• Journal of Korean Society of Transportation
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• v.33 no.1
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• pp.81-89
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• 2015

Crashes that occur at tollgates have different characteristics compared to those of the mainline on expressways in terms of crash cause, crash type, and vehicle type. Due to this fact, the safety performance function (SPF) focused on the expressway tollgates, apart from the mainline, should be developed. The aim of this study is, therefore, to identify the influential factors and develope a SPF for crashes at tollgates. Firstly, we established independent variables affecting crashes at tollgates through literature review and descriptive statistical analysis. Based on these variables, two negative binomial regression models with different form of independent variables were developed and goodness-of-fits of each model were compared. According to the results, the number of crashes increases i) as AADT, Hi-pass rate, and heavy vehicle rate increase, ii) as average lane width decreases, iii) on the mainline tollgate type. The safety performance function developed in this study could be applied to select hot-spots for expressway tollgates.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.3
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• pp.102-111
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• 2012

Expresway traffic accident is fatal accident by high speed, especially human injury is a great social issue. This paper aims to identify characteristic differences of highway accidents that involve human injuries or not. To analysis the elements that affect the two types of accidents used the logistic regression model. The analysis showed that human injury accident rate is increased in case of straight road, flat, or cut-slope areas, barriers, male driver, and older driver. These results provide the ground for actions to counter the problems. By discovering factors for accidents leading to fatality, this study can provide important implications for authorities that establish highway safety measures and policies in preventing human injuries or deaths from car accidents.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.2
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• pp.1-11
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• 2013

This research proposed integrated expressway traffic management strategy using ramp metering and toll mainline metering. This research suggested a traffic signal optimization model for integrated operation of ramp and mainline metering based on Demand-Capacity Model that is used to optimize allowable input volume for ramp metering in FREQ model. The objective function of this model is sectional throughput volume maximization, and this model can calculate optimal signal timings for mainline metering and ramp metering. This study conducted an effectiveness analysis of integrated metering strategy using PARAMICS and its API. It targeted Seoul's Outer Ring Expressway between Gimpo and Siheung toll gate. As a simulation result, integrated operation of mainline and ramp metering provided more smooth traffic flow, and throughput volume of mainline increased to 14% in congested section. In addition, a queue of 400 meter was formed at metering point of toll gate. This research checked that integrated traffic management strategy facilitates more efficient traffic operation of mainline and ramp from diffused traffic congestion.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.2
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• pp.67-76
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• 1992

A procedure to determine the axle load limits of asphalt concrete pavements are proposed in this study. Axle load limits are determined by calculating maximum tensile strains at the bottom of the asphalt stabilized base layer and maximum vertical strains at the top of the subgrade. In order to investigate the efficiency of axle configuration, calculated influence line of wheel load on domestic expressway pavement system is used. Limiting strains are selected through the analysis of conventional failure criteria. From the analysis of axle load limits about axle composition(single-axle, tandem-axle, tridem-axle), it is found that the axle load limits of tandem-axle and tridem-axle can be calculated by muitipling the axle load limits of single-axle by axle numbers and that axle load limits are closely related to the thickness of each layer of pavement structure. It is also found that the axle load limits by tensile strains are more critical than those by vertical strains on asphalt concrete pavement models of YOUNG-DONG, KYONG-IN and KYONG-BU expressways.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.33-40
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• 1988

In this study, effects of the density of soil and the confining pressure applied to the soil sample on the elastic moduli of subgrade soils are experimentally analyzed. Through investigation of subgrade materials of domestic expressways, five typical types of subgrade soils are selected for the experiments. A series of unconsolidated undrained triaxial tests is performed on samples prepared with various water contents and densities at the confining pressures of 1.02, 2.04, and $3.06kg/cm^2$. Initial tangent modulus is inferred from the unloading-reloading portion of the stress strain curve obtained during an individual loading-unloading-reloading test. As a result of the analysis, it is found that the effect of the confining pressure on the elastic modulus of subgrade material is well consistent with the equation proposed by Janbu, and that the elastic modulus can be related to the dry unit weight expressing the Janbu constants as exponentiial functions of it. It is also found that the water content has little effect on the elastic modulus for the samples with the degree of saturation less than 70%.

