This study reports an analytical investigation on the development of SB4-grade separated concrete median barriers. The proposed barrier sections comprise three designs, with heights of 810, 1000, and 1270 mm and upper widths of 90, 120, and 120 mm, respectively. Before conducting collision analyses on the proposed sections, the considered collision analysis model was validated using real collision test results; the model was found to accurately predict the real collision test results. The proposed cross-sections were modeled to perform collision analysis according to SB4-grade collision conditions. Results indicated that increasing the cross-section height increased the damaged area and decreased the strength, while the occupant protection performance remained mostly unaffected. Furthermore, the proposed cross-sections met the strength and occupant protection performance criteria specified in domestic guidelines, suggesting their suitability as a separated concrete median barrier for bridges.

PURPOSES: This study analyzes feasibility for application white pavement markings in the roadways with median barrier. METHODS : By reviewing numerous relevant laws, standards, and operational cases, the white pavement markings' excellence was demonstrated. Driver’s behavior was analyzed through a virtual driving experiment using driving simulator and field tests. RESULTS: First, white pavement markings are superior to yellow pavement markings in terms of visibility, economics, and safety. Second, as a result of virtual driving experiment, the color of line in the roadway with median barrier didn’t affect the driver’s behavior such as the average vehicle speed, the distance bias in the lane and the separation distance from the centerline. Third, field test demonstrated that the driver tended to recognize the median barrier as an obstacle. In addition, the central driving ratio in the lane was increased due to improving the visibility of line at night in case of the white pavement markings. CONCLUSIONS : The application of white pavement markings in the roadways with median barrier can enhance traffic safety by improving the visibility of line at night.

The Golden Gate Bridge, known as one of the most beautiful bridges in the world, serves 110,000 vehicles per day, connecting San Francisco to inland as a segment of Highway 101 in California. The average peak hour volume over 6,500 vehicles per hour exceeds the traffic capacity of three lanes on each direction. Due to unique function of the bridge as a gateway of San Francisco, the peak directions in the morning and afternoon were explicitly distinguished. Recurrent traffic delay on the peak direction deteriorated level of service during the commute periods and caused user’s inconvenience and traffic accidents. The workers previously used to move plastic delineators to change lane configuration (4-2, 3-3, and 2-4) in several times a day. Neither did it provide prevention nor physical protection from the head-on collision on the bridge section. In January 2015, the Golden Gate Bridge was completely closed for two days to install the moveable median barrier (MMB) system, Road Zipper®, for more effective and safer variable lane management than the previous operation. One-meter section with 30.48 cm wide of highly reinforced concrete barriers are linked to form a continuous barrier wall and the machine lifts and passes the barriers through a conveyor system at a seeds up to 16 km/h. The MMB enables to quickly reverse lane configuration without traffic closure, providing more lanes to the peak direction as well as eliminating head-on collision on the bridge deck by presence of a physical structure. The traffic monitoring study result shows the significant improvement of average speed during peak hours and the regional traffic accident records shows improvement of safety after implementing the MMB on the Golden Gate Bridge. According to the traffic accident records, 13 injuries occurred in five accidents of vehicle collision in two-directions from 2007 to 2014 but no two-way accident has been reported since the operation of the Road Zipper® began. Furthermore, the MMB would be effectively implemented on construction work zones, managed lanes, variable lane management and other traffic operation to improve traffic safety and maximize utilization of roadway facilities.

국내 고속도로 콘크리트 중앙분리대는 SB5-B(270kJ)의 충돌등급에 저항하도록 설계되어 있다. 그러나 최근 대형 화물차 량의 충돌사고가 지속적으로 증가하는 경향을 보이고 있어 SB6(420kJ) 등급으로의 상향이 필요하다. 충돌등급 상향을 위한 새로운 중앙분리대 단면을 제시하기 위해서는 실제 충돌시험을 수행하여 기준 통과여부를 결정하며, 충돌시험 수행을 위한 적정 단면을 제시하기 위해서는 충돌해석을 통해 선정한다. 이러한 충돌해석의 정확도 향상을 위해서는 차량 모델, 콘크리트 단면 열화상태, 콘크리트 피복 두께 등 다양한 변수에 대한 정확한 변수 선정이 필요하다. 따라서 본 연구에서는 공차 중량, 단면 열화, 콘크리트 피복 두께에 대한 변수연구를 수행하여 충돌저항성능 저감을 확인하였다. 전체 중량뿐만 아닌 공차 중 량에 따라 중앙분리대의 충돌저항성능에 차이가 있는 것으로 확인되었으며, 10cm 이하의 콘크리트 피복 두께에서는 충돌저 항성능이 민감하게 증가 또는 감소한다. 단면 열화가 발생할 경우 중앙분리대의 충돌저항성능의 감소가 발생하여 열화정도 에 따른 보수 및 보강이 이루어져야 하는 것으로 판단된다. 따라서 콘크리트 구조물과 차량의 충돌해석을 수행할 경우 트럭 의 공차중량 비율, 콘크리트의 피복두께 및 열화에 대한 영향이 상세하게 고려될 필요가 있음을 확인하였다.

