• Journal of Korean Society of Transportation
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• v.28 no.5
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• pp.141-153
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• 2010

The study is about the development of operating speed prediction models aimed for an evaluation of design consistency of four lane rural roads. The main differences of this study relative to previous research are the method of data collection and classification of road alignments. The previous studies collected speed data at several points in the horizontal curve and approaching tangent. This method of collection is based on the assumption that acceleration and deceleration only occurs at horizontal tangents and the speed is kept constant at horizontal curves. However, this assumption leads to an unreliable speed estimation, so drivers' behavior is not well represented. Contrary to the previous approach, speed data were collected with one and data analysis using a speed profile is made for data selection before building final models. A total of six speed prediction models were made according to the combination of horizontal and vertical alignments. The study predicts that the speed data analysis and selection for model building employed in this study can improve the prediction accuracy of models and be useful to analyze drivers' speed behavior in a more detailed way. Furthermore, it is expected that the operating speed prediction models can help complement the current design-speed-based guidelines, so more benefits to drivers as real road users, rather than engineers or decision makers, can be achieved.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.8 no.2
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• pp.41-55
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• 2005

In an effort to preserve biodiversity in increasingly fragmented green patches, Korea has been installing eco-corridors over or under some arterial or expressways. In a survey of 43 such eco-corridors installed up until the year 2003, some problems and issues were identified. Some selected overseas eco-corridors were also investigated to find implications for the improvements of future installations in Korea. Major findings are; - For most existing eco-corridors, target species are not specified and locations of the eco-corridors are not well considered, and consequently it is questionable if wildlifes are crossing them - Most of existing eco-corridors lack supporting facilities such as fences that guide wildlife to cross them and prevent them from running into the road - Planting on the eco-corridors is not sufficient, not diverse enough in species, and not very considerate of wildlife but designed and planted in a similar manner as in urban parks - Where target species are not well specified, the location, width, cross section, and other aspects of the eco-corridors can not be optimized - It is suggested that eco-corridors are planned at early stages of road planning so that the number and locations of eco-corridor(s) decided as necessary and even the alignment and design of roads consider the installation of eco-corridors in advance - Monitoring of wildlife crossings is needed for improved eco-corridor planning and design - Nationwide green network plan is desirable to be made first and eco-corridors fit into it.

• International Journal of Highway Engineering
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• v.16 no.6
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• pp.169-179
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• 2014

PURPOSES : This study is to conduct the research on the design principle for the driver's safety and comfort in installing consecutive curves of superhighway. METHODS : Superhighway does not currently exist in domestic area. Thus, this study is conducted by collecting driving behavior usage of 30 people who are involved in the members of the virtual driving simulation. By identifying the distribution characteristics of each scenario in ANOVA & Tukey Test, the distribution are categorized into three groups. RESULTS : In the case of Group A in Section 3 (R2 entry part), lane departure exceeds the safety standard, which means to be risky condition. And then in the case of Group B and C, the lane departure values applying theoretical formula was evenly distributed compared to the proven values. CONCLUSIONS : Based on the result, the continuous curve design principles at superhighway should follow three standards as follow. First, an additional linear part needs to be inserted between two curves. Second, what if inserting the linear part is difficult, it would be better to insert a curve more than 2,000m. Third, R1/R2 ratio should not be over two. This design primarily aims to the safety of the operator. Such road alignment also meets the expectations of drivers, thus, it may help drivers to be compatible and amenable while driving continuous curve in superhighway.

• International Journal of Highway Engineering
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• v.11 no.4
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• pp.49-58
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• 2009

Current sunshine regulations of our country, focused on common houses and general construction, are failing to reflect adequately the characteristics of roads and elevated structures. Besides, researches are chiefly being conducted on a pitch between common houses and its diverse effects, neglecting clearance between a road or elevated structure and a residential area, environmental elements brought on by structures, such as sunshine difficulty, and their resultant factors Therefore, this study, focused on the sunshine environment of elevated structures adjacent to a residential district, as part of all roads and elevated structures, looked over currently used clearance adequacy level and analyzed the characteristics of structures in relation to an angle of direction. Then, clearance ratio by heights was calculated through a pitch by characteristics of a structure. With a view to minimize the sunshine difficulty that might occur in the future construction, it aims to propose the basic data needed for calculating the minimum clearance, while emphasizing the necessity for institutional alignment on structures.

