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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korean Society of Transportation
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Journal DOI :
Korean Society of Transportation
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Volume & Issues
Volume 22, Issue 7 - Dec 2004
Volume 22, Issue 4 - Aug 2004
Volume 22, Issue 3 - Jun 2004
Volume 22, Issue 2 - Apr 2004
Volume 22, Issue 1 - Feb 2004
Volume 22, Issue 6 - Jan 2004
Volume 22, Issue 5 - Jan 2004
Selecting the target year
Distribution Characteristic Analysis for Link Travel Time Using GPS Data
Lee, Young-Woo ; Lim, Chae-Moon ;
Journal of Korean Society of Transportation, volume 22, issue 5, 2004, Pages 7~17
Most research for until at now link travel time were performed for mean link travel time calculate or estimate which uses the average of the individual vehicle. However, the link travel time distribution is divided by the impact factor, which is various traffic condition, signal operation condition and the road conditional etc. Consequently, a link travel time charateristic is a necessity which it will analyze with the detail. This research is conducted for the methods of colecting real-time traffic data and real-time traffic data colection using GPS-based RTK assessment to proceed with the study on link travel time. Also, it executed the field test for link travel time which analyzes the link travel time distribution characteristic caused by with the effect due to the signal operation additionally. It analyzed transit hour distribution characteristics and a cause using field test data and examine to the variables. which give an effect at link travel time distribute using simulation program and determinate link travel time distribute ratio estimation model. The result of analyzing driving experiment using a GPS equipped car is link travel time was classified into two cases, one travel time in which cars did not experience signal delay and which was composed of cruising time only, and the other travel time in which cars experienced a signal delay and which was composed of cruising time and one signal delay time. Therefore, it is desirable to consider two separate travel time concurrently rather than only one averaged travel time when analyzing link travel time. This study result for link travel time distribution characteristic showed that the patterns of going through traffic were divided up to 2 in the link travel times. Therefore, it will be more accurate to divide up the link travel time into the one involving delay and the other without delay, rather than using the average link travel time in terms of assessing the traffic situation.
Phasing and Sequencing Design Techniques at a Signalized Intersection
Cho, Jun-Han ; Kim, Seong-Ho ; Doh, Tcheol-Woong ;
Journal of Korean Society of Transportation, volume 22, issue 5, 2004, Pages 19~33
The phasing and sequencing of a traffic signal affect both the safety with which the intersection operates and the efficiency of movement provided to motorists and pedestrian. However, phasing and sequencing are determined by traffic engineer's experience or heuristic rule without typical guidelines so far. Also, none of the computer software can optimize all four traffic control parameters(i.e, cycle length, green spit, offset and phase sequence) simultaneously, even for the undersaturated condition. In this paper, a new optimization approach for the various traffic conditions is presented using heuristic method based on TRANSYT-7F release 8.2. The stages of the new phasing and sequencing design techniques are as follows. First, we establish a phase sequence design technique. Second, we calibrate a embeded parameters of TRANSYT-7F. Third, we determine an optimal phase sequence using TRANSYT-7F, Forth, we evaluate through NETSIM MOEs with TRANSYT-7F's result. Based on the results presented in this paper, it can be suggested that urban and local streets for pretimed signal system without surveillance system improve efficiency of intersection operation.
An Evaluation of Service Quality Priorities between Air Cargo Service Providers and Customers
Jun, Il-Soo ; Hong, Seok-Jin ;
Journal of Korean Society of Transportation, volume 22, issue 5, 2004, Pages 35~45
This paper analyzes the differences in the service quality priorities of air cargo service providers and customers. After having identified what constitutes the decisive factors with regards to air cargo service quslity, research was carried out to evaluate the differences in the service quality priorities of air cargo service providers and customers. Moreover, this paper analyzes these differences by separating air cargo service providers into Korean and international air cargo service providers. In order to attain the objectives of this research, the air cargo service sectors were divided into three general categories: supply capability(H/W), service accountability, and competitiveness of service fees and management capability(S/W). The researchers then placed 6 different criteria into each service category, for a total of 18. The evaluation of the service quality priorities of air cargo service providers and customers revealed very little difference between these two groups. With regards to the service criteria found in each service category, our research found marked differences between the service quality priorities of providers and customers in only three of the 18 criteria. However, we found marked differences in service quality priorities in 7 of the 18 criteria when the air cargo service providers were divided into Korean and international air cargo providers. While domestic air cargo service providers evaluated management's capability to handle cargo accidents and incidents as the most important priority, international air cargo service providers placed the highest priority on the cargo rate system. The results of this research imply that in order to properly evaluate the differences between the service quality priorities of air cargo service providers and customers, the air cargo service providers itself should be separated between the Korean air cargo service providers and the foreign providers because of their respective inherent perception on service quality.