• International Journal of Highway Engineering
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• v.14 no.2
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• pp.1-10
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• 2012

As old concrete pavements of over 20years in age are increasing in expressways, the repair and rehabilitation of concrete pavement have become an important issue. Although asphalt overlay is widely used as an alternative to rehabilitate the old concrete pavement, problems due to infiltrated water such as reflection crack and pothole are imposing a very serious threat to its performance. This study proposes waterproof membrane as a solution to minimize the damage due to reflection crack and infiltrated water, and accelerated pavement testing was carried out for the performance comparison of composite pavement with waterproof membrane and ordinary tack coating. The experiment used water spraying to simulate rainfall, and the behavior and moisture resistance characteristics of overlay pavement were analyzed. The experimental result indicated that the strain pattern of waterproof membrane section differed from ordinary tack coating section because waterproof membrane caused the asphalt pavement and concrete pavement to move together. Additionally, since waterproof membrane minimized the infiltration of water and delayed the occurrence of reflection crack by about 70% in comparison to ordinary tack coating method. Moreover, the damage due to infiltrated water also decreased.

• Journal of Korean Society of Transportation
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• v.24 no.4 s.90
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• pp.19-29
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• 2006

As the rapid increase of highway investments from Private sector the organizations of highway operator became diversified, and thus causing various unexpected problems. Highways invested by private capitals have different fare rates and managing systems. It is desirable to reduce drivers' inconvenience using more than two sections of highways spread over different jurisdictions. The main purposes of this research are i) data survey and problem statements ii) prediction of future problems and preparing appropriate countermeasures. This research are divided into two parts. They are management system and fare collection system. Major investigations of this study are as follows, optimum toll operation models depend on charging systems and interchange shapes of two interconnecting expressways. Assuming that the current payment and the new electronic payment system aye used concurrently for a while, some alternatives for the inter-operation to collect tolls ate suggested focusing on the efficiency to tollway corporations as well as convenience to drivers. The advantages and disadvantages of the alternatives, including their characteristics, are compared.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.55-61
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• 2009

In order to observe the impact of a type of vehicles for traffic flows and pavement, vehicle classifications is conducted. Korean Ministry of Land, Transport and Maritime Affairs provides 12-type vehicle classifications on National expressways, National highways, and Provincial roads. Current AVC (Automatic Vehicle Classification) devices decide vehicle types comparing measurements of vehicle lengths, wheelbases, overhangs etc. to a reference table including those of all types of models. This study developed an algorithm for macroscopic vehicle classification which is less sensitive to tuning sensors and updating the reference table. For those characteristics, trend lines in vehicle lengths and wheelbases are employed. To assess the algorithm developed, vehicle lengths and wheelbases were collected from an AVC device. In this experiment, this algorithm showed the accuracy of 88.2 % compared to true values obtained from video replaying. Our efforts in this study are expected to contribute to developing devices for macroscopic vehicle classification.

• Journal of Korean Society of Transportation
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• v.27 no.6
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• pp.7-18
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• 2009

In 2008, there are 135 service areas, which provide for drivers to convenience on expressways. But there are some problems on parking capacity, because it is failed to calculate the appropriate parking lots of the service area. The fundamental problem is that the size of parking lots is calculated by simple value; despite there are various factors of utilization, congestion, and turnover. This paper describes a study on proper coefficient for calculating the appropriate service area, considering the characteristics of drivers' behavior. We conducted statistical analysis with the surveyed data in "Status of the expressway facilities in 2004." Analysis results show there are some difference by day and night, and vehicle type with the factor of utilization, congestion, and turnover, and there are different usages according to expressway route. The results indicate that the usage of a service area have different characteristics by time and space, and vehicle type.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.21 no.4
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• pp.75-86
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• 2018

This research was thereby made to study and analysis ecological, landscape, and stability qualities of roadside cut Slopes in expressways and national highways that went through revegetation works. Also, evaluation items and framework for integrated assessment of plant structure and restored state for the maintenance were suggested. Following is the summary of the result. firstly, for stabilization of introduced native plant species on roadside cut slops, assessment on the post-project environmental management through long-term monitoring and maintenance works must be made. It signifies a form of authentic recovery and restoration by the native plants. second, current evaluation framework on the test beds is well managed with clear evaluation standards and table while its method of assessing the post management with only test bed results lacks conformity with this study site. Newly developed evaluation framework on the post construction sites is estimated to be used as assessment standards on any roadside construction sites. Third, after site investigation distinction was observed among different revegetating construction types in the long-term perspective. Due to the different duration time of vegetation state between seed-spray measures(degraded in time) and layer-spray measure(maintained), the use of coarse straw-mat mulching work or Coir net was suggested in long term maintenance of cut slopes. forth, segmentation of post environmental assessment is organized into three large categories of "ecological", "stabile", and "landscape" qualities regarding post restoration quality and stability of slope through native plants with which categories marks 50, 30, 20 points of rates. fifth, components of the post environmental assessment were segmented in twelve categories driving results from former experimental construction and newly focused items on site. In the future, it is possible to propose a customized assessment method considering the location and location of construction work if the research on the application of post-environment assessment methods for road construction surface recording is conducted systematically.