PURPOSES : The "Super-Bus Rapid Transit" (S-BRT) standard guidelines recommend installing physical facilities to separate bus lanes, so as to remove possible conflicts with other traffic when using an existing road as an S-BRT route. Based on a collision simulation, we reviewed the protective performance and installation method of a low-profile barrier, i.e., one that does not occupy much of the width of the road as a physical facility and does not obstruct the driver's vision. METHODS : The LS-DYNA collision analysis software was used to model the low-profile barrier, and a small car collision simulation was performed with two different installation methods and by changing the collision speeds of the vehicle. The installation methods were divided into a fixed installation method based on on-site construction and a precast method, and collision speeds of 80 and 100 km/h were applied. The weight of the crash vehicle was 1.3 tons, and the segment lengths of the low-profile barriers were 2.5 and 4.0 m, respectively. The lowprofile barriers were modeled as precast concrete blocks, and the collision simulation for a fixed concrete barrier was performed by fixing the nodes at the bottom of the low-profile barrier. The low-profile barrier comprised a square cross-section reinforced concrete structure, and the segments were connected by connecting steel pipes with varying diameters to wire ropes. RESULTS : From comparing and analyzing the small car collision simulations for the changes in collision speeds and installation methods of the low-profile barrier, a significant difference was found in the theoretical head impact velocity (THIV) and acceleration severity index(ASI) for the 2.5-m barrier at a collision speed of 80 km/h. However, the differences in the installation method were not significant for the 4.0-m barrier. The occupant safety index with a collision speed of 80 km/h was calculated to be below the limit regardless of the installation method, and the length of the segment satisfied the occupant protection performance. At a collision speed of 100 km/h, when the segment length of the 2.5-m barrier was fixed, the THIV value exceeded the limit value; thus, the occupant protection performance was not satisfied, and the occupant safety index differed depending on the installation method. The maximum rotation angle of the vehicle, which reflects the behavior of the vehicle after the collision, also varied depending on the installation method, and was generally small in the case of precast concrete. CONCLUSIONS : Low-profile barriers can be installed using a fixed or precast method, but as a result of the simulation, the precast movable barrier shows better results in terms of passenger safety. Therefore, it would be advantageous to secure protection performance by installing a low-profile barrier with the precast method for increased safety in high-speed vehicle collisions.

PURPOSES : This study was conducted to analyze the driving width of the vehicle body and off-track width of front-rear tires when a large vehicle or an articulated bus passes through a roundabout. METHODS : The driving width was measured using two methods considering the off-tracking tire and the size of the vehicle body. The test conditions of the roundabout were considered as follows: number of entry/exit sections (three-legs roundabout and four-legs roundabout), number of lanes (one lane and two lanes), driving speed (10 km/h, 20 km/h, and 30 km/h), driving trajectory (centerline and maneuver), and driving path (right turn, straight, left turn, and U-turn). The driving trajectories of large buses or articulated buses were analyzed using a road design simulation tool (AutoTURN Pro). RESULTS : Consequently, it was observed that the driving width calculated using the off-track width of the front and rear tires was lower than that analyzed for the vehicle body. The width was smaller in the case of driving in the one-lane roundabout than that in the two-lane roundabout. In particular, it was analyzed that the situation in which the turning path invades the lane appeared in left-turn (East → South) and U-turn (East → East) situations. The width was narrower in the case of driving in the one-lane roundabout than that in the two-lane roundabout. CONCLUSIONS : The study results are expected to be applied for designing roads when large buses or articulated buses are selected as design vehicles.

PURPOSES : The percentage of vehicle overturning accidents is 16.3% of vehicle alone fatal accidents, with a fatality rate of 9.0%, accounting for a high proportion, and heavy vehicles with a high center of gravity are vulnerable to overturning accidents. In the standard guidelines of Super-Bus Rapid Transit(S-BRT), it is recommended to install physical facilities that separate buses from other traffic on dedicated bus ways, and lane separation facilities are being developed. To develop low-profile lane separation facilities that do not interfere with sight obstruction for pedestrians and drivers, it is necessary to review the height of lane separation facilities to prevent overturning crashes of heavy vehicles. METHODS : Heavy vehicle impact conditions of 8ton-55km/h-15°, 8ton-55km/h-20°, 8ton-65km/h-15°, and 8ton-65km/h-20°were applied to compare the vehicle behavior by the height of lane separation facilities using LS-DYNA, a three-dimensional nonlinear impact analysis program based on speed and angle changes. In addition, the behavior of the vehicle after the collision was analyzed to examine the impact conditions in which an overturning crash occurs when a heavy vehicle collides with a low-profile lane separation facility and the appropriate height of the facility to prevent overturning. RESULTS : In general, under the 8ton-65km/h-15°condition, which is a heavy vehicle impact condition used in the performance standard of the barrier, the vehicle’s behavior after the collision was stable as the height of the lane separation facility increased. CONCLUSIONS : Therefore, when the impact conditions were 8ton-65km/h-15°or less, it was determined that the appropriate height to prevent the condition of the lane separation facility was 400mm or more.

