PURPOSES : The turning movement of vehicles is directly affected by such factors as vehicle length, wheelbase, steering angle, articulated angle, and wheel steering. Therefore, it is necessary to analyze the impact of changes in each factor on the turning of the vehicle. Because a vehicle with a long body, such as an articulated bus, makes a wide turn, this study analyzes the swept path of the driving vehicle considering the specifications of the vehicle. METHODS : This study was conducted by dividing driving routes into four routes of two-lane four-way roundabouts, and the turning conditions were examined for six types (Type 1–6) that simulated actual articulated bus data. The same vehicle specifications as those of the actual articulated bus were applied to the road design simulation (AutoTURN Pro), and the width of the swept path for the articulated bus was investigated based on the wheel steering control. Using a virtual reference line for dividing the inscribed circle into lanes of the roundabout by 5°, the driving width of the swept path was measured and the angle at which the driving width was largest during driving through the turning intersection was examined. In addition, the changes in the driving width of the swept path according to the wheel steering control under the same wheel turning conditions, as well as the articulated and steering angles, were investigated. RESULTS : The driving width of the swept path for the vehicle (Type 1) with the front wheel control function being an all-wheel system was less than that of an articulated bus with the largest driving width of 15° after entering the roundabout and 15° before entering the roundabout (Type 2). Furthermore, although the specifications of the vehicles were the same, it was determined that Type 5 was superior to Type 6 after reviewing the driving width in light of changes in the steering and articulated angles. CONCLUSIONS : The results of this study are expected to contribute to the field of road design considering traffic safety when large vehicles, such as articulated buses, turn on roundabouts or curved road sections.

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 : In the case of a turning maneuver at an at-grade intersection or changing the driving path, the trajectory of a vehicle with a long body, such as a large bus or an articulated bus, should be analyzed from the perspective of road design. In this study, an articulated bus was selected to analyze the off-tracking, swept path width, and lane encroach hment for vehicle turning. METHODS : In this study, four scenarios were developed for right- and U-turn situations. For the right-turn situation, cases were divided into radii of 15 m (Scenario 1) and 40 m (Scenario 2). For the U-turn situation, the cases were analyzed based on a U-turn after stopping at the stop line (Scenario 3) and without stopping at the stop line for the U-turn (Scenario 4). Each scenario was examined at 5° (Right-turn) and 10° (U-turn) angles to analyze the off-tracking, swept path width, and lane encroachment. In addition, four Global Positioning System (GPS) antennas were installed on top of the articulated bus to obtain the driving trajectory of the vehicle. GPS locational reference points were marked on the testing ground to improve positioning accuracy. RESULTS : As a result of the right-turn analysis at an intersection radius of 15 m (Scenario 1), the average off-tracking per angle was 1.04 m, the average swept path width was 3.89 m, and the lane encroachments occurred at an angle of 65° to 70°. For the right-turn analysis at an intersection radius of 40 m (Scenario 2), the average off-tracking per angle was 3.71 m, and the average swept path width was 3.31 m. Unlike the results for the 15-m radius, no lane encroachment was found. Furthermore, the averages of the off-tracking in the at-grade intersection U-turn situation were 2.65 m (Scenario 3) and 2.54 m (Scenario 4), and the average swept path width was 6.15 m. CONCLUSIONS : The required driving width when an articulated bus performs a turning maneuver at an at-grade intersection was analyzed, revealing the implications that must be considered for busway design.

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 : The purpose of this study is to propose a method of quantitative bus deceleration and acceleration time based on automatic vehicle location data generated by a bus operating system. METHODS : The digital tachometer graph (DTG) data of commercial vehicles and the bus departure and arrival time data collected through the Korean bus information system (BIS) were matched and utilized to accurately reflect the deceleration and acceleration position of the bus. It was determined whether the bus arrived (or departed) at bus stations based on the BIS data, and the acceleration and deceleration times were calculated by classifying the bus status section (deceleration-stop-acceleration-driving) based on the DTG speed data. RESULTS : The deceleration and acceleration times calculated using the proposed method were analyzed using the z-test for the bus type and peak and non-peak times. Notably, there was a difference in the acceleration time for each vehicle type. The results were compared with the reference values of TCQSM and the calculated values, and the results were similar. CONCLUSIONS : This study is meaningful in that it conducted basic research on calculating the acceleration and deceleration times by fusing currently available data. In addition, new types of buses that have not been presented in the existing reference values have the advantage of being able to be calculated without a separate investigation if only data are produced according to the current bus management system.

