PURPOSES : This study evaluates the effectiveness of traffic flow optimization when giving safety strategy guidance to a connected autonomous vehicle (CAV) based on information received through infrastructure cooperation in a V2X environment for non-signal intersection. METHODS : To evaluate the effectiveness of safety strategy guidance based on developed traffic flow control algorithm at a non-signalized intersection, it was implemented on simulation. A scenario based on the Level of Service (LOS) and the market penetration rate(MPR) of autonomous vehicles was established. The simulation results were divided into safety, operation, and environment to evaluate the effect, and the effect of optimizing traffic flow was finally derived through the integrated evaluation score. RESULTS : As a result, when safety strategy guidance was provided, the number of conflicts and CO emissions decreased by about 29% and about 15%, improving safety and environmental performance. In the case of operation, the mean of delay time was increased overall by 1%, but in the case of MPR 50 and above, the delay time was reduced by about 38%, thereby increasing operation. Finally, the aspect of traffic flow optimization, effectiveness of safety strategy guidance was derived through the integrated evaluation score, and the average integrated evaluation score improved from MPR 20 or higher. CONCLUSIONS : Providing guidance had the effect of optimizing traffic flow at a non-signal intersection. In the future, V2X communications will provide CAV with algorithm-based guidance developed in this study to control driving behavior. it will support safe and efficient driving at non-signal intersections.

PURPOSES : This paper proposes an artificial neural network (ANN)-based real-time traffic signal time design model using real-time field data available at intersections equipped with smart intersections. The proposed model generates suitable traffic signal timings for the next cycle, which are assumed to be near the optimal values based on a set of counted directional real-time traffic volumes. METHODS : A training dataset of optimal traffic signal timing data was prepared through the CORSIM Optimal Signal Timing program developed for this study to find the best signal timings, minimizing intersection control delays estimated with CORSIM and a heuristic searching method. The proposed traffic signal timing design model was developed using a training dataset and an ANN learning process. To determine the difference between the traditional pre-time model primarily used in practice and the proposed model, a comparison test was conducted with historical data obtained for a month at a specific intersection in Uiwang, Korea. RESULTS : The test results revealed that the proposed method could reduce control delays for most of the day compared to the existing methods, excluding the peak hour periods when control delays were similar. This is because existing methods focus only on peak times in practice. CONCLUSIONS : The results indicate that the proposed method enhances the performance of traffic signal systems because it rapidly provides alternatives for all-day cycle periods. This would also reduce the management cost (repeated field data collection) required to increase the performance to that level. A robust traffic-signal timing design model (e.g., ANN) is required to handle various combinations of directional demands.

PURPOSES : This study aims to develop and validate timing transition techniques for real-time traffic signal operations, departing from conventional methods based on past commuting traffic patterns. METHODS : In this study, we propose two traffic signal transition techniques that can perform transitions while minimizing disruptions within a short period. The Proposed 1 technique involves an unconditional transition within one cycle and allows for the allocation of offset changes to both the coordinated and non-coordinated phases. The Proposed 2 technique performs transitions within 1-2 cycles based on the offset change rate and considers the non-coordinated phase for allocating offset changes. RESULTS : Functional improvements of the proposed techniques were validated. For validation, simulated traffic signal transition scenarios were created, and a comparative analysis of the transition techniques was performed based on the selected analysis approaches. The results showed that the Proposed 1 technique exhibited the lowest delay during the approximated saturated transitions, whereas the Subtract technique showed the lowest delay during the non-saturated transitions. CONCLUSIONS : These findings emphasize the importance of selecting and applying appropriate transition techniques tailored to individual traffic scenarios. The proposed transition techniques provide valuable insights for improving real-time traffic signal operations, and contribute to the overall efficiency and effectiveness of traffic management in highway corridors.

PURPOSES : This study proposes brief guidelines for traffic engineers in the field to refer to when operating tram priority signals based on the "early green" and "green extension" methods. METHODS : A set of VISSIM simulation analyses was conducted considering various traffic and control conditions in a hypothetical corridor consisting of two signalized intersections. The traffic conditions were varied at five different levels. The control conditions were varied at twenty-five levels by changing the tram priority traffic signal control parameters, i.e., the early green unit time and green extension unit time. A total of 125 simulation runs were from these combinations. A set of optimal signal timings for ordinary non-tram vehicles was prepared with TRANSYT-7F and implemented for the simulation. A tram priority signal control module based on VISVAP was exclusively developed for this study. RESULTS : As expected, no specific trend was found in the relationship between the two tram priority control parameters (early green time and green extension time). However, a trend was observed when assuming that the early green and green extension operations were mutually exclusive. Specifically, an inverse trend appeared between the tram priority control parameter values and level of congestion according to the performance measure (average network delay). CONCLUSIONS : For the early green control parameters, it is better to provide six seconds when undersaturated and four seconds when near-saturated. For the green extension control parameter, four seconds is suitable.