PURPOSES : According to the guidelines of Super Bus Rapid Transit(BRT), dedicated bus roads and dedicated bus lanes shall be used, and physical lane separation facilities should be installed for lane separation. Therefore, physical barriers (lane separation facilities) are being developed for exclusive bus operations. Low-profile lane separation facilities should be developed that do not interfere with the views of pedestrians and drivers. The appropriate heights of the barrier to prevent overriding in the event of passenger car crashes were reviewed. METHODS : By applying the performance standards of the safety barrier, passenger protection performance according to the change in the height of the lane separation facilities and the vehicle behavior after the crash were analyzed using computer crash simulations. Crash criteria of 1.3 ton-60 km/h-20°and 1.3 ton-80 km/h-20°were used as vehicle impact conditions. The simulation was performed by increasing the height of the lane separation facilities from 200 mm to 500 mm. To prevent the deformation of the lane separation facilities owing to a vehicle crash, the boundary conditions of the node under the lane separation facilities were fixed and modeled. RESULTS : The collision simulation results showed that, for a collision speed of 60 km/h, no override occurred for the height of the lane separation facility of 250 mm or more, and for a collision speed of 80 km/h, no override occurred for the height of the lane separation facility of 300 mm or more. CONCLUSIONS : Therefore, the appropriate height of the lane separation facility for the collision of a passenger car with a collision speed of 80 km/h or less was determined to be 300 mm or more.

PURPOSES : In this study, we review the method and equations suggested in the usual guidelines to calculate the lane widening for curved sections, and proposed values of the widths and the amount of widening that reflected the driving trajectory of an articulated bus. METHODS : A simulation was used to obtain the trajectory of articulated bus, which is adequate for a Super-Bus Rapid Transit(S-BRT) service with the longest length of the design vehicle. This study was conducted by dividing the trajectory into curved and tangential sections, and the extent of widening was analyzed by changing the rotation angle by 5°. In addition, the results related to the amount of widening from the conducted analysis were applied to particular situation of right turns of an articulated bus at urban intersection. The possible conflict situations that may occur were analyzed. RESULTS : When analyzing the rotation angle at which the size of the driving width was set to be the largest for each lane center radius, the rotation angle for a lane center radius ( =15m) was 35°, the rotation angle for a lane center radius ( =20m) was 45°, the rotation angle for a lane center radius ( =25m) was 55°, and the rotation angle for a lane center radius ( =30m) was 60°. CONCLUSIONS : As the radius increases, the required driving width and the amount of widening decrease. The rotation angle that requires the largest driving width is presented. The results show that as the central radius ( ) of the lane increases, the amount of widening for each rotation angle decreases. In addition, based on the results of the analysis of the driving width for each rotation, the trajectory of an articulated bus was applied to an at-grade intersection to check the distance required for widening from the beginning point of the curve.

PURPOSES: The purpose of this study is to identify the key factors that influence a driver’s trust in road-freezing risk information METHODS : A survey was designed and conducted in the metropolitan area to analyze drivers’perception towards road-freezing risk information. A binary logistic regression model was developed based on the survey responses. The statistically significant model coefficients were determined and their odds ratios were calculated. Finally, they were considered as the key factors influencing drivers’trust in roadfreezing risk information. RESULTS : The developed binary logistic regression model was validated through statistical tests. The final results indicated that previous experiences of accidents on slippery roads, as well as route choice patterns are statistically significant, having 95% confidence levels. CONCLUSIONS : Previous experiences of accidents on slippery roads and road choice patterns are the factors that most significantly influence drivers’trust in road-freezing risk information. The findings of this study will be used as fundamental data in establishing tailored road-freezing risk mitigation procedures and services.

PURPOSES:This study suggests a specific methodology for the prediction of road surface temperature using vehicular ambient temperature sensors. In addition, four kind of models is developed based on machine learning algorithms.METHODS:Thermal Mapping System is employed to collect road surface and vehicular ambient temperature data on the defined survey route in 2015 and 2016 year, respectively. For modelling, all types of collected temperature data should be classified into response and predictor before applying a machine learning tool such as MATLAB. In this study, collected road surface temperature are considered as response while vehicular ambient temperatures defied as predictor. Through data learning using machine learning tool, models were developed and finally compared predicted and actual temperature based on average absolute error.RESULTS:According to comparison results, model enables to estimate actual road surface temperature variation pattern along the roads very well. Model III is slightly better than the rest of models in terms of estimation performance.CONCLUSIONS :When correlation between response and predictor is high, when plenty of historical data exists, and when a lot of predictors are available, estimation performance of would be much better.

