• International Journal of Highway Engineering
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• v.14 no.6
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• pp.75-84
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• 2012

PURPOSES : This paper aims to improve the evaluation method of the Level of Service(LOS) for urban streets presented by the current Korean Highway Capacity Manual(KHCM) and suggest its utilization plan as a part of the methods to evaluate the sustainability of a transportation policy. METHODS : This paper carried out a research in 3 steps to develop a new evaluation method. First of all, this paper reviewed the previous studies related to the LOS of urban streets and the socially requested items for a sustainable transportation system. Then this paper derived an index and weight through expert questions to select an evaluation index. Lastly, this paper compared the results according to the existing evaluation methods with the new evaluation methods through case studies. This paper used an Analytic Hierarchy Process(AHP) for importance analysis and weight selection between new evaluation items and indices, and applied a Grey System Theory(GST) for a synthetic and integrated evaluation between the selected evaluation indices. RESULTS : As a result of evaluating the LOS according to the existing evaluation methods and the integrated evaluation methods using a GST through case studies, it was analyzed that new methods' results are less than or equal to the existing evaluation methods; and as a result of applying a weight between evaluation indices according to AHP, it was noticed that the total score seems to rise more when the LOS in the existing evaluation is calculated lower. It was analyzed that the LOS calculated by reflecting the newly established evaluation items and the importance between indices in this study has difference from the LOS of the existing urban streets. CONCLUSIONS : It is expected that this evaluation method can diagnose the current conditions when establishing a future sustainable traffic system and can be used for the measurement of the sustainability effects of the improvement plans and so on.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3D
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• pp.215-222
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• 2010

Average speed denotes a travel speed based on the average travel time of vehicles to traverse a segment of roadway, and average travel speed is used as a measure of effectiveness (MOE) suggested in the highway capacity manual (HCM) for evaluating the level of service (LOS) of roadway. Most of the urban freeways in our country are having congestion problem regardless of the rush hours as a high-speed highway with a speed limit of 80km/h or less. Especially traffic congestion within the ramp junction areas is becoming worse by the increased traffic and lack of links with the arterials around the urban freeway. So, the purpose in this study is to identify the traffic characteristics within the ramp junction areas of urban freeway, predict the average speed within the ramp junction areas based on the traffic characteristics identified, and finally prove the validity of the average speed predicted.

• International Journal of Highway Engineering
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• v.18 no.4
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• pp.77-82
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• 2016

PURPOSES : This paper proposes a reliability index for the safety evaluation of freeway sections. It establishes a reliability index as a safety surrogate on freeways considering speeds and speed dispersions. METHODS : We collated values of design elements including radii, curve lengths, vertical slopes (absolute values), superelevations, and vertical slopes from seven freeway sections in Korea. We also collected data about driving speeds, traffic accidents, and their deviations. We established a reliability index using these variables. RESULTS : The average radii, curve lengths, and superelevations are highly correlated with the incidence of traffic accidents. Deviations in radius and curve lengths show an especially high correlation. The reliability index, derived from speed and speed dispersions of the seven freeway sections, also correlated highly with accidents with a correlation index of 0.63. CONCLUSIONS : Since the reliability index obtained from speed and speed dispersions are highly correlated with traffic accidents, we conclude that a reliability index can be a safety surrogate on freeways considering speeds and speed dispersions together in terms of design and operational levels.

• International Journal of Aeronautical and Space Sciences
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• v.8 no.2
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• pp.54-66
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• 2007

Traffic and emergency monitoring systems are essential constituents of Intelligent Transportation System (ITS) technologies, but the lack of traffic monitoring has become a primary weakness in providing prompt emergency services. Demonstrated in numerous military applications, unmanned aerial vehicles (UAVs) have great potentials as a part of ITS infrastructure for providing quick and real-time aerial video images of large surface area to the ground. Despite of obvious advantages of UAVs for traffic monitoring and many other civil applications, it is rare to encounter success stories of UAVs in civil application including transportation. The objective of this paper is to report the outcomes of research supported by the state agency in US to investigate the feasibility of integrating UAVs into urban highway traffic monitoring as a part of ITS infrastructure. These include current technical and regulatory issues, and possible suggestions for a future UAV system in civil applications.

