents between expressway tunnels and other road tunnels as well as between road sections and tunnel sections on expressways, there was no significant difference in safety between the solid line sections and the dotted sections. As a result of the analysis on the pilot operation section, it was expected that there would be no serious problems even if the permission of the lane change in tunnel and bridge sections was implemented, because the difference between in the existing solid-line sections and the pilot dotted line sections in terms of the lane change rate, the traffic characteristic, and the traffic accidents is not significant. Therefore, it needs to improve the current solid-line lane operation forbidding the lane change in tunnel and bridge sections. It is necessary to allow the lane change in tunnel and bridge sections with an appropriate level of facility conditions. In the long run, as in the cases of foreign countries, it is require to establish a principle to permit the lane change in tunnel and bridge sections. However, if necessary, it is need to consider the prohibition of the lane change in some tunnel sections by the engineering judgment. Allowing the lane change of the car in tunnel sections is not only merely a change of the lane operating method but also it is expected to be an important opportunity to increase the adherence of the driver to the laws and regulations and to change the drive culture by introducing a consistent traffic regulation.

In recent, a lot of fatal crashes with serious damage in terms of fatality and cost have been occurred in tunnel areas of expressways, drawing a huge social concern. However, each countermeasure for the tunnels in which traffic accidents have been happened is different, and it doesn’t seem that it is a fundamental measure because there is no unified standard. This research aims the application of standardized and comprehensive countermeasures for the improvement of traffic flow condition and safety in tunnel areas, through the cooperation with the organizations which are in charge of traffic safety management in Tunnel areas on expressways. The main components are as follows; the first, the establishment of comprehensive countermeasures providing tunnel areas with more safe traveling environment, the second, the standardization of comprehensive countermeasures, the third, the cooperation with the organizations in charging of traffic safety for the establishment of a detailed plan.

The objective of this study is to find a way to enhance winter traffic safety. This study has four main contents as follows. Firstly, the characteristic of winter traffic during the snowfall was examined in terms of traffic capacity, travel speed and standard deviation of travel speed. Next, the winter culture including prerequisites for driving and driving skills as well as the standard for snow removal were reviewed. Then, the cases of traffic management in UK, Germany and Japan were reviewed. Finally, the countermeasures to enhance the traffic safety were examined. After that, the variable sectional enforcement for speeding was proposed as a countermeasure to enhance traffic safety by reducing severe travel speed variation. The criteria for the operation of the variable sectional enforcement for speeding were set from 20% to 50% reduction of speed, depending on the amount of snowfall. The sections in which the accidents happened often during the snowfall were considered as the locations to implement the variable sectional enforcement for speeding.