OBJECTIVES : Fixed roadside objects are a threat to drivers when their vehicles deviate from the road. Therefore, such roadside objects need to be suitably dealt with to decrease accidents. This study determines the factors affecting the severity of accidents because of fixed roadside objects. METHODS : This study analyzed the crash severity impact of fixed roadside objects by using ordered probit regression as the analysis methodology. In this research, data from 896 traffic accidents reported in the last three years were used. These accidents consisted of sole-car accidents, fixed roadside object accidents, and lane-departure accidents on the national highway of Korea. The accident severity was classified as light injury, severe injury, and death. The factors relating to the road and the driver were collected as independent variables. RESULTS: The result of the analysis showed that the variables of the crash severity impact are the collision location (left side), gender of the driver (female), alcohol use, collision facility (roadside trees, traffic signals, telephone poles), and type of road (rural segments). Additionally, the collision location (left side), gender of the driver (female), alcohol use, collision facility (street trees, traffic signals, telephone poles), and type of road (rural segments), in order of influence, were found to be the factors affecting the crash severity in accidents due to fixed roadside objects. CONCLUSIONS: An alternative solution is urgently required to reduce the crash severity in accidents due to fixed roadside objects. Such a solution can consider the appropriate places to install breakaway devices and energy-absorbing systems.

PURPOSES: This study evaluates the reliability of the patterns of changes in the road surface temperature during winter using a statistical technique. In addition, a flexible road segmentation method is developed based on the collected road surface temperature data. METHODS: To collect and analyze the data, a thermal mapping system that could be attached to a survey vehicle along with various other sensors was employed. We first selected the test route based on the date and the weather and topographical conditions, since these factors affect the patterns of changes in the road surface temperature. Each route was surveyed a total of 10 times on a round-trip basis at the same times (5 AM to 6 AM). A correlation analysis was performed to identify whether the weather conditions reported for the survey dates were consistent with the actual conditions. In addition, we developed a method for dividing the road into sections based on the consecutive changes in the road surface temperature for use in future applications. Specifically, in this method, the road surface temperature data collected using the thermal mapping system was compared continuously with the average values for the various road sections, and the road was divided into sections based on the temperature. RESULTS : The results showed that the comparison of the reported and actual weather conditions and the standard deviation in the observed road surface temperatures could produce a good indicator of the reliability of the patterns of the changes in the road surface temperature. CONCLUSIONS: This research shows how road surface temperature data can be evaluated using a statistical technique. It also confirms that roads should be segmented based on the changes in the temperature and not using a uniform segmentation method.

기상 조건을 고려하여 교통사고 발생 원인과의 관계를 분석한 연구에서는 갑작스러운 온도 또는 기상 상 태의 변화는 교통사고에 영향을 준다는 결론을 제시하고 있다. 특히, 동절기에 기온이 떨어지는 경우, 도로 결빙에 의한 교통사고가 발생할 가능성이 높으며, 도로 표면에서 발생하는 결빙 현상은 운전자가 육안으로 쉽게 관측 할 수 없는 한계를 가진다. 따라서, 노면에 발생하는 결빙은 교통사고의 원인으로 작용 할 수 있 기 때문에, 결빙이 발생한 구간에서 운전자의 주의를 높여 줄 수 있는 대안 등이 요구된다. 결빙 현상은 야 간과 같이 온도가 낮아지는 시간에 발생하므로, 결빙을 예측하기 위해서는 노면 온도에 대한 정보가 필요하 다. 그러나, 노면온도 변화에 직･간접적으로 영향을 주는 대기 기상정보는 거시적(5km*5km 단위) 범위에 서 정보가 제공되므로, 운전자가 주행하는 도로망에 대한 정확한 정보를 제공하는데 어려움이 따른다. 따라 서, 본 연구에서는 운전자가 주행하는 도로망에 대기 온도를 제공 및 예측하기 위해 대기온도, 대기습도, 풍 향 등을 고려한 기상정보와 노면 온도 자료를 활용하여 노면 온도를 예측하는 모형을 개발하고자 한다. 노면 온도 예측 모형을 개발하기 위하여 Thermal Mapping 장비가 장착된 차량을 이용하였으며, Thermal Mapping 장비를 통해 노면온도, 대기온도, 대기습도를 측정한다. 또한, 시스템적으로 GPS가 연계되어 있어서, 정확한 위치 정보의 취득이 가능하며, 노면온도에 영향을 미치는 기상정보는 기상청에 서 수집하여 제공하는 온도, 습도, 풍속 등을 이용하였다. 또한, 지형의 요소를 교량부, 산지부, 평지부, 해안, 내륙을 구분하여 지형적인 요소도 반영 될 수 있도록 하였다. 예측 모형은 비선형 분석 모형을 사용 하여 노면 예측 정확도에 적합한 알고리즘을 사용할 계획이며, 본 연구의 결과는 기상과 관련된 교통안전 관련 연구에 활용될 것으로 기대한다.