PURPOSES : In this paper, pedestrian-oriented time assured traffic operation (POTATO), adopted in Korea at a single crossing pedestrianoriented operating area, is explored and applied to a simulation experiment and test site to verify the operation efficiency. METHODS : Three candidate plans are presented as a method to operate pedestrian-oriented signal operations that can overcome the restrictions on signal controllers in Korea. The selected POTATO and TOD signal operations were compared and analyzed. The delay and pedestrian queues, present length, and number of times were used as comparative indices. RESULTS : Scenario-specific simulations confirmed that the delay, compared to TOD signal operation, was reduced by up to 5 s/ped depending on the vehicle traffic volume and the number of pedestrians. For the vehicle delay, the results increased up to 8.99 s/veh, depending on the traffic volume of the vehicles and pedestrians. As a result of the test site operation, POTATO operation improved by 5.12 s/ped (approximately 46.69% improvement) compared to TOD operation in the hours commuting to school and by 2.84 s/ped in the hours commuting from school (approximately 51.13% improvement). In case of vehicle delay, the delay increased by 2.35 s/veh (approximately 64.39%) in the hours commuting to school and 1.20 s/veh (approximately 21.11%) in the hours commuting from school compared to the TOD operation. CONCLUSIONS : Through simulations and test site pilot operation verifications, the effects of pedestrian delay improvement were more positive if POTATO proposed in this study was low in vehicle traffic.

PURPOSES: This paper presents the development and evaluation of the smart hardware-in-the-loop systems (SMART-HILS) that evaluate traffic signal operations of a new real-time traffic signal control system called SMART SIGNAL at the traffic management center (TMC) level. METHODS: The layouts of the hardware and software components of the SMART-HILS were introduced in this study and its performance was tested using real-time traffic signal operation algorithms embedded in the SMART SIGNAL control server by utilizing the VISSIM simulation model. In this study, the SMART-HILS management software was developed using .NET programming language. Fewer random seed numbers were used for the test scenarios by conducting statistical tests to address the shortcomings of a longer time due to the adoption of the simulation time as the real-time by the TMC server. RESULTS : It was determined that SMART-HILS can communicate with TMC and VISSIM for both upload and download directions within acceptable time constraints and evaluate new design algorithms for traffic signal timing. CONCLUSIONS : In practice, traffic engineers can utilize SMART-HILS for testing the traffic signal operation alternatives before their selection and implementation. This application could increase the productivity of traffic signal operation.

PURPOSES : The purpose of this study is to develop a service volume for signal metering on roundabouts to increase applicability of roundabout in Korea. METHODS: To develop the service volume for signal metering on roundabouts, traffic simulation studies were conducted using VISSIM software for various scenarios based on traffic volumes as approaches and location of detectors on controlling approach lane. Typically, the Vehicle Actuated Programming module in VISSIM was applied for analyzing more realistic traffic signal control conditions. RESULTS: As the left-turning volume is increased, the delay reduction rates were increased. And the case of 40 meter distance of a detector and 20 seconds red signal phase made better results. CONCLUSIONS: The signal metering on roundabout should be applied carefully because it is possible to lose roundabout strengthen in traffic operation aspect. The service volume for signal metering on roundabouts that suggested from this study is useful to decide the application of signal metering on roundabout.

PURPOSES : In this study, analyze the characteristics of IOC indicator 'threshold' which is needed when evaluating the traffic signal operation status with ESPRESSO in various grade road traffic environment of Seoul metropolitan city and derive suggested value to use in field practice. METHODS : Using the computerized database program (Postgresql), we extracted data with regional characteristics (Arterial, Collector road) and temporal characteristics (peak hour, non-peak hour). Analysis of variance and Duncan's validation were performed using statistical analysis program (SPSS) to confirm whether the extracted data contains statistical significance. RESULTS: The analysis period of the main and secondary arterial roads was confirmed to be suitable from 14 days to 60 days. For the arterial, it is suggested to use 20 km/h as the critical speed for PM peak hour and weekly non peak hour. It is suggested to use 25 km/h as the critical speed for AM peak hour and night non peak hour. As for the collector road, it is suggested to use 20 km/h as the critical speed for PM peak hour and weekly non peak hour. It is suggested to use 30 km/h as the critical speed for AM peak hour and night non peak hour. CONCLUSIONS : It is meaningful from a methodological point of view that it is possible to make a reasonable comparative analysis on the signal intersection pre-post analysis when the signal operation DB is renewed by breaking the existing traffic signal operation evaluation method.