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 : The purpose of this study is to review a method to estimate the average travel speed of the Bus Rapid Transit(BRT) section using the bus departure and arrival time data collected using the Korean bus information system (BIS). METHODS : To determine an average travel speed estimation model suitable for the BRT system in Korea, the speed estimated using the speed estimation model of TCQSM, which is used in the U.S., and that using the proposed speed estimation model that used the bus departure and arrival time data were compared with the actual travel speed using a t-test. RESULTS : The average travel speed estimated using the proposed method was more suitable for the actual average travel speed than that estimated using the TCQSM model. CONCLUSIONS : As a result of estimating the average travel speed, if the length of the link is 900 m, SBRT can be constructed on the existing road, but at least 1,200 m must be ensured to build SBRT in the new city. The proposed bus average travel speed estimation model can be used to review the BRT operational efficiency considering the speed limit, traffic signal, and dwelling time at bus stops in the planning and operation stages of the BRT.

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 : This study presents a specific methodology for air dispersion analysis of urban areas methodology in accordance with urban planning and transport policy. METHODS: This study performed three alternatives including development density and public transit applying integrated urban model for the Delft city on Netherlands. Based on this result, the two types of air pollutant emissions(PM10, NOx) were calculated and analyzed the emission dispersion on that City. RESULTS: As a result, the quality of air near the City is better than that of current conditions showed that approximately from 2.1 to 7.9% according to alternatives. CONCLUSIONS: Air quality assessment in urban areas can be reasonably performed by applying a methodology when urban development and transport policy are considered.

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.

PURPOSES : The objective of this study is to investigate the capability of the combined model of traffic simulation, emission and air dispersion models on the impact analysis of air quality of mobile sources such as vehicles. METHODS : The improvement of the quality of life brings about the increasing interest of the public environment. Many endeavors including the travel demand management, the application of the state-of-the-art ITS technologies, the promotion of eco-friendly vehicles have been tried in transportation area to reduce the modal emissions. Especially, it is expected that the increasing number of eco-friendly vehicles in the road network would be able to reduce the pipe-tail emissions tremendously. From this perspective, we have performed a study on the impact analysis of the popularization of the eco-friendly vehicle in the place of the fossil fuel energy powered vehicles on the surrounding air quality using the combined framework of microscopic traffic simulation, emission and air dispersion model. RESULTS : The combined model successfully captured the effect of moving to the eco-friendly vehicles on the air quality, and the results showed that the increasing usage of eco-friendly vehicles can improve the surrounding air quality tremendously and that the air dispersion model plays a crucial role in the investigation of the air quality change around the main corridor. CONCLUSIONS : This study demonstrated the capability of the combined model showing the spatio-tempral change of emission concentration.

PURPOSES : The purpose of this study is to check the possibilities of traffic pattern analysis using MatSIM for urban road network operation in incident case. METHODS : One of the stochastic dynamic models is MatSIM. MatSIM is a transportation simulation tool based on stochastic dynamic model and activity based model. It is an open source software developed by IVT, ETH zurich, Switzerland. In MatSIM, various scenario comparison analyses are possible and analyses results are expressed using the visualizer which shows individual vehicle movements and traffic patterns. In this study, trip distribution in 24-hour, traffic volume, and travel speed using MatSIM are similar to those of measured values. Therefore, results of MatSIM are reasonable comparing with measured values. Traffic patterns are changed according to incident from change of individual behavior. RESULTS : The simulation results and the actual measured values are similar. The simulation results show reasonable ranges which can be used for traffic pattern analysis. CONCLUSIONS : The change of traffic pattern including trip distribution, traffic volumes and speeds according to various incident scenarios can be used for traffic control policy decision to provide effective operation of urban road network.