Introduction to Areawide Road Safety Improvement Programs
Han, Sang-Jin ; Park, Byung-Jung ; Yoon, Kong-Hyun ;
Journal of Korean Society of Transportation, volume 22, issue 5, 2004, Pages 47~57
This study introduces the areawide road safety improvement program, which was developed to overcome the weak points of conventional black spot improvement programs. The latter has been criticized in terms of that it can cause the problem of accident migration and that it prevents from identifying causes of road accident in the comprehensive scope. On the other hand, the areawide road safety improvement program can allow us to find the route or areas that have quite a number of road accidents with the common causes. Therefore, we can take countermeasures effectively in a different framework in this approach. This study explains in detail about the concept, procedures, and effects of areawide road safety improvement programs including the example. This study may contribute to bringing a new framework of road safety improvement program in Korea.
A Coarse Grid Method for the Real-Time Route Search in a Large Network
Kim, Seong-In ; Kim, Hyun-Gi ;
Journal of Korean Society of Transportation, volume 22, issue 5, 2004, Pages 61~73
The efficiency of the real-time route guidance system(RGS) depends largely on the quality of route search algorithms. In this paper, we implement the coarse grid method(CGM) in mathematical programming for finding a good quality route of real-time RGS in large-scale networks. The proposed CGM examines coarser and wider networks as the search phase proceeds, in stead of searching the whole network at once. Naturally, we can significantly reduce computational efforts in terms of search time and memory requirement. We demonstrate the practical effectiveness of the proposed CGM with nationwide real road network simulation.
A Study on Variable Speed Limit Considering Wind Resistance on Off-Shore Bridge
Lee, Seon-Ha ; Kang, Hee-Chan ;
Journal of Korean Society of Transportation, volume 22, issue 5, 2004, Pages 75~87
Along the seashore regions in Korea, though strong winds with very large strength are frequently witnessed, no system which can provide appropriate speed information for driving vehicle has been introduced. The driving against strong winds could be very dangerous because of the high possibility of accidents such as rollover and collision. These accidents usually resulted from driver's forced driving try even in difficult situation for steering vehicle, and sometimes overspeed without consideration of wind impact to the vehicles. To reduce accident caused by strong winds, it is important to inform drivers of appropriate driving speeds by perceiving strong winds. By setting up WIS at the main points where strong winds frequently appear and using the variable message sign(VMS) connected to the on-line whether information system, it tis possible to provide desired speed information, which can maintain vehicles' tractive force and maximum running resistance. The case study is conducted on the case of Mokpo-Big-Bridge, which is under construction at Mokpo city. The result show that in case the annual average direction of wind is South and the wind speed is over 8m/hr, the desired speed, which is required in order for vehicles running to South direction to maintain the marginal driving power, is 60km/hr. In addition, for the case of a typhoon such as Memi generated in 2003 year, if wind speed had been 18m/sec in Mokpo city at that time, the running resistance at the speed of 40km/hr is calculated as 1131N. This resistance can not be overcome at the 4th gear(1054N) level, therefore, the gear of vehicles should be reduced down to the 3rd level. In this case, the appropriate speed is 40km/h, and at this point the biggest difference between running resistance and tractive force is generated.
Forecasting Air Freight Demand in Air forces by Time Series Analysis and Optimizing Air Routing Problem with One Depot
Jung, Byung-Ho ; Kim, Ik-Ki ;
Journal of Korean Society of Transportation, volume 22, issue 5, 2004, Pages 89~97
The Korea Air Force(KAF) has operated freight flights based on the prefixed time and route schedule, which is adjusted once in a month. The major purpose of the operation of freight flights in the KAF is to distribute necessary supplies from the home air base to other air bases. The secondary purpose is to train the young pilots to get more experiences in navigation. Each freight flight starts from and returned to the home air base everyday except holidays, while it visits several other air bases to accomplish its missions. The study aims to forecast freight demand at each base by using time series analysis, and then it tried to optimize the cost of operating flights by solving vehicle routing problem. For more specifically, first, several constraints in operating cargos were defined by reviewing the Korea Air Force manuals and regulation. With such constraints, an integer programming problem was formulated for this specific routing problem allowing several visits in a tour with limitation of maximum number of visits. Then, an algorithm to solve the routing problem was developed. Second, the time series analysis method was applied to find out the freight demand at each air base from the mother air base in the next month. With the forecasted demands and the developed solution algorithm, the oprimum routes are calculated for each flight. Finally, the study compared the solved routing system by the developed algorithm with the existing routing system of the Korea Air Force. Through this comparison, the study proved that the proposed method can provide more (economically) efficient routing system than the existing system in terms of computing and monetary cost. In summary, the study suggested objective criteria for air routing plan in the KAF. It also developed the methods which could forecast properly the freight demands at each bases by using time series analysis and which could find the optimum routing which minimizes number of cargo needed. Finally, the study showed the economical savings with the optimized routing system by using real case example.
