• Journal of Korean Society of Transportation
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• v.28 no.6
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• pp.75-84
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• 2010

Controlled traffic intersection is critical point in terms of transportation network performance, where the most of traffic congestion arises. One of the most important and favorable measure of effectiveness in the signal controlled intersection is approach delay. Although lots of efforts to develop traffic delay estimation models have been made throughout the years, most of them were focusing on homogeneous traffic flow. The purpose of this research is to develop a traffic delay estimation model for traffic flow mixed with bus based on the horizontal shockwave theory. Traffic simulation is performed to test the adaptation level of the model in generic environment. The result shows that the delay increases with increasing bus traffic. Overall model accuracy comparing simulation result is acceptable, that shows the error range around 10 percent.

• Journal of Korean Society of Transportation
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• v.31 no.4
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• pp.3-17
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• 2013

The purpose of this study is to develop a traffic assignment model where the variable of signal intersection delay is taken into account in assigning traffic in large-scale network settings. Indeed, despite the fact that the majority of the increase in travel time or cost involving congested urban network or interrupted flow are accounted for by stop delays or congested delays at signal intersections, the existing traffic assignment models did not reflect this. The traffic assignment model considering intersection delays presented in this study was built based on the existing traffic assignment models, which were added to by the analysis technique for the computation of intersection delay provided in Korea Highway Capacity Manual. We can conclude that a multiple variety of simulation tests prove that this model can be applied to real network settings. Accordingly, this model shows the possibility of utilizing a model considering intersection delay for traffic policy decisions through analysis of effects of changes in traffic facilities on large urban areas.

• Journal of Korean Society of Transportation
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• v.19 no.1
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• pp.115-129
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• 2001

The purpose of this study is to develop a cycle-free signal timing model for minimizing delays based on Third-generation control concept using Genetic Algorithm. A special feature of this model is its ability to manage delays of turning movements on the cycle basis. The model produces a cycle-free based signal timing(cycles and green times) for each intersection to minimize delays of turning movements on the cycle basis. The performance of cycle-free signal timings was evaluated on normal (v/c = 0.7) and oversaturated (v/c=1.0) conditions. The performance measures are throughput and the number of queued vehicles at the end of green time. The result shows that the cycle free signal timing is superior to the fixed signal timing to manage traffic flows of intersections; (1) the proposed model accomplishes the basic objective of the research, producing cycle free signal timings on the cycle basis, (2) on normal conditions, cycle free signal timings produce less queued vehicles at the end of green time, and (3) on oversaturated conditions, the cycle free signal timing is superior to the fixed signal timing to manage saturated traffic flows of intersections.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.2
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• pp.269-281
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• 2018

Unlike its archetype predecessor such as the Highway Capacity Manual of the United States, the Korean Highway Capacity Manual of 2013 provides the analytical models for estimating the saturation flow rates for the lane-occupying work-zones in the proximity of the signalized intersections. Direct application of the revised saturation flow rates into the classic control delay models, however, appears to produce unreasonable delay amount as traffic demand approaches lane-group capacities and surpasses them, which is common phenomena in the work-zones. Complex interaction among vehicles, lane-dropping work-zone geometry and signal operations were never accounted in the traditional control delay models, and considerable differences between the delay model outcomes and field observations are repeatedly experienced. This paper proposes the modified approaches to the delay models in the manual, exerted on all three elements of control delay, and particularly focuses on the temporal and spatial boundary expansion in comparing the simulated results to the estimated ones. Extensive microscopic simulation work and calibration effort supports the modified approaches well enough to use them in the work-zone planning and evaluation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.2
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• pp.283-294
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• 2018

An accurate pedestrian-delay model is essential for the pedestrian-oriented evaluation of signalized intersection (SI). The crossing behaviors of pedestrians at signalized pedestrian crosswalks (SPCs) are various, and their arrival behaviors consist of two types, random and platoon. It is natural, hence, that the behaviors of pedestrian crossing and arrival should be considered in order to estimate accurate pedestrian delay. Despite this necessity, a simple pedestrian-delay model that cannot explain these behaviors of pedestrian movements is still recommended in Highway Capacity Manual (HCM). For these reasons, a pedestrian-delay model, suitable for various SPCs and SIs, is required to make pedestrian-oriented decisions on the design and operation of various SPCs and SIs. This paper proposes a novel pedestrian-delay model that is based on the behaviors of pedestrian crossing and arrival. The proposed model consists of two sub models: the one for SPC and the other for SI. The SPC delay model was developed based on the behaviors of pedestrian crossing during pedestrian green time. The SI delay model was designed based on the behaviors of pedestrian crossing and platoon arrival. The results of a numerical simulation showed that the proposed delay model can successfully overcome the under- and overestimation problems of the HCM model with explaining various behaviors of pedestrian crossing and arrival.