• Journal of Korean Society of Transportation
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• v.13 no.1
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• pp.125-152
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• 1995

The purposes of this study are twofold ; (1) to investigate the accuracy of estimation power of the individual models. such as those of Highway Capacity Nanual (HCM), Korea Highway Capacity Manual (KHCM), and NationalCooperative Highway Research Program(NCHRP) Report339 ; and (2) to develop an adjusted delay model which can be applied to the signal control system in urban areas. The study is mainly focused on four subjects related to the research purposes, which are as follows ; (1) characteristecs of exsisting delay models ; (2) inherent problems in exsisting delay models : (3) validation of the proposed model by the comparison of observed delay with estimated delay :and (4) a method which can be applied to develop an appropriate delay model for actrual signal control systems by the adjusted fact of the proposed model.

• Land and Housing Review
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• v.11 no.4
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• pp.115-124
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• 2020

Incentive/Disincentive (I/D) contract is designed for minimizing any disruption of traffic flow in road construction projects. I/D contracting projects have been evaluated with regard to time and cost performance in various states, more than 35 states. However, construction project managers and planners have little understanding of the project factors that affect the project time and cost performance of highway construction projects using I/D regulations. Therefore, the purpose of this research is to find factors that affect I/D project success or failure to improve the decision-making process for the implementation of I/D projects. In order to achieve the objectives of this research, the researchers collected I/D road construction project data from FDOT and performed evaluation for each collected project. Then, project data analysis to identify key factors that affect I/D project performance was performed. In conclusion, five significant factors for project time performance and six significant factors for project cost perfornace were identified and summarized.

• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.849-856
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• 2020

Purpose: Greenhouse gases are one of the major causes of global warming, a global disaster. It aims to improve how effective the GHG reduction policy, which is the main cause of global warming in the transportation sector, has been effective on the highway and how to calculate GHG emissions. Method: Using the DSRC raw data, we estimate the emissions of Namhae Expressway (Yeongam-Suncheon) from 2017 to 2019 in two ways, a macro method (conventional) and a micro method (individual vehicle). Result: As a result of calculating the emission of the highway, the result was far exceeding the estimated emission, and it was found that when the calculation was performed for each vehicle, it was underestimated by more than 20%. Conclusion: If more emissions are continuously emitted than expected in the current transportation sector, additional emission reduction policies are needed to achieve the current greenhouse gas reduction targets. In addition, in the calculation of emissions, which is the basis of this policy, analysis was conducted for each individual vehicle using the current DSRC raw data, but using GPS afterwards will enable precise emission calculation through a more microscopic analysis.

• Ecology and Resilient Infrastructure
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• v.3 no.4
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• pp.272-278
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• 2016

Porous pavements are recommended as a Low-Impact Development (LID) method which is a strategy to develop a water cycle as close to a natural state as possible, and to solve the urban impervious surface problems. Porous pavements can yield a solution if it provides a more permeable surface with extra space to contain extra water from building roofs. But there are few applications in Korea because of a lack of recognition and experience. Highway engineers are mainly concerned about the infiltration of water into pavement structures. They worry about the weakening of the asphalt mixture and subgrade, and freezing during the winter season due to the infiltration of water. Meanwhile, hydrological experts doubt the effects of the amount of water to control during the flooding season, and environmental experts prefer a non-point pollution treatment system established beside highway. In this study, from reviewing the history and the body of literature about porous pavements, conclusions regarding the most advanced technologies were made. First, traditional thickness designs can be used for porous pavement, no extra distresses was found by weakening and freezing during the winter season. Second, hydrological design can be made by controlling the thickness of the pavement and the outlet of water. Third, the treatment efficiency of non-point pollution of porous pavements is not worse than any other method. Importantly, it's a more eco-friendly solution because of its lower requirement for de-icing agents.

• Journal of Korean Society of Transportation
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• v.14 no.2
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• pp.223-237
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• 1996

Based on the traffic and accident data collected on a 4.2km (2.6mile) section of Interstate highway 35W in Minneapolis the relationship between traffic operation variables and safety measures is investigated. An aggregate specification that could be integrated into an urban freeway safety prediction methodology is proposed as a multiple regression model. The specification includes lane occupancy and volume data, which are the control parameters commonly used because they can be measured in real time. The primary variables that appear to affect the safety of urban freeway are : vehicle-miles of travel, entrance ramp volumes and the dynamic effect of queue building. The potential benefits of freeway traffic control strategies on freeway safety are also investigated via a simulation study. It was concluded that improvement of urban freeway safety is achievable by traffic control strategies which homogenize traffic conditions areound critical occupancy values.

• 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.