• Journal of Korean Society of Transportation
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• v.26 no.5
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• pp.175-184
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• 2008

Uncertainties are unavoidable in engineering applications. In this paper we propose an alpha reliable multi-variable network design problem under demand uncertainty. In order to decide the optimal capacity enhancement, three performance measures based on 3E(Efficiency, Equity, and Environmental) are considered. The objective is to minimize the total budget required to satisfy alpha reliability constraint of total travel time, equity ratio, and total emission, while considering the route choice behavior of network users. The problem is formulated as the chance-constrained model for application of alpha confidence level and solved as a lexicographic optimization problem to consider the multi-variable. A simulation-based genetic algorithm procedure is developed to solve this complex network design problem(NDP). A simple numerical example ispresented to illustrate the features of the proposed NDP model.

• Journal of Korean Society of Transportation
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• v.19 no.5
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• pp.143-154
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• 2001

신호교차로의 서비스수준은 미국의 HCM 방식을 전세계적으로 준용하고 있으며, 우리나라도 1985년 미국 HCM을 기본으로 하여 우리나라의 특성을 반영한 보정계수 값들을 수정하여 지금까지 사용하고 있는 것이 현실이다. 하지만 한국 도로용량편람의 모태가 된 미국 HCM은 이미 94년 1차 수정판에 이어, 이를 더욱 보완해서 HCM 2000을 발간하여 실용화 단계에 있는 반면 92년에 발간된 한국도로용량편람은 발간 이후 빠른 속도로 변화해온 국내의 교통, 도로, 차량 특성과 다양해진 도로시설 유형의 변화를 신호교차로 서비스수준 분석에 적절히 반영하지 못하고 있다. 이에 본 연구는 신호교차로 서비스수준 결정에 관한 연구의 기초작업으로 기존의 신호교차로 서비스수준 분석방법의 문제점을 보완하기 위한 새로운 분석방법론을 제시하였다. 이를 위해 한국 도로용량 편람과 미국 HCM 2000의 서비스수준 분석방법론 부분을 면밀히 비교 분석하고 두 나라의 지체식에 포함된 공통적인 변수(주기(C), 포화도(v/c), 용량(c), 녹색시간비(g/C))에 대한 민감도 분석과 미국 HCM 2000에 추가로 도입된 변수들에 대한 민감도 분석을 수행함으로서 한국 도로용량 편람의 문제점을 고찰하고 운전자의 행태나 도로의 기하조건이 외국의 경우와는 다른 우리나라 실정을 반영한 한국형 신호 교차로 서비스수준 정립 방안의 필요성을 제시하였다.

• Journal of Korean Society of Transportation
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• v.27 no.3
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• pp.141-148
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• 2009

An inappropriate evaluation of capacity leads to the incorrect and impractical result due to the transfer of error to the analysis and the evaluation on highway system. The traffic accident which reduces the capacity of road temporarily generates unpredictable congestion, causing difficulties in congestion management. Therefore, this research aims on the measurement of the capacity of the road in accordance to the speed at the accident which is a basic factor when performing analysis. Based on the given approach, the behavior of a vehicle in highway is understood to develop model of critical gap and model of maximum flow rate with respect to the speed of traffic flow. With the established model, the reduction rate of the capacity in highway system at the accident is measured. The result shows that the capacity is reduced by 37% when the speed of the traffic flow is 40km/h. Although the developed model can't be verified clearly, this research has shown that the reduction rate of the capacity in road system has a close relation to the speed.

• Journal of Korean Society of Transportation
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• v.16 no.3
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• pp.7-14
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• 1998

터널의 경우 도로교통용량이 일반구간에 비해 감소하는 것으로 나타나고 있다. 그러나 연속되는 터널의 경우에 있어 도로교통용량감소에 대한 연구는 아직 이루어지지 않고 있다. 본 연구에서는 고속도로의 2지점에서 연속되는 터널의 도로교통용량의 감소특성을 이용한 터널보정계수를 산정하여 다음과 같은 결과를 도출하였다. (1) 터널을 통과하는 경우의 도로교통용량은 통과전보다 감소하는 것을 알 수 있으며, 연속되는 터널을 통과하는 경우 감소량은 이보다 큰 것으로 나타났다. (2) 터널보정계수$(f_{tu})$를 도출한 결과 하나의 터널을 통과하는 경우의 터널보정계수$(f_{tu1})$는 0.95, 연속되는 터널을 통과하는 경우의 터널보정 계수$(f_{tu2})$는 0.90으로 산정되었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2D
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• pp.251-258
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• 2006