PURPOSES: The purpose of this study is to develop a crash prediction model at signalized intersections, which can capture the randomness and uncertainty of traffic accident forecasting in order to provide more precise results. METHODS: The authors propose a random parameter (RP) approach to overcome the limitation of the Count model that cannot consider the heterogeneity of the assigned locations or road sections. For the model’s development, 55 intersections located in the Daejeon metropolitan area were selected as the scope of the study, and panel data such as the number of crashes, traffic volume, and intersection geometry at each intersection were collected for the analysis. RESULTS: Based on the results of the RP negative binomial crash prediction model developed in this study, it was found that the independent variables such as the log form of average annual traffic volume, presence or absence of left-turn lanes on major roads, presence or absence of right-turn lanes on minor roads, and the number of crosswalks were statistically significant random parameters, and this showed that the variables have a heterogeneous influence on individual intersections. CONCLUSIONS : It was found that the RP model had a better fit to the data than the fixed parameters (FP) model since the RP model reflects the heterogeneity of the individual observations and captures the inconsistent and biased effects.

도로를 통행하는 운전자는 경험에 의한 경로 선택을 하기에 앞서 실시간 교통정보를 활용하여 혼잡이 덜하고 목적지까지의 최소 소통 시간이 보장되는 경로를 활용하는 추세를 보이고 있다. 또한 교통 정보의 영향을 받는 산업이 점진적으로 증가함에 따라 교통 정보의 요구는 확대 일로에 있는 추세이다. 과히 스마트폰의 붐이라 할 정도로 스마트 기기의 보급이 증대하고 더불어서 모바일 콘텐츠의 요구는 점진적으로 확대되고 있으며, 다른 부문과 견주어서도 자동차와 연계된 교통정보의 요구는 과히 폭발적으로 증가하고 있다고 할 수 있다. 교통정보는 필수적으로 정보 신뢰성을 갖추어야 하며, 교통정보 수집을 위해 많은 교통 검지기의 설치가 요구되고 있다. 기존 교통정보의 수집은 교통 검지기를 설치하여 지점의 교통자료를 검지하는 지점 검지 방식이며, 루프 검지기, 레이더 검지기, 지자기 검지기 등이 있다. 지점 검지기는 설치된 지점의 교통 정보를 간단한 방식으로 실시간 검지한다는 장점이 있으나, 교차로, 일부 구간 정체 등 구간의 대표 교통정보를 위해서는 좁은 간격으로 설치하여야 하므로 많은 수량의 검지기가 요구된다. 그러므로, 구간 통행시간 측정이 가능한 구간 검지 방식으로 점진적으로 전환하고 있는 추세이다. 번호판 검지기(AVI), DSRC 검지기 등이 이러한 구간 검지 방식의 교통 검지기이다. 본 논문에서는 차량 내에 탑승자들이 소지한 스마트 기기의 블루투스, 와이파이 무선 통신 신호를 검지하여, 구간 검지 방식으로 무선신호 매칭을 통해 교통정보를 산출하는 교통정보 수집장치를 개발하였으며, 현장 평가를 수행하고 분석 결과를 제시하고자 한다. 스마트기기 무선신호를 활용한 교통정보 수집장치는 각 통신모듈에 유일한 Mac 주소를 수집 분석하는 방식을 사용한다. 그리고, 기존 교통검지기는 전기 및 유선통신 인프라를 기반으로 운영되어 이동성의 제약을 극복하고자 이동이 가능한 소형화 및 배터리 운영이 가능하도록 설계 제작하였다. 무전원 상태에서도 10일 이상의 운용이 가능하며, 소형화함에도 불구하고 기존 교통 검지기와 동등한 성능을 가지도록 개발 목표를 설정하였다. 이천시 곤지암IC 부근의 일반국도 3호선에서 두 조의 수집장치를 4km 간격으로 설치하여 오전 10시부터 7시간 현장 평가를 수행하였다. 전체 통행 차량의 30% 내외의 무선신호를 검지할 수 있었으며, 블루투스 무선신호보다 와이파이 무선신호가 3배 많은 빈도로 검지됨을 확인하였으며, 이로부터 산출된 통행시간은 비교적 현장 교통정보를 반영한 통행시간이 산출됨을 확인하였다. 개발된 교통정보 수집장치는 소형, 경량화 및 배터리 사용 설계를 통해 운영 환경에 영향받지 않고 간편하게 이동식으로 교통정보를 수집할 수 있음을 확인하였다. 사용자들의 스마트폰 사용 패턴으로 30% 정도만이 수집되었으나, 성능 지표 측면에서 고가의 교통 검지기를 대체할 수 있는 이동식 장비로서 운영이 가능함을 확인하였다.

