| Summary |
The “Taiwan Highway Capacity Manual” (THCM), published by the IOT, provides important guidance in the planning, design, and evaluation of highway capacity and level of service. The chapters in the THCM relating to the for on-ramp merging areas and off-ramp diverging areas were developed based on limited onsite data collected for the THCM, the methodology is hence unable to meet current analysis needs. The IOT is preparing to revise Chapter 5
"Freeway On-Ramp Sections" and Chapter 6 "Freeway Off-Ramp Sections" of the manual. To accomplish this task, the "Advanced Planning for Traffic Characteristics Survey of Freeway Merging and Diverging Area" was completed in 2018 and clarified the main types of on-ramp merging areas and off-ramp diverging areas. In 2019, the IOT initiated a three-year research project to analyze the most common on-ramp merging areas and off-ramp diverging
areas in Taiwan, then establish the capacity and level of service analysis methods for merging and diverging areas for both freeways and expressways. The themes for the three-year research project are: isolated on-ramp merging areas and isolated off-ramp diverging areas, non-isolated on-ramp merging areas and non-isolated off-ramp diverging areas, and expressway merging and diverging areas.
This year is the third year of the research project. The focus of this year’s work are: the classification of the capacity and service level analysis methods of the on-ramp merging areas and off-ramp diverging areas; amendments to the 5th and 6th chapters of the THCM; propose a seven-step capacity and service level analysis covering both expressways with similar operating nature as well as merging and diverging areas for expressways and freeways; lastly, analyze the results to develop capacity and service level standard references and hence improve the completeness of the applicability of the service manual. Apart from analyzing the merging and diverging areas of freeways and expressways, consideration of the on-ramp and off-ramp capacities are significant in the building of interchanges. The current project stipulates recommended capacity values for single-carriageway and dualcarriageway roads as reference for actual planning in the future. |