This study is to develop an estimation method of freeway design capacity through the analysis of time headway distribution in continuum flow. Traffic flow-speed diagram and time headway distribution plotted from individual vehicle data shows: a) a road capacity is not deterministic but stochastic, b) time headway distribution for each vehicle speed group follows pearson type V distribution. The freeway design capacity estimation model is developed by determining a minimum time headway for capacity with stochastic method. The estimated capacity values for each design speed are lower when design speed ${\leq}80km/h$, and higher when design speed ${\geq}106km/h$ in comparison with HCM(2000)'s values. In addition, The distinguish difference is that this model leads flexible application in planning level by defining the capacity as stochastic distribution. In detail, this model could prevent a disutility to add a lane for only one excess demand in a road planning level.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.2
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• pp.48-61
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• 2020

The objective of this study is to estimate traffic capacity based on the heavy-vehicle ratio in a two-lane freeway work zone where one lane is blocked by construction. For this, closed circuit television (CCTV) video data of the freeway work zone was collected, and the congestion at an upstream point was observed. The traffic volume at a downstream point was analyzed after a bottleneck was created by the blockage due to the upstream congestion. A distribution model was estimated using observed-time headway, and the road capacity was analyzed using a goodness-of-fit test. Through this process, the general capacity and an equation for capacity based on the heavy-vehicle ratio passing through the work zone were presented. Capacity was estimated to be 1,181~1,422 passenger cars per hour per lane (pcphpl) at Yeongdong, and 1,475~1,589pcphpl at Jungbu Naeryuk. As the ratio of heavy vehicles increased, capacity gradually decreased. These findings can contribute to the proper capacity estimation and efficient traffic operation and management for two-lane freeway work zones that block one lane due to a work zone.

• Journal of Navigation and Port Research
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• v.31 no.1 s.117
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• pp.107-113
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• 2007

This research addressed the problem of describing how the operating characteristics of passenger car and large vehicle differ qualitatively and quantitatively through the analysis of field survey data. A formulation that estimates passenger car equivalents used in this paper is derived by microscopic headway method. Regression analysis was used to focus on the effect of vehicle type on intervehicular spacings and the modeling technique for the statistical analysis was detailed.

• Journal of Korean Society of Transportation
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• v.24 no.1 s.87
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• pp.7-18
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• 2006

Nowadays, the movement of commercial vehicles has caused severe congestion, environmental problems and damaged pavements in urban area. To solve the Problems, this research has proposed a methodology to build-up a freight network that is enable to manage the movement and demand of commercial vehicles. The network based on urban arterial network has developed according to freight traffic volume that is under the influence of road types among The in study area. Freight network has been developed by assignment method of 4-step transportation forecasting. Once, acceptable limits of freight traffic volume are decided, freight network can be developed using the capacity To confirm the application of the methodology, freight network of Seoul city has developed by the methodology.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.10
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• pp.327-330
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• 2016

In the road environment with lots of vehicles, we can increase the number of vehicles on the road (i.e., road capacity) and enhance the comfortability of drivers if vehicles are organized into platoons. In the traditional vehicle platooning mechanisms, a pre-determined set of vehicles are allowed to form a platoon and, among them, a specific vehicle is designated as the platoon leader. In this type of platoon mechanisms, platoon is limited in improving the road capacity because the vehicles allowed to involve into platooning are restricted. Therefore, in this paper, we propose an adaptive platoon formation mechanism that allows any vehicle to be a platoon leader from which a platoon is formed. In the proposed mechanism, a platoon leader is elected based on the relative velocity and location information of neighboring vehicles obtained through the periodic exchange of beacon messages among vehicles. Through the NS-3 based simulations, we show the performance of our proposed mechanism in terms of road capacity improvement.

• Journal of Korean Society of Transportation
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• v.30 no.1
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• pp.75-83
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• 2012

This study is to find a shortcoming embedded in the current Korean Highway Capacity Manual (KHCM) on reflecting a heavy vehicle effect to the highway capacity. The KHCM suggests to handle the percent heavy vehicle to deal with its effect to a capacity regardless of density levels. Authors hypothesized in this study that the effect of heavy vehicles would vary at different levels of traffic density - the effect would be comparably insignificant when a density is low and it becomes comparably significant when it becomes high. Field data from a freeways located in Seoul were collected for 360 hours (15 days) and categorized them into a set of operation conditions grouped by 15 minutes and by the LOS density levels. Comparison between the field measured and the estimated by the KHCM method showed that the KHCM method overestimated the effect of heavy vehicles in LOS B and C but underestimated in LOS E. The results suggested that there be a difference pattern from the one the KHCM expected and brought discussion on further studies.