• Tunnel and Underground Space
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• v.33 no.4
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• pp.209-227
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• 2023

The government continues to announce measures to revitalize smart construction technology based on BIM for productivity innovation in the construction industry. In the design phase, the goal is design automation and optimization by converging BIM Data and other advanced technologies. Accordingly, in the basic design of the Namhae Seomyeon-Yeosu Sindeok National Road Construction Project, a domestic undersea tunnel project, BIM-based design was carried out by developing tunnel design automation technology using 3D spatial information according to the tunnel design process. In order to derive the optimal alignment, more than 10,000 alignment cases were generated in 36hr using the generative design technique and a quantitative evaluation of the objective functions defined by the designer was performed. AI-based ground classification and 3D Geo Model were established to evaluate the economic feasibility and stability of the optimal alignment. AI-based ground classification has improved its precision by performing about 30 types of ground classification per borehole, and in the case of the 3D Geo Model, its utilization can be expected in that it can accumulate ground data added during construction. In the case of 3D blasting design, the optimal charge weight was derived in 5 minutes by reviewing all security objects on the project range on Dynamo, and the design result was visualized in 3D space for intuitive and convenient construction management so that it could be used directly during construction.

• Journal of Korean Society of Transportation
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• v.14 no.2
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• pp.119-136
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• 1996

The evaluation of risk level or possibility of traffic accidents is a fundamental task in reducing the dangers associated with current transportation system. However, due to the lack of data and basic researches for identifying such factors, evaluations so far have been undertaken by only the experts who can use their judgements well in this regard. Here comes the motivation this thesis to evaluate such risk level more or less in an automatic manner. The purpose of this thesis is to test the fuzzy-logic theory in evaluating the risk level of traffic accidents. In modeling the process of expert's logical inference of risk level determination, only the geometric features have been considered for the simplicity of the modeling. They are the visibility of road surface, horizontal alignment, vertical grade, diverging point, and the location of pedestrain crossing. At the same time, among some inference methods, fuzzy composition inference method has been employed as a back-bone inference mechanism. In calibration, the proposed model used four sites' data. After that, using calibrated model, six sites' risk levels have been identified. The results of the six sites' outcomes were quite similar to those of real world other than some errors caused by the enforcement of the model's output. But it seems that this kind of errors can be overcome in the future if some other factors such as driver characteristics, traffic environment, and traffic control conditions have been considered. Futhermore, the application of site's specific time series data would produce better results.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.4
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• pp.519-529
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• 2024

Vehicle toll discounts on private roads are categorized into two types: non-sunset and sunset. Sunset types refer to provisions in which all or part of a law loses its effect upon a specific legislator-set deadline. Vehicles eligible for 'sunset' discounts include cargo vehicles operating late at night and eco-friendly vehicles powered by electricity or hydrogen. Korean government has subsidized all reduced toll fees for vehicles classified as non-sunset types on private roads to operators, but no subsidies have been provided for toll reductions on sunset vehicles. The rapid increase in electric hydrogen vehicles escalates the burden of reduced toll revenue on private road operators. This study analyzed traffic volume and toll reduction data from eight private road operators nationwide as of the end of 2023 to propose the necessity and method of supporting sunset-type toll reduction subsidies. In 2022, the subsidy for non-sunset types amounted to 87.5 billion won, or 18.6 % of total traffic revenue. The toll exemption and reduction ratio under the concession agreement ranged from 4.0 % to 5.65 % of total traffic volume for each operator. Although the proportion of vehicles exempted from sunset traffic increased from 0.85 % in 2017 to 2.79 % in 2022, the reduction amount ratio reached 4.2 % (KRW 25.5 billion) of total traffic revenue in 2022. The escalating number of registered eco-friendly vehicles is gradually causing operating profit losses on private roads. In alignment with the government's policy to expand eco-friendly vehicles, it is imperative to consider including vehicles eligible for toll reductions listed under the sunset category for subsidy payments. The study established a minimum ratio for toll reduction assistance at 4.0 %, agreed upon between the road authorities and private operators. Three policy alternatives were proposed to ensure preservation of amounts exceeding this threshold for sustaining adequate toll revenue for private road operators.