PURPOSES: This study prioritizes potential technology for establishing a safe work zone environment on roadways. We consider almost all conceivable technologies that enable mitigation of unexpected accidents for both road workers and drivers. METHODS: This study suggests a methodology to set the priority of potential technology for establishing a safe work zone environment by using the analytical hierarchy process (AHP). For this purpose, the AHP structure was first developed. Thereafter, a web-based survey was conducted to collect experts’opinions. Based on the survey results, weights associated with the relevant criteria of the developed structure were estimated. With the consistency index (CI) and consistency ratio (CR), we verified the estimated weights. In addition, a sensitivity analysis was performed to confirm whether the estimated weights were reliable. We finally proposed the priority for potential technology for establishing a safe work zone environment on roadways. RESULTS: In the first level, safety technology has the highest priority, and real-time information delivery for work zone, hazard warning for drivers, and temporal automated operation for traffic facilities were selected in the second level of hierarchy. CONCLUSIONS : The results imply that establishing the priority will be useful to establish a future road map for improving the work environment for road workers and drivers by employing appropriate protection facilities and developing safety systems.

PURPOSES: The purpose of this study is to verify traffic accident injury severity factors for elderly drivers and the relative relationship of these factors. METHODS: To verify the complicated relationship among traffic accident injury severity factors, this study employed a structural equation model (SEM). To develop the SEM structure, only the severity of human injuries was considered; moreover, the observed variables were selected through confirmatory factor analysis (CFA). The number of fatalities, serious injuries, moderate injuries, and minor injuries were selected for observed variables of severity. For latent variables, the accident situation, environment, and vehicle and driver factors were respectively defined. Seven observed variables were selected among the latent variables. RESULTS: This study showed that the vehicle and driver factor was the most influential factor for accident severity among the latent factors. For the observed variable, the type of vehicle, type of accident, and status of day or night for each latent variable were the most relative observed variables for the accident severity factor. To verify the validity of the SEM, several model fitting methods, including , GFI, AGFI, CFI, and others, were applied, and the model produced meaningful results. CONCLUSIONS: Based on an analysis of results of traffic accident injury severity for elderly drivers, the vehicle and driver factor was the most influential one for injury severity. Therefore, education tailored to elderly drivers is needed to improve driving behavior of elderly driver.

PURPOSES : This study is to develop a automate road mapping system using ARASEO(Automated Road Analysis and Safety Evaluation TOol) for road management. METHODS: The road survey van named ARASEO(Automated Road Analysis and Safety Evaluation TOol) was used to generate highway drawings for Korea National Road number 37 automatically. In order to generate the highway drawings for purpose of road management, it is required to acquired the information for highway alignment, road width and road facilities such as safety barrier and road sign. Therefore the survey van acquired and analyzed the road width, median and guardrail data using rear side laser sensor of ARASEO and recognized the traffic control sign and chevron sign using foreside camera images. Also the highway alignment which is the basic information for highway drawing can be analyzed by acquisition the every 1m positional and attitude data using GPU and IMU sensor and developed algorithm. Finally, in this research the CAD based drawing software was developed to draw highway drawing using the analysis result from ARASEO. RESULTS : This study showed the comparison result of the surveyed road width and drawing data. To make the drawing of the road, we made the Autocad ARX program witch run in CAD menu interface. CONCLUSIONS : Using this program we can create the road center line, every 500m horizontal and vertical ground plan drawing automatically.

PURPOSES : This research is to analyze the influence in terms of misreading rate and legibility time for drivers when condensation occurs on the road signs. METHODS : In this research, the dew occurred road signs provided to drivers to measure legibility time and misreading rate to compare with normal road sign. In order to identify the difference of legibility time between normal road sign and dew occurred road sign, the T-test and ANOVA test were used. And the vision system was used to recognize the region of dew occurrence on the road sign, then the brightness of dew occurrence region on the road sign was changed to check the misreading rate of drivers according to the change rate of brightness. RESULTS : The legibility times were measured 2.65s for normal road sign and 4.08s for dew occurrence road sign and misreading rates were measured 2.8% for normal road sign, 21.7% for dew occurrence road sign.