Review of evaluating existing capacity of weaving segments

Numerous studies have been conducted on freeway weaving sections, and most of these have been efforts to improve procedures in the Highway Capacity Manual. Many of these have produced models for predicting vehicle travel speeds within weaving sections. This paper reviews the previous researches about estimation of the capacity freeway weaving segment. Previous researches on weaving areas have focused on many factors that impact the capacity of freeway weaving section, which were found to include the length of the weaving section, the weaving ratio, the percentage of heavy vehicles in traffic stream, driver characteristics, lane widths, lateral obstructions, speed limit differential between freeway and onramp and offramp, geometric configuration, number of lanes in weaving section and even percentage of contribution of the four traffic movements. The Highway Capacity Manual 2000 provides values for capacity on various weaving segments (Exhibit 248) based on sets of conditions (configuration, speed, length, volume ratio, and number of lanes). However, to find capacity for a given set of conditions, an iterative process should be carried out using a properly programmed spreadsheet. This paper presents comparison among these factors and selects the most effective factor that influences in weaving section and closed the reality. Finally the results of study are compared to Highway Capacity Manual 2000 and even it presents shortcoming and overestimate of HCM.