고속도로의 미인지 통행시간지체 추정에 관한 연구

Abstract

Expressways mean generally high speed highways that provide for high levels of safety and efficiency with full control of access. However, expressways used to suffer from unrecognized travel time delay with increased traffic volumes and high proportions of heavy vehicles on the basic segments, because most of expressways are constructed by focusing on a few hub cities in the country and are not properly furnished linked network systems with the small cities around those hub ones. Thus, it is strongly needed to improve the traffic system with traffic characteristics-related studies at the basic expressway segments.

The purpose of this study was to collect the traffic flow characteristics(volume, spot speed, headway, occupancy, and density, etc.) at the basic segments of major expressways in the country(Gyeongbu and Namhae expressways), examine the existing speed limit at the 85th percentile travel speed, analyze unrecognized travel time delay under the conditions of the 85th percentile speed at the basic expressway segments, construct the appropriate regression models between spot speed and unrecognized travel time delay, and finally select the most appropriate model between the calculated and expected travel time delay unrecognized at the basic expressway segments.

As a result of the traffic characteristic analysis, examination of speed limit at 85th percentile speed, and modeling between spot speed and unrecognized travel time delay in expressways, the following conclusions were drawn:

ⅰ) Traffic characteristic analyses were found to show a considerable difference in the directional traffic characteristics of expressways, and also in the weekday and weekend traffic characteristics. So, it was needed to directionally establish the advanced traffic management systems/advanced traveler information systems(ATMS/ATIS) depending on the weekday and weekend traffic characteristics for improving the efficiency of expressway.

ⅱ) Travel speed analyses were also found to show a considerable difference in the direction of expressways, exceeding the existing speed limit(100km/h) in the expressways. So, it was needed to reset the speed limit at the 85th percentile travel speed characteristics and examine the unrecognized travel time delay under the conditions of the 85th percentile speed at the basic expressway segments.

ⅲ) Spot speed was found to have a highly negative correlation with unrecognized travel time delay at the basic expressway segments, showing the Linear, Logarithmic, Inverse, Quadratic, and Cubic forms with the high determination coefficients () of 0.852 or higher. So, it was needed to determine the most appropriate models with correlation analysis and matched pairs sample t-Test.

ⅳ) Correlation analysis was found to show the highly positive correlation coefficients () of 0.929 to 0.985, and matched pairs sample t-Test was especially found to fall inside the Accept or Reject regions at the 95 percent confidence level depending on the models. So, it was needed to select the models falling inside the Accept region by matched pairs sample t-Test.

ⅴ) Quadratic model was found to show a high explanatory power and validity in predicting unrecognized travel time delay, having a highly positive correlation coefficients() at correlation analysis and also falling inside the Accept region at matched pairs sample t-Test for a week and weekday. So, it was needed to select quadratic model as the most appropriate one for predicting unrecognized travel time delay in expressways.