ABSTRACT PURPOSES: It is desirable for buses to be parallel to the face of the bus shelter at a bus stop. In this way, passengers can safely use the buses without moving into the vehicle area. The study was a review of the current bus bay geometric guidelines, to determine whether they lead buses to stop parallel to the face of the bus shelter by analyzing vehicle trajectory. METHODS : A commercial software program for vehicle trajectory analysis was used under our assumptions about bus dimensions and geometric values. The final position of the bus was analyzed for multiple trajectory simulations, reflecting various geometric alternatives. RESULTS: Within the scope of the study, we concluded that the current design guidelines need to be revised by the design values suggested by the study. CONCLUSIONS : The results of the study suggested alternative design values for bus bay geometry, based on the assumption that buses should be parallel to the face of the bus shelter in order to prevent passengers from moving into the vehicle area.

PURPOSES : Before-and-after studies of red light cameras were conducted with the aim of reducing the number of side right-angle collisions. Three different methods were used for the before-and-after studies, and the analysis results were compared. METHODS: This research used the naive before-and-after method, the comparison-group method, and the empirical Bayes method to study the effects of red light cameras on side-angle collisions. The results of the three before-and-after methods were compared and interpreted in terms of safety indications at signalized intersections. RESULTS: The research results showed that side right-angle collisions can be reduced by installing red light cameras at signalized intersections. All three methods guarantee safety improvements of 25~30% on average. With regard to the results of each method, the naive before-and-after method, the comparison-group method, and the empirical Bayes method showed safety improvements of 25.6%, 27.8%, and 29.7%, respectively. CONCLUSIONS: It was concluded that red light cameras are an effective countermeasure to improve intersection safety. In particular, by installing red light cameras, side right-angle collisions can be reduced by up to approximately 25~30%.

PURPOSES: Safety consciousness can be the first factor to hinder the acceptance of design alternative, which moderates the applied design criteria in order to adapt the road to the natural terrain condition. METHODS : The method which enables to check the safety of design alternative by using design consistency concept is suggested. The method is based on the linked or interactive analysis between terrain and road alignment. Real design example is considered as a guide how to apply the method and the analysis result is discussed with the future research. RESULTS: Suggested method can be used for designers as a tool to review their design outputs can be safe as much as the original design. So, designers have the more objective judgement on their designs and have the confidence on their designs. CONCLUSIONS : The method is expected to be used as a tool to see the safety consciousness in an objective view, so any possible conflicts between designers and design-related personnels caused by the terrain-oriented design can be solved.

PURPOSES: Ambiguous decision on whether rural or urban area for road design can increase the construction cost and restrict the land use of surrounding area. However, administrative classification on rural and urban area is not directly related to road design because of this classification is not based on the engineering viewpoint, so method which can explain the road design context is required. METHODS: Method which enables to identify the area for road design is suggested based on the deceleration expected to be experienced by drivers who use the road section concerned. Deceleration rate corresponding to the area such as rural or urban suggested in Road Design Guideline is used as the criteria to identify the area by comparing this value with the estimated deceleration rate at the road section concerned. Speed profile method is utilized to derive the deceleration rate, and speed estimation way for reflecting both road geometry and intersection is suggested using stopping sight distance concept. RESULTS: The procedure of the method application is suggested, and the design example utilizing the method is provided. CONCLUSIONS : The method is expected to be used to identify the area for road design with engineering viewpoint, and design consistency among the roads with similar driving environment can be made.

PURPOSES : The lack of details of design guideline for zig-zag shaped section approaching central bus stop leads an traffic accident proneness. So, this study analysed the geometric elements of central bus stop area in terms of vehicle dynamics and suggested design alternatives. METHODS: The study analysed a dynamic behaviour of bus moving in and out of zig-zag shaped section using Auto-Turn under scenarios. Based upon dynamic analysis, the study found out the width of overtaking lane is the most influential factor for a safe moving at zig-zag alignment. RESULTS : The width of overtaking lane at design speed of 40, 50, and 60 km/h respectively was suggested given taper ratio of 1 to 10 required for Bus Rapid Transit (BRT), and the lane width is not wider than 4.0m which possibly makes two vehicles using the same lane. Also, the width of overtaking lane which mitigates the taper ratio was suggested with the same restriction about the maximum lane width. CONCLUSIONS: The results of the study can be used to prepare a design guideline on zig-zag shaped alignment of central bus exclusive lanes. The more stable moving is expected by applying the design alternatives suggested, therefore the lower rate of traffic crashes at the vicinity of central bus stops.

PURPOSES: This study aimed to measure the skid resistance of the sidewalk in order to find out the relationship between different surface types and skid resistance. By using British Pendulum Tester, skid resistance of sidewalk was measured in a wet after snow-melt, sludgy, and snowy conditions. METHODS : The skid resistance was measured on surfaces including Concrete Interlocking Block Paving, Colour Asphalt Pavement, Granite Block Paving, Manhole, and Tactile Paving for Visually Impaired. Five trials at each measurement were made, and the average and standard deviation were derived. RESULTS: The skid resistance measured in wet after snow-melt, sludgy, and snowy conditions for the various surface types are summarized and compared. Reduction rates of skid resistance of sludgy and snowy against wet after snow-melt are also analysed. The skid resistance variation between measurement points which mimic pedestrian route in study site are analysed to check out the consistency of the skid resistance along the sidewalk. CONCLUSIONS : The study concluded that the skid resistance of sidewalk surfaces varied depending on the surface types and weather conditions. Secondly, reduction rates of skid resistance according to weather changes are varied depending on the surface types, Thirdly, consistency of skid resistance along the pedestrian route is hardly acquired in the study site at least. So, future study on the consistency evaluation for skid resistance along sidewalk is strongly recommended.

