Overview
The purpose of the weather TAT module is to provide Traffic Management Center (TMC) operators and traffic engineers with practical guidance for implementing proper traffic operational strategies specific to inclement weather conditions.
Traffic Analysis Toolbox Volume