패턴분석을 이용한 도시고속도로 가변속도제어 운영에 관한 연구

Abstract

An expressway is an important roadway to relieve congestion of traffic, serve the mobility, and transport the freight in urban area, but the traffic flow in the expressway has been becoming worse due to not only unbalanced demand and supply but also inadequate control of the traffic flow on entrances and trunk road sections. In cases of European countries, however, the provision of detour information based on traffic information and various control methods referring the traffic flow has been developed and operated, resulting smooth service provisions by controlling the free flow. With these contexts, this paper tries to verify the proposed method of controlling traffic flow on the truck road sections of Seoul Naebu Expressway. To implement the variable speed control, a smoothing method under study was first conducted based on the adjusted data from vehicle detectors on the target roadway. Second, a pattern analysis enables us to discriminate four types of daily traffic situation of the Seoul Naebu Expressway and to compute its centralized value which used as a criterion for dividing the level of the variable speed control. Specifically, to apply the variable speed control we set up a transferable traffic volume, an average density, and an average speed as standard factors to determine the situation of the segmented roadway. Based on the proposed model and scenario, the analysis result reveals that traffic safety and efficiency can be improved by means of controlling speed of traffic flow on the trunk road sections. Additionally, we calculated an effective application time and the degree of reduction of the variable speed control according to the inflowing traffic volume. In case of speed reduction of -5km/h and -10km/h, the maximum inflowing traffic volume was 4800veh/h and 6000veh/h, and the effective application time was 40 and 30 minutes, respectively. As well as in case of large variance of the traffic flow, the influence of the speed reduction was mild. However, when imposing the speed reduction with -10km/h this paper shows a good result in terms of efficiency, showing that passing traffic was high and variance of speed was constant in spite of low average speed and a bit high average density. The proposed method under study, i.e., operating method of the variable speed control, is useful to control the traffic flow on the trunk road sections to FTMS managers in Korea. However, it is still limitation that the application range of the findings under study wouldn’t be applicable to other sites without verifying because newly estimated in this paper values have conformed based on only daily traffic flow of the Seoul Naebu expressway. In addition, the data used in the pattern analysis has accumulated by multi-years without various conditions and situations, which would cause the reduction of its transferability.