• Journal of Korean Society of Transportation
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• v.28 no.6
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• pp.65-74
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• 2010

This study aims at developing a method for estimating passenger car equivalency (PCE) values for various vehicle types that could be considered in estimating capacity and delay at intersections without traffic signals, especially at modern small 3-leg roundabouts. Unlike signalized intersections, the PCE value has not yet been treated explicitly in traffic operations involving unsignalized intersections. Both empirical and theoretical approaches for determining the PCE values at modern small 3-leg roundabouts were evaluated. As a result, the PCEs derived in this study were highly correlated with those of field measurements.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.4
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• pp.897-905
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• 2015

This research suggested the traffic signal calculation model of active transit signal priority using a shockwave model. Using this signal priority timing optimization model, the shockwave area is computed under the condition of Early Green and Green Extension among active transit signal priority techniques. This study suggested the speed estimation method of backward shockwave using average travel time and intersection passing time. A shockwave area change is calculated according to signal timing change of transit signal priority. Moreover, this signal timing calculation model could determine the optimal signal priority timings to minimize intersection delay of general vehicles. A micro simulation analysis using VISSIM and its user application model ComInterface was applied. This study checked that this model could calculate the signal timings to minimize intersection delay considering saturation condition of traffic flow. In case studies using an isolated intersection, this study checked that this model could improve general vehicle delay of more over ten percentage as compared with equality reduction strategy of non-priority phases. Recently, transit priority facilities are spreading such as tram, BRT and median bus lane in Korea. This research has an important significance in that the proposed priority model is a new methodology that improve operation efficiency of signal intersection.

• Journal of Korean Society of Transportation
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• v.15 no.2
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• pp.105-122
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• 1997

본 연구는 대각선 횡단보도의 정량적 설치기준을 정립하기 위하여 이상적인 조건에서의 교차로 각현시별 임계차선 교통량의 합($\sum_i$ CVi)을 600~1,800대로 변화를 주어 실험적 시뮬레이션 방법을 적용하였다. TRANSTY-7F 모형을 이용한 교차로 평균차량 지체도와 본 연구에서 정립한 보행지체모형을 이용한 교차로 평균 보행지체도와의 관계를 변수로 하여 대각선 횡단보도의 정량적 설치기준을 각 조건별로 산정한 결과 다음과 같은 결론이 도출되었다. 첫째, 동시신호시 교통량과 보행량의 비율이 1:1일 경우 대각횡단비율 20~40%에서는 $\sum_i$ CVi=1,050~1,150대 이하에서 대각선 횡단보도를 설치시 지체도 감소에 대한 편익을 얻을 수 있다. 둘째, 동시신호시 교통량과 보행량의 비율이 1:2일 경우 대각횡단비율 20~40%에서는 $\sum_i$ CVi=1,150~1,200대 이하에서 대각선 횡단보도를 설치시 지체도 감소에 대한 편익을 얻을 수 있다. 셋째, 선행 좌회전신호시 교통량과 보행량의 비율이 1:1일 경우 대각횡단비율 20~40%에서는 $\sum_i$ CVi=600~750대 이하에서 대각선 횡단보도를 설치시 지체도 감소에 대한 편익을 얻을 수 있다. 넷째, 선행 좌회전신호시 교통량과 보행량의 비율이 1:2일 겨우 대각횡단비율 20~40%에서는 $\sum_i$ CVi=750~900대 이하에서 대각선 횡단보도를 설치시 지체도 감소에 대한 편익을 얻을 수 있다.

• Journal of Korean Society of Transportation
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• v.27 no.2
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• pp.199-206
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• 2009

In relation with economical efficiency analysis on investment evaluation of transportation system, among vehicle operating cost saving benefit that is applied to general preliminary assessment guidelines and investment evaluation guidelines, oil expense calculated data which concentrated and analyze on the relationship between oil consumption amount on running state and running speed. For uninterrupted flow which does not have stopped delay due to traffic signal, consideration for reduction benefit is possible due to the changes of running speed and travel time however, for interrupted flow which the stopping occurs due to signal control on actual signal intersection has no consideration for stopping delay time reduction and stopping rate improvement thus reflection of reality on improved effect analysis is difficult. Therefore, this research makes a framework to analyze benefits that reflects the features of signalized intersections by benefits associated with decrease of stopping delay time with existing research and developing vehicle operating cost calculation model formula. Vehicle operating cost has been redefined considering the stopping delay time by applying the oil consumption amount at idling and the economical benefit between conventional model and newly developed model when applied for the optimization of traffic signal system on the two roads in Seosan city has been analyzed comparative. While the importance of traffic system maintenance is being emphasized due to the increase of congested areas on roads, it is expected to assist in more realistic economical analysis which reflect the delay improvement through the presentation of an economic analysis model that considers the features of signalized intersections in signal optimization system improvements and effect analysis of congestion improvement projects`.

• Journal of Korean Society of Transportation
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• v.26 no.3
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• pp.169-178
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• 2008

Level of Service (LOS) is one of ways to evaluate operational conditions. It is very important factor in evaluation especially for the facility of highways. However, some studies proved that ${\upsilon}/c$ ratio and accident rate is appeared like a second function which has a U-form. It means there is a gap between LOS and safety of highway facilities. Therefore, this study presents a method for evaluation of a signalized intersection which is considered both smooth traffic operation (delay) and traffic safety (accident). Firstly, as a result of our research, accident rates and EPDO are decreased when it has a big delay. In that reason, it is necessary to make a new Level of Service included traffic safety. Secondly, this study has developed a negative binominal regression model which is based on the relation between accident patterns and stream. Thirdly, standards of LOS are presented which is originated from calculation between annual delay costs and annual accident cost at each intersection. Lastly, worksheet form is presented as an expression to an estimation step of a signalized intersection with traffic accident prediction model and new LOS.