Institute of Transportation, MOTC

• Date：2019-03-05
• Update：2019-03-05
• Department：IOT

Overview：

　　In 1990, according to the analysis methods of the American 1985 TRB Highway Capacity Manual “Taiwan Highway Capacity Manual” was published by this institute. Later on, its contents were amended gradually according to the research results on the localized traffic flow and the updated “Taiwan Highway Capacity Manual” was published in 2001 and 2011. In spite of this, some chapters still remain unchanged until now. The main purpose of this Plan is to update and modify the capacity analysis method for “Suburban dual-lane highway”.

Research result：

　　Described below are the reasons required for updating the analysis method established for “Chapter 12: Non-interruptive Traffic Flow Section for Suburban Dual-lane Highway” as specified in 2011 Taiwan Area Highway Capacity Manual.

• The analysis method is quoted from American 1985 TRB Highway Capacity Manual. Because the analysis method is not suitable for this edition in America, it has been replaced by the newly established analysis method.   
• Based on the terrain, the suburban dual-lane traffic is divided into Plain Area, Hill Area and Mountain Area in the analysis method. Because of the difference in traffic flow as demonstrated in actual geometric design (e.g. gradient, slope length and curvature radius, etc.), it cannot be reflected in the same terrestrial landscape.
• The analysis method is lacking of characteristics for localized traffic flow. Further, appropriate method is also unavailable for analyzing the impact to the overtaking section, slope section and horizontal curve section.

　　In the updated “Suburban Dual-Lane Highway”, the Analytical Mode (Formula and chart) is based for simple road section and the Simulation Mode is applied for complicated section (Comprising the slope or a series of horizontal curves or overtaking section, etc.).

Promotion of Result：

　　Using the Highway Capacity Manual as the traffic guidance in order to assess the planning design and the performance improvement. However, the manual contains a variety of highway facilities and all sorts of calculation formula and chart. Furthermore, it even uses the simulation mode for carrying out the analysis. To improve the efficiency of the capacity analysis, this Institute launched the development of “Taiwan Area Highway Capacity Analysis Software (THCS)” starting from 2005. In the meantime, we also developed the subsystem to support the chapter updating in recent years and provided the education and training in order to promote the capacity analysis method.

　　In 2016, we developed the new version of “Suburban Dual-Lane Highway” subsystem. In October 2016, we invited Directorate General of Highways, competent county/city government, consultant and schools for conducting the education and training. Through lecturing courses, physical model and hand-on operation, it is hoped that the users would understand the new version of analysis and software operation method.