횡풍에 의한 차량 사고 위험도 분석 및 방풍벽 설치기준에 관한 연구

Abstract

차량이 고속으로 주행할 때 진행방향의 직각으로 부는 강풍은 차량의 안전성을 저해하여 사고를 유발할 수 있다. 강풍에 의한 차량 사고는 사고로 인한 직접적인 손실, 도로시설물의 파손 및 추가 설치로 인한 직접 비용, 교통지체로 인한 물류비용 및 심리적인 영향으로 인한 간접적인 손실을 유발하게 된다. 또한 차량 사고로 악화되진 않더라도 바람으로 인한 잦은 요잉 현상은 운전자에게 심리적으로 불안감을 주어 도로 품질에 대한 신뢰감을 저하시킬 수 있다. 본 연구는 강풍 도로구간의 차량 주행 안전성을 확보하기 위한 목적으로 수행되었다. 우선 운전자의 특성을 고려한 경로이탈추정모델 활용하여 차량 거동 메커니즘을 분석하였다. 또한 자동차 동역학 시뮬레이션 프로그램을 활용하여 승용차, 화물차 및 승합차 등 총 13개 차종을 대상으로 사고 위험성이 가장 큰 상태의 위험풍속을 산정하였다. 도로 구간 중 강풍 위험 지역을 파악하기 위해 적합한 확률 분포를 선정하였으며 단기계측을 통한 현장장기풍속측정방법을 적용하여 신뢰도를 높였다. 강풍으로 인한 차량사고 관계를 주행위험풍속 초과확률, 사고 발생가능확률, 위험 비용 및 편익을 통해 정식화하였다. 그리고 방풍대책 필요성을 결정하기 위한 B/C분석기법을 제시하였다. 또한 연간 사고횟수분석을 통한 방풍벽 설치 필요성 결정기법도 제시하였다. 사고 위험도를 저감하기 위해 방풍벽을 설치하여 풍압을 감소시키게 된다. 본 연구에서는 국내 설치되는 방풍벽을 대상으로 풍동실험으로 방풍벽 배면의 풍속저감효과, 적정 설치 높이, 병렬 교량인 경우 이격거리별 설치 방법, 설계를 위한 풍압계수 등을 제시하였다. 방풍벽 설치가 어려운 지역에 대한 사고 위험도 저감 방안으로는 주행속도를 낮추는 방법을 고려할 수 있다. 기존 규정(안)과 주행 안전성 분석 결과를 토대로 실무에서 적용할 수 있는 풍속 크기별 제한속도를 제시하였다. 결론적으로 본 연구를 통해 횡풍을 받는 차량의 안전성을 정량적으로 파악할 수 있었으며, 사고 위험도를 고려한 방풍벽 필요성 결정기법으로 합리적으로 설치 지역을 선별할 수 있을 것이다. 또한 방풍벽 설치에 관한 기준과 제한속도 제시로 강풍 도로구간의 차량 사고를 저감하는데 도움이 될 것으로 판단된다.| Vehicles in coastal regions or in a valley area sometimes deviate from their desired path because of the strong crosswind accelerated by the concentration of the bridges or valleys. Continual compensation of the steering wheel against the crosswind causes stress for the driver. Also, the severe yawing may occur and it can lead to traffic accident. Although this kind of instability of driving vehicle has been reported, literatures related to criteria or action plan have not been much found yet. This study assesses the crosswind sensitivity of road vehicle. It investigates the design criteria required for wind barriers to protect vehicles running on an expressway under the strong crosswind. At the first stage of this study, the lateral deviations of vehicles in crosswind are computed from the commercial software, CarSim and TruckSim, and the critical wind speeds for driving safety are found to 35m/s for a small passenger car and truck, yet 20m/s for a bus. Also It assesses the effect of the weather conditions It presents a decision making process for installation of wind barrier. To determine whether it is needed to install wind barrier or not, cost and benefit from wind barrier are calculated during lifetime. In obtaining the traffic accident risk, probabilistic distribution of wind speed, daily traffic volume, mixture ratio in the volume, and duration time for wind speed range are considered. It is recommended to install wind barrier if benefit from the barrier installation exceed construction cost. In the numerical examples, case studies are shown for risk and benefit calculation and 75 risky bridges on Korean expressway are all evaluated to identify the number of installation sites. Also, it is recommended to install wind barrier if the annually traffic accidents occur above the predefined level at the region according to the road operation policy. It presents two methods to reduce the traffic accidents by the crosswind. Firstly, It recommends a few of criteria for wind barrier which is installed in order to reduce the wind pressure through the tests. From the wind tunnel tests, the minimum height of a wind barrier required to reduce the wind speed by 50% was found to be 1/8 times of the road width. In the case of parallel bridges, the placement of two edge wind barriers plus one wind barrier at center is recommended for a separation distance larger than 20m (four lanes) and 10m (six lanes) respectively, otherwise two wind barriers are recommended. Though there is little difference in material type and placing location, the design pressure coefficients used for wind barriers such as expanded metal and folded porous plate is recommended to 0.8. When the wind direction for a certain parallel bridge is consistent, one barrier is recommended to be added in front of the leeward side of the bridge. If it is disadvantage to install the wind barrier, it is needed to reduce the vehicle speed in order to assure the safe travelling. And this study presents the limit speed of road vehicles according to the wind speed.; Vehicles in coastal regions or in a valley area sometimes deviate from their desired path because of the strong crosswind accelerated by the concentration of the bridges or valleys. Continual compensation of the steering wheel against the crosswind causes stress for the driver. Also, the severe yawing may occur and it can lead to traffic accident. Although this kind of instability of driving vehicle has been reported, literatures related to criteria or action plan have not been much found yet. This study assesses the crosswind sensitivity of road vehicle. It investigates the design criteria required for wind barriers to protect vehicles running on an expressway under the strong crosswind. At the first stage of this study, the lateral deviations of vehicles in crosswind are computed from the commercial software, CarSim and TruckSim, and the critical wind speeds for driving safety are found to 35m/s for a small passenger car and truck, yet 20m/s for a bus. Also It assesses the effect of the weather conditions It presents a decision making process for installation of wind barrier. To determine whether it is needed to install wind barrier or not, cost and benefit from wind barrier are calculated during lifetime. In obtaining the traffic accident risk, probabilistic distribution of wind speed, daily traffic volume, mixture ratio in the volume, and duration time for wind speed range are considered. It is recommended to install wind barrier if benefit from the barrier installation exceed construction cost. In the numerical examples, case studies are shown for risk and benefit calculation and 75 risky bridges on Korean expressway are all evaluated to identify the number of installation sites. Also, it is recommended to install wind barrier if the annually traffic accidents occur above the predefined level at the region according to the road operation policy. It presents two methods to reduce the traffic accidents by the crosswind. Firstly, It recommends a few of criteria for wind barrier which is installed in order to reduce the wind pressure through the tests. From the wind tunnel tests, the minimum height of a wind barrier required to reduce the wind speed by 50% was found to be 1/8 times of the road width. In the case of parallel bridges, the placement of two edge wind barriers plus one wind barrier at center is recommended for a separation distance larger than 20m (four lanes) and 10m (six lanes) respectively, otherwise two wind barriers are recommended. Though there is little difference in material type and placing location, the design pressure coefficients used for wind barriers such as expanded metal and folded porous plate is recommended to 0.8. When the wind direction for a certain parallel bridge is consistent, one barrier is recommended to be added in front of the leeward side of the bridge. If it is disadvantage to install the wind barrier, it is needed to reduce the vehicle speed in order to assure the safe travelling. And this study presents the limit speed of road vehicles according to the wind speed.