A Study on Characteristics of Traffic Flow in Congested Traffic at On-Ramp Influence Area
Kim, Sang-Gu ; Kim, Young-Ho ; Kim, Tae-Wan ; Son, Young-Tae ;
Journal of Korean Society of Transportation, volume 22, issue 5, 2004, Pages 99~109
Most traffic congestion on a freeway occurs in the merge area, where conflicts between mainline traffic and on-ramp traffic are frequently generated. So far, research on the merge area has mainly dealt with free flow traffic and research on the congested traffic at the merge area is rare. This study investigates the relationships between mainline traffic and on-ramp traffic at three different segments of the merge area. For this purpose, new indicators based on such traffic variables as flow, speed, and density are used. The results show that a negative relationship exists between mainline and on-ramp flow. It is also found that the speed and the density of the right two lanes in the mainline traffic are significantly affected by the on-ramp flow. Based on the correlation analysis of the indicators, it is confirmed that the ramp influence area is the right two lanes of the freeway mainline. The revealed relationships between mainline and on-ramp traffic may help to analyze the capacity of the downstream freeway segment of the merging area in congested traffic. The findings of this studyalso provide a basis to develop a model that estimates the merge traffic volume in congested traffic, which is neither theoretically nor empirically sound in most other traffic flow models developed so far.
Effect of Guidance Information Receiving Ratio on Driver's Route Choice Behavior and Learming Process
Do, Myung-Sik ; Sheok, Chong-Soo ; Chae, Jeung-Hwan ;
Journal of Korean Society of Transportation, volume 22, issue 5, 2004, Pages 111~122
The driver's decision making (e.g. route choice) is a typical decision making with an uncertainty. In this paper, we investigate the effect of route guidance information on driver's route choice and learning behavior and analyse the potential of information system in a road network in which traffic flows follow random walk. A Simulation performed focuses on the relationship among the network wide performance, message receiving rates and driver's learning mechanism. We know that at high levels of message receiving rates, the network-wide performance may get worse. However, at low levels of receiving rates, we found that the travel time when guidance information is provided decrease compared to the cases when no pubic information is provided. Also, we found that the learning parameter of the learning mechanism model always changes under nonstationary traffic condition. In addition, learning process of drivers does not converge on any specific value. More investigation is needed to enlarge the scope of the study and to explore more deeply driver's behavior.
The Development of Predictive Multiclass Dynamic Traffic Assignment Model and Algorithm
Kang, Jin-Gu ; Park, Jin-Hee ; Lee, Young-Ihn ; Won, Jai-Mu ; Ryu, Si-Kyun ;
Journal of Korean Society of Transportation, volume 22, issue 5, 2004, Pages 123~137
The study on traffic assignment is actively being performed which reflect networks status using time. Its background is increasing social needs to use traffic assignment models in not only hardware area of road network plan but also software area of traffic management or control. In addition, multi-class traffic assignment model is receiving study in order to fill a gap between theory and practice of traffic assignment model. This model is made up of two, one of which is multi-driver class and the other multi-vehicle class. The latter is the more realistic because it can be combined with dynamic model. On this background, this study is to build multidynamic model combining the above-mentioned two areas. This has been a theoretic pillar of ITS in which dynamic user equilibrium assignment model is now made an issue, therefore more realistic dynamic model is expected to be built by combining it with multi-class model. In case of multi-vehicle, FIFO would be violated which is necessary to build the dynamic assignment model. This means that it is impossible to build multi-vehicle dynamic model with the existing dynamic assignment modelling method built under the conditions of FIFO. This study builds dynamic network model which could relieve the FIFO conditions. At the same time, simulation method, one of the existing network loading method, is modified to be applied to this study. Also, as a solution(algorithm) area, time dependent shortest path algorithm which has been modified from existing shortest path algorithm and the existing MSA modified algorithm are built. The convergence of the algorithm is examined which is built by calculating dynamic user equilibrium solution adopting the model and algorithm and grid network.
Development of a Model for Calculating Road Congestion Toll with Sensitivity Analysis
Kim, Byung-Kwan ; Lim, Yong-Taek ; Lim, Kang-Won ;
Journal of Korean Society of Transportation, volume 22, issue 5, 2004, Pages 139~149
As the expansion of road capacity has become impractical in many urban areas, congestion pricing has been widely considered as an effective method to reduce urban traffic congestion in recent years. The principal reason is that the congestion pricing may lead the user equilibrium (UE) flow pattern to system optimum (SO) pattern in road network. In the context of network equilibrium, the link tolls according to the marginal cost pricing principle can user an UE flow to a SO pattern. Thus, the pricing method offers an efficient tool for moving toward system optimal traffic conditions on the network. This paper proposes a continuous network design program (CNDP) in network equilibrium condition, in order to find optimal congestion toll for maximizing net economic benefit (NEB). The model could be formulated as a bi-level program with continuous variable(congestion toll) such that the upper level problem is for maximizing the NEB in elastic demand, while the lower level is for describing route choice of road users. The bi-level CNDP is intrinsically nonlinear, non-convex, and hence it might be difficult to solve. So, we suggest a heuristic solution algorithm, which adopt derivative information of link flow with respect to design parameter, or congestion toll. Two example networks are used for test of the model proposed in the paper.