PURPOSES : This study aims to suggest the optimal spacing between speed humps which is placed at traffic calming areas including pedestrian priority zones, school zones, and residential areas. METHODS: The study measured the operating speed of vehicles passing through two successive humps by using laser gun in 0.2 seconds interval, and analysed the basic statistical characteristics of speeds data to have an insight on the relationship between spacing and speed. Assumption was made to derive the maximum spacing within which two successive humps influence each other. RESULTS: The statistically significant model explaining the relationship between spacing and 85th percentile speed of vehicles was derived as well as the maximum spacing maintained in order to take the benefits of successive installation of humps. CONCLUSIONS: Spacing of 20 meters was suggested to achieve the widely accepted target speed of 30 km/h in traffic calming zone, and spacing of 70 meters was suggested as a maximum spacing. The comparison across the studies were made and empirical reasoning the difference of results between studies was discussed as well as the future studies.

PURPOSES : The lack of details of guidelines on how to install the Chicane for traffic calming leads the practical difference across the calming areas, so the benefits expected from these facilities are not hardly observed. In this context, this study analysed the relationship between the geometric design alternatives of Chicane with the dynamic behaviour of vehicles in terms of speed and trajectory. METHODS : The study analysed vehicle dynamic behaviour using dynamic analysis program Auto-Turn under various geometric conditions of Chicane. RESULTS : This study suggested the design alternatives of Chicane using terms such as "longitudinal displacement value", "lateral displacement value", etc. which are defined in the study. The suggested combination set is fulfilling the desired or target speed of vehicles and clearance between vehicle and roadside at the same time. CONCLUSIONS : The results from this study can be applied to install Chicane corresponding to the local condition where target speed is 30km/h. The study showed the design alternatives of chicane corresponding to the given road cross-sectional design and clearance to roadside for passenger cars and light truck respectively.

이 논문에서는 뒷채움이 부실한 묻힌기초 위에 세워진 건축물의 지반증폭계수에 대한 기초묻힘으로 인한 저감계수를 산정하기 위한 연구를 비선형 의사 3D 수평지진해석이 가능한 P3DASS 유한요소 프로그램으로 수행하였다. 지반은 30m 두께로 균질하고탄성과 점성이 있는 등방성 지반으로 단단한 암반 위에 놓인 것으로 가정하였고, 기초는 반경이 10-70m인 등가원형 강체기초로 기초묻힘은 0, 10, 20, 30m인 경우를 고려하였다. 지진해석은 노두에서 실측한 7개 지진기록의 유효지진가속도를 0.1g로 조정한 후 연약지반밑 암반에서의 지진기록을 생성하여 수행하였다. 연구 결과에 의하면, 매우 연약한 지반에 깊게 묻힌 뒷채움이 부실한 소형기초인 경우를제외하고는 지반증폭계수가 기초묻힘비가 깊어 질수록 점진적으로 감소하고 기초크기에 따른 편차는 크지 않은 것으로 평가되었다. 따라서 뒷채움이 부실한 묻힌기초의 지반증폭계수를 설계기준에 주어진 지표면기초의 지반증폭계수에 곱해서 구할 수 있는 표준저감계수를전단파속도와 지반종류에 따라 제안하였다. 이 표준저감계수는 지반의 평균전단파속도에 따라 보간하여 사용할 수도 있다.

일본 고베지진후 구조물 수직방향 내진거동의 중요성은 잘 인식되었으나 대부분의 내진설계규준에서는 지반조건을 규정하지 않아 수직방향 구조물 내진해석시 대개 토질과 기초조건을 무시하고 수행하였다 이 논문에서는 연약지반이 Taft 지진과 El Centro 지진의 수직방향 지진하중을 받는 구조물의 수직방향 반응에 미치는 영향을 알아보기 위해 기초크기, 기초 및 지반깊이 , 기초근입깊이 및 말뚝기초가 수직방향 내진반응스펙트럼에 미치는 영향에 대해 연구하였는데 지반은 UBC-97에서 분류한 Sa. Sc. SE를 기초크기는 중 대형 기초를. 기초 및 지반깊이는 30m 와 60m를 기초근입깊이를 0m와 15m를 고려하였으며 연약지반에 설치한 말뚝은 기성제 콘크리트 선단지지말뚝을 고려하였다 연구결과에 의하면 기초크기는 구조물의 수직방향 내진반응에 별 영향이 없지만 지반깊이는 수평방향 내진해석에서처럼 기초 및 60m까지 고려해야 하며 연약지반위에 설치된 묻힌기초와 얕은 말뚝기초는 구조물의 수직방향 내진거동을 크기 증폭시켰다.