PURPOSES: The objective of this study was to analyze variations in the vehicle driving behavior characteristics on signalized intersections according to the use of traffic enforcement camera (red light camera). METHODS: In order to analyze the driving behavior characteristics on signalized intersections when red light camera are installed, the target sites for investigation were selected depending on whether the red light camera is installed and accident rates increased after the installation. In particular, to analyze the characteristics of dilemma zones in signalized intersections, approach speed and deceleration speed of 3 type vehicles (passing vehicles during a yellow light, stopping at a yellow light, passing vehicles during a green light) were examined. Based on these data, the starting point, ending point, and distance of the dilemma zones were calculated. Also, the locations of increased traffic accidents and decreased accidents after the installation of the equipment were distinguished when analyzing the traffic accident characteristics. RESULTS : Analysis results revealed that there was a tendency for the dilemma zone distance to decrease after the installation of equipment(red light camera) in most sites. This tendency was found to be due to the decrease in the approaching speed of vehicles at intersections after the installation of equipment, resulting in the starting and ending points of dilemma zone to become closer to the stop line. Moreover, analysis showed that the number of traffic accidents decreased for most intersections after the installation of equipment and safety of the intersections increased somewhat. CONCLUSIONS : In general, installation of equipment(red light camera) caused the intersections approaching speed and dilemma zone distance to decrease. Decision-making is difficult for drivers in the dilemma zone, so the decrease in the dilemma zone distance implies an improvement in traffic safety. Furthermore, the number of accidents within intersections significantly decreased after the equipment was installed, leading to the conclusion that installation of the equipment affected the decrease in traffic accidents.

정보통신과 스마트 기기의 급속한 발전은 정보제공 서비스 산업의 발전을 견인해왔고, 이에 따라 다수 의 교통정보 제공 업체(ISP, Information Service Provider)가 시장에 등장하였다. 운전자들은 ISP로부 터 제공받은 교통정보를 기반으로 목적지까지 합리적인 경로를 선택하여 통행을 한다. 교통운영기관 (TMC, Traffic Management Center)은 교통수요정책과 같은 적극적(active) 방법뿐만 아니라 최적 신호 제어와 같은 소극적(passive) 방법을 통해 교통혼잡을 완화하기 위해 노력한다. 이와 같이 도로교통망에 서는 TMC와 ISP, 운전자들이 개별적으로 최적의 선택을 하지만, 서로 상호작용하며 종국의 교통상황을 만들어낸다. 그동안 개별적인 통행 주체에 대해서는 많은 연구가 수행되어 왔지만, 이들 세 주체 간의 상 호작용에 대해서는 많은 연구가 이루어지지 않았다. 이에 본 연구에서는 교통운영기관과 교통정보제공업 체, 운전자 경로선택 간의 상호작용을 분석할 수 있는 통합 모델링 프레임워크를 개발하였다. 그림 1은 통합 모델링 프레임워크의 개념도를 나타낸다. 운전자는 ISP 가입자와 비가입자로 구성되고, 가입자는 제공받은 교통정보를 기반으로 경로를 선택하는 반면, 비가입자는 스스로의 경험에 따라 경로를 선택하는 데, 경로선택 모형으로는 Boundedly Rational 모형을 채택하였다. 교통정보제공서비스는 가입자를 통해 수집된 교통정보와 예측된 정보를 혼합하여 가입자들에게 최적의 경로를 안내해 준다. 교통운영기관은 실 시간 교통 모니터링 시스템을 통해 수집된 교통정보와 예측된 정보를 혼합하여 최적의 실시간 교통신호제 어를 수행한다. 교통신호제어는 두 가지 방식이 제안되었는데, 첫 번째 방식은 실시간 교차로 접근 교통 량 기반의 신호제어 방식(R2CFNet)이고, 두 번째 방식은 예측된 경로 기반으로 신호를 제어하는 방식 (R2CFNet)이다. 제안된 프레임워크를 활용하여 ISP의 시장점유율별 도로교통망 성능(performance)을 분석한 결과, 시장점유율이 증가함에 따라 R2CFNet 신호제어 방식이 더 효율적인 것으로 나타났다.