도로표지는 운전자에게 정보제공의 역할을 하는 도로시설물로서 주행경로에 대한 운전자의 판단을 도와준다. 그러나, 주 야간의 온도, 습도 변화로 인한 도로표지판에 결로발생 시, 정보전달의 결함이 발생하여 교통사고 가능성을 높이는 원인으로 작용한다. 따라서, 도로표지판의 결로발생을 예방하기 위한 기술이 필요하다. 본 연구에서는 도로표지판의 결로발생을 예방하는 대안의 효과를 비교하기 위해 단열소재가 삽입된 시편, 결로방지필름이 부착된 시편을 선정하고 결로방지처리가 되지 않은 일반시편과 비교하였다. 분산분석과 사후검정(Tukey HSD)을 통해 각 시편에 발생한 측정시간에 따른 결로량을 비교 했으며, 결로량과 재귀반사도의 관계를 Pearson의 상관분석으로써 검증하였다. 분석결과, 결로방지필름이 부착된 시편에서 결로량이 적게 나타났으며, 결로발생 90초 후에는 결로방지필름의 부착 시편과 단열소재가 삽입된 시편에서 나타나는 결로량은 결로방지 처리가 되지 않은 시편에서 발생한 결로량과의 통계적인 차이가 존재하였다. 또한, 상관분석결과로써 결로량과 재귀반사도는 반비례하는 것으로 나타났다. 따라서, 도로표지판에 발생된 결로량과 재귀반사 변화율에 대하여, 결로방지필름의 부착과 단열소재의 삽입은 결로방지에 효과가 존재하는 것으로 판단된다.

차선을 벗어난 승용차가 기초에 강결된 표지판 지주에 충돌할 경우 차량이 받는 충격과 변형은 탑승자의 안전을 위협하게 되므로 분리지주를 쓰는 것이 일반적이다. 국도에서 1200mm×1200mm의 단일노선표지에 사용되는 직경 101.6mm, 두께 4.0mm의 강관지주가 기초에 강결되었을 때와 Clip형 분리장치를 갖는 경우에 대한 820kg-50kg-정면 충돌 시 차량과 지주의 거동을 LS-DYNA 시뮬레이션을 통하여 비교 분석하였다. 분리식 지주 충돌 시뮬레이션 결과는 동일한 조건의 충돌실험 결과와 비교하여 신뢰도를 높였다. 강결된 원형지주에 대한 충돌 시뮬레이션 결과 탑승자 안전지수(THIV, PHD)와 차량의 변위가 탑승자의 안전을 위협하는 수준으로 나타났으나 Clip형 분리장치를 갖는 지주에 대한 충돌 시뮬레이션 결과 충돌 시 지주의 분리로 감속도가 현저히 줄어들어 안전한 것으로 확인되었다.

기초에 강결되어 도로변에 노출된 각종 지주는 정면충돌 뿐 아니라 측면충돌에 특히 위험하다. 클립형 단부분리장치를 갖는 지주는 정면충돌에 효과적이고 다방향으로 분리가 가능하기 때문에 측면충돌에도 효과적이다. 본 논문은 강결된 지주의 측면충돌에 대한 위험성을 보이고 클립형 단부분리장치를 갖는 지주의 충격완화 효과를 보이기 위하여 측면충돌실험을 실시하고 그 결과를 분석 정리한 것이다. 이를 위하여 미국의 NCHRP Report 350을 기반으로 측면충돌의 기준을 제시하고 D101.6mm(t=4.2mm)의 지주가 강결된 경우와 클립형 단부분리장치로 연결된 경우에 대하여 820kg의 소형차로 충돌속도 50km/h의 측면충돌실험을 실시하였고 단부장치의 저속분리가 가능한가를 35km/h의 측면충돌실험으로 확인하였다. 강결지주는 차량의 과다한 변형 및 전복, 안전지수 측면에서 측면충돌에 치명적이지만 클립형 단부분리장치로 기초에 연결된 경우 충돌피해를 크게 줄일 수 있음을 확인하였다.

도로의 안전성은 종단선형, 평면선형, 횡단경사(편경사), 노면온도 등 여러 가지 요인에 의하여 결정되며 이러한 각종 데이터는 도면으로 구하기 어렵고 실제 도면과 현황 데이터가 포장의 덧씌우기 등으로 달라지는 경우가 있다. 이러한 데이터를 측량하기 위해서는 많은 시간과 비용이 필요하고 차량의 통행이 빈번한 곳에서는 위험한 작업이 될 수 있다. 본 연구에서는 한국건설기술연구원의 도로 안전성 조사 분석차량인 RoSSAV(Road Safety Survey & Analysis Vehicle) 차량을 이용하여 주변 교통류 속도와 맞추어 차량에 부착된 GPS-INS와 회전식 레이저를 이용하여 도로의 횡단경사를 취득하고 분석을 통하여 도로의 안전성을 분석하고 도로의 안전성 개선방향에 대하여 제시하였다. 이를 위하여 측정된 값의 정확도를 비교하였으며 회전식 레이저데이터 처리 알고리즘을 제시하였다.