• Spatial Information Research
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• v.22 no.2
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• pp.89-97
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• 2014

This study investigated how much the spread of traffic control information affect the traffic congestion in order to identify the behavior of the individual drivers that impacts on the entire transport system. For this purpose, agent-based transportation model was constructed. GIS data were directly used for the transportation model and the processing steps of the simulation results are presented. The results showed that the average speed was not lowered when the traffic information was provided to 30 to 70% of total drivers. In contrast, the driver's average speed is reduced when he traffic information was provided to less than 20% or 80% or more. In summary, the provision of traffic information to drivers has an influence on the traffic flow and bypassing vehicles can generate local congestion. This results can be used as a basis for the future direction of road transport policy.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.6
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• pp.12-20
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• 2008

Recent wireless communication technologies are envisioned as an innovative alternative to solve transportation problems. On ad hoc networks, as a wireless communication technology, nodes can communicate data without any infrastructure. In particular, vehicular ad hoc networks (VANETs), a specific ad hoc network applied to vehicles, enable vehicles equipped with a communication device to form decentralized traffic information systems in which vehicles share traffic information they experienced. This study investigated traffic information dissemination in a VANET-based traffic information system. For this study, an integrated transportation and communications simulation framework was developed, and experiments were conducted with real highway networks and traffic demands. The results showed that it took 3 minutes in the low traffic density situations (10 vehicle/lane.km) and 43 seconds in the high traffic density condition (40 vehicle/lane.km) to deliver traffic information of 5km away with 10% market penetration rate. In uncongested traffic conditions, information seems to be disseminated via equipped vehicles in the opposite direction. In congested traffic conditions, the sufficient availability of equipped vehicles traveling in the same direction reduces the chance to use vehicles in the opposing direction even though it is still possible.

• Journal of Korean Society of Transportation
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• v.19 no.3
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• pp.115-131
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• 2001

The Purpose of this study is to develop a simulation model for large-scale network with interrupted flow as well as uninterrupted flow. The Cell Transmission(CT) theory is used to simulate traffic flow. Flow transition rules have been newly developed to simulate traffic flows at merging and diverging sections, and signalized intersections. In the model, it is assumed that dynamic OD table is exogenously given. Simulation results for toy network shows that the model can explain queue dynamics not only in signalized intersections of urban arterials, but also in merging and diverging sections of freeway. In case study, the model successfully simulated traffic flows of 145,000 vehicles on CBD network of city of Seoul with 74 traffic zones, 133 signalized intersections among 395 nodes and 1110 links.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.4
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• pp.1-12
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• 2010

This paper deals with the transmission interval of vehicle data in smart highway where WAVE (Wireless Access for Vehicular Environments) systems have been installed for advanced road infrastructure. The vehicle data could be collected at every second, which is containing location information of the vehicle as well the vehicle speed, RPM, fuel consuming and safety data. The safety data such as DTC code, can be collected through OBD-II. These vehicle data can be used for valuable contents for processing and providing traffic information. In this paper, we propose a model to decide the collection interval of vehicle information in real time environment. This model can change the transmission interval along with special and time-variant traffic condition based on the 32 scenarios using microscopic traffic simulator, VISSIM. We have reviewed the transmission interval, communication transmission quantity and communication interval, tried to confirm about communication possibility and BPS, etc for each scenario. As results, in 2-lane from 1km highway segment, most appropriate transmission interval is 2 times over spatial basic segment considering to communication specification. In the future, if a variety of wireless technologies on the road is introduced, this paper considering not only traffic condition but also wireless network specification will be utilized the high value.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.2
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• pp.9-21
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• 2011

The ramp metering strategy is one of the effective ways to solve the freeway traffic congestion in peak time periods. The study was initiated with assurance that the traffic conditions of ramp and mainline that mitigate the congestion would exist. Under the moderate traffic volume levels, ramp metering is expected to improve the quality of freeway operation. To derive a range of traffic condition, three operation strategies(Do nothing, ramp metering, minimum ramp control) were set up and the ALINEA algorithm was implemented with microscopic traffic simulator "VISSIM". The volumes of mainline and ramp are key parameters for the simulation scenarios. Measures of effectiveness for the study include mainline density and average vehicle speed. Operation boundaries in terms of traffic volume were proposed for operating ramp metering strategy. The results show that under the proposed traffic conditions the ramp metering was more successful to increase average vehicle speeds. Traffic controls under the operation boundaries of traffic levels give significant effects for density and average vehicle speed. The outcomes of this study would be useful to improve the performance of ramp metering strategies.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.2
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• pp.303-310
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• 2018

One of most shocking headlines is a serious chain collision accident (CCA). The development of CCA has a temporal and spatial locality, and the information of the CCA is time-critical. Due to these characteristics of CCA, traffic accident information should be rapidly propagated to drivers in order to reduce chain collisions, right after the first accident occurs. Inter-vehicle communication (IVC) based on ad-hoc communication is one of promising alternatives for locally urgent information propagation. Despite this potential of IVC, research for the effects of IVC on the reduction of CCA has not been reported so far. Therefore, this study develops the parallel platform of microscopic vehicle and IVC communication simulators and then analyses the effects of IVC on the reduction of the second collision related to a series of vehicles. To demonstrate the potential of the IVC-based propagation of urgent traffic accident information for the reduction of CCA, the reduction of approaching-vehicle speed, the propagation speed of accident information, and then the reduction of CCA were analysed, respectively, according to scenarios of combination of market rates and traffic volumes. The analysis results showed that CCA can be effectively reduced to 40~60% and 80~82% at the penetration rates of 10% and 50%, respectively.