Generally, density is used as a measure of effectiveness (MOE) of the level of service for the basic segment of the roadway facility, but can not express the operational condition of the roadway facility properly because there is an error in the computed density compared with the density measured in the field. Thus, the purpose of this study is to investigate the real-time traffic characteristics (traffic flow, speed, occupancy, headway, spacing, etc.) observed from the detectors installed on the mainline section of urban freeway under the study, compute the maximum flow rate from the relationship between the real-time traffic characteristics observed, and evaluate the level of service (LOS) of the mainline section of urban based on the relationship between the occupancy and the v/c ratio depending on the level of service (LOS).
From the traffic characteristic analyses, and the LOS analysis and evaluation of the traffic characteristics in the mainline section of urban freeway, the following conclusions were drawn ⅰ) There was a considerable difference in the directional and lane-based traffic characteristics of urban freeway. Particularly, the maximum service flow rates in the inbound direction were shown to be more than those in the outbound direction by about 6%, and the maximum service flow rates on the lane 1 were more than those on the lane 2 by about 18%,
ⅱ) The free flow speed (FFS) in the inbound direction was shown to be lower than the FFS in the outbound direction by about 10%, and also the FFS on the lane 1 higher than the FFS on the lane 2 of urban freeway by about 20%,
ⅲ) The maximum occupancy in the inbound direction was shown to be about 18% and that in the outbound direction shown to be about 14% at the LOS E, and it was shown to be the LOS A≤2%, the LOS B≤3%, the LOS C≤6%, the LOS D≤8%, the LOS E≤18%, and the LOS F>18% in the maximum occupancies for each LOS.
It was concluded that this study could be needed to be continued with the expressway or the highway for the purpose of the LOS evaluation by the occupancy instead of the density.