• Journal of Korean Society of Transportation
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• v.36 no.1
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• pp.13-22
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• 2018

Buses, one of the representative public transportation modes, are divided into a vareity of service types according to the purpose of operation, operating distance, and management agencies. Although bus-involved crashes may cause large amount of damage due to the higher number of passengers boarded on a bus, prior research has little focused on crash severity according to bus service types. This study aims to investigate factors influencing crash severity in bus-involved crashes and to present policy implications to reduce crash severity by bus service type. To do this, bus-involved crash data from the Traffic Accident Analysis System (TAAS) during five-year period are used. Ordered probit models for three types of bus service, i.e., city bus, suburban and express buses, and charter buses, are estimated to analyze the factors of accident severity. The results show that there are significant differences of factors affecting crash severity among the types of bus services while speed and road surface influence all the types of buses. In case of local buses, time of day, roadway alignment, and installation of a traffic signal are found to be statistically significant factors. Seat belt and road class have significant effects on injury severity of the intercity and express buses. Chartered buses have time of day, driving experience, seatbelt, traffic signal, and day of week as the significant factors. The results of this study are expected to contribute to the reduction of the crash severity by each bus service type.

• Journal of Korean Society for Geospatial Information Science
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• v.20 no.2
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• pp.63-71
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• 2012

Recently, web portals have been offering georeferenced SLI(Street-Level Imagery) services, such as Google Streetview. The SLI has a distinctive strength over aerial images or vector maps because it gives us the same view as we see the real world on the street. Based on the characteristic, applicability of the SLI can be increased substantially through conflation with other spatial datasets. However, spatial inconsistency between different datasets is the main reason to decrease the quality of conflation when conflating them. Therefore, this research aims to remove the spatial inconsistency to conflate an SLI with a widely used 2D vector map. The removal of the spatial inconsistency is conducted through three sub-processes of (1) road intersection matching between the SLI trace and the road layer of the vector map for detecting CPPs(Control Point Pairs), (2) inaccurate CPPs filtering by analyzing the trend of the CPPs, and (3) local alignment using accurate CPPs. In addition, we propose an evaluation method suitable for conflation result including an SLI, and verify the effect of the removal of the spatial inconsistency.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.1
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• pp.192-207
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• 2023

Commercialization of level-4 (Lv.4) autonomous driving applications requires the definition of a safe road environment under which autonomous vehicles can operate safely. Thus, a risk assessment model is required to determine whether the operation of autonomous vehicles can provide safety to is sufficiently prepared for future real-life traffic problems. Although the risk factors of autonomous vehicles were selected and graded, the decision-making method was applied as qualitative data using a survey of experts in the field of autonomous driving due to the cause of the accident and difficulty in obtaining autonomous driving data. The fuzzy linguistic representation of decision-makers and the fuzzy analytic hierarchy process (AHP), which converts uncertainty into quantitative figures, were implemented to compensate for the AHP shortcomings of the multi-standard decision-making technique. Through the process of deriving the weights of the upper and lower attributes, the road alignment, which is a physical infrastructure, was analyzed as the most important risk factor in the operation risk of autonomous vehicles. In addition, the operation risk of autonomous vehicles was derived through the example of the risk of operating autonomous vehicles for the 5 areas to be evaluated.