PURPOSES: By conducting the landscape survey that considered landscape factors of the Guide Coating in the Median Barrier that applied of the various level by simulating of the Guide Coating in the Median Barrier on the expressway, they showed the quantitative standard of landscape preference factors that the Guide Coating gives. METHODS: The shape of the Structural Equation Modeling used AMOS program and made a shape that is made of landscape preference for the Guide Coating in the Median Barrier on the expressway a dependent variable. RESULTS: Result in this, they showed that functionality and emotionalism are the factors that affect the landscape preference. CONCLUSIONS: In the main study, not only showing the Guide Coating in the Median Barrier on the expressway landscape valuation but also embodying the Structural Equation Modeling(SEM) of each group, knowing the Guide Coating and unknowing the Guide Coating. By embodying this, they could study that the drivers' quantitative standard is different when the Guide Coating become first applied and being changed after.

The second impact from the edge of cargo was found to be an crucial event causing large volume loss of concrete median barrier. Therefore, in order to improve local impact resistance of concrete median barrier during second impact, local model was developed and evaluations were conducted. Developed concrete median barrier showed the 125 kJ impact level based on conducted analysis.

This paper presents development of a high-performance concrete median barrier by means of device allowing deformation. A series of numerical analyses and full-scale crash tests were was conducted to develop optimized section of SB6 concrete median barrier The suggested section of SB6 concrete median barrier satisfies all requirements specified by MOLIT(Ministry of Land, Infrastructure and Transport)

Recently, overlay concrete median barrier in South Korea was newly developed. Accordingly, numerical analysis for occupant-protection performance was conducted before experimental test. In this study, dynamic analysis of vehicle-overlay concrete median barrier collision was conducted to confirm safety of driver. Furthermore, the analysis results of vehicle behavior was compared to experimental test.

This paper presents development of an optimized cross section of high performance concrete median barrier(SB6). A series of numerical analyses and full-scale crash tests were was conducted to develop optimized section of SB6 concrete median barrier The suggested section of SB6 concrete median barrier satisfies all requirements provided by MOLIT(Ministry of Land, Infrastructure and Transport)

최근 사용 중인 중앙분리대의 성능 등급을 뛰어넘는 사고가 발생하고 있다. 그러므로 피해를 줄이기 위해 중앙분리대의 성능 등급 을 현재의 SB5-B등급보다 상향된 기준에 맞춰 개선하는 것이 필요하다. 이에 본 연구에서는 중앙분리대 충돌시험결과를 활용하여 적절한 모델을 개발 및 검증하고 강도성능이 향상된 콘크리트 중앙분리대 개발을 목표로 하였다. 중앙분리대 성능은 SB6등급으로 목표성능등급을 설정 하였고, 중앙분리대의 강도성능 개선 요소로 강성보강과 연성보강의 두 가지 형태를 고려하였다. 강성보강으로는 와이어 메쉬 직경 증가, 중앙 분리대 상단 부위 철판보강을 고려하였고, 연성보강을 위해서는 중앙분리대 하단에 고무패드를 설치하여 성능향상을 컴퓨터 시뮬레이션을 통 해서 확인하였다. 시뮬레이션 결과, 와이어 메쉬 직경이 증가할 수록 중앙분리대의 부피 손실은 감소하였으며, 고무패드 사용시 트럭의 충격에 너지를 중앙분리대의 변형에너지로 전환하여 충격흡수에 효과적인 것으로 나타났다.

The map crack occurred in the concrete barrier and this crack is caused by the Alkali—Silica Reaction. As a result of the collision analysis according to the damage of the barrier, the barrier was found to be below the reference of structural performance when the crack height was 50cm or more. In the case, improvement is considered necessary.

In this study, collision analysis of overlay concrete median barrier under truck load was conducted depending on location of rebar and shear key. Obtained results indicates that the impact resistances of overlay concrete median barrier was improved as the rebar and shear keys are more closed to the top surface of the CMB.

Recently, the velocity of vehicle in highway has been increased due to improved driving environment. Unfortunately, the impact resistance of present concrete median barrier is not enough for increased impact severity due to increased velocity, furthermore, these increased velocity occurs another secondary accidents due to the concrete fragmentation. Therefore, in this study, the evaluation of impact resistance for developed concrete median barrier was performed with shock absorber.

In this study, we compared Korea and Foreign concrete median barrier(CMB)'s performance class and nominal impact severity from test standards. By using the literature study, minimum legal requirements of the CMB on expressway of Korea and Other countries were compared.

콘크리트 방호벽 및 중앙분리대는 교량의 부속시설이지만, 슬립폼 시공과 넓은 비표면적으로 인해 초기재령 균열이 발생하기 쉽다. 본연구에서는 대형 교량의 방호벽과 중앙분리대 콘크리트의 외관조사 및 비파괴실험을 수행하여 균열의 원인과 발생 균열의 패턴을 분석하였다. 이를 위해 시공기간을 고려하여, 건조수축, 수화열 해석이 수행되었으며, 현장의 환경조건을 고려하여 소성수축 특성을 평가하였다. 평가결과 대상구조물의 균열 원인은 철근위치에 따른 소성침하균열, 소성수축 및 건조수축에 의한 복부균열, 재료분리에 따른 상부균열로 추정할 수 있었다. 또한 균열원인과 발생 패턴을 도식화하였으며, 시공 및 재료분야에서 균열제어대책을 제안하였다. 해상위 교량에 설치하는 중앙분리대 및 방호벽 콘크리트는 환경조건 (풍속, 온도, 습도)에 매우 민감하여 초기재령균열이 쉽게 발생하므로 재료선택 및 시공방법에신중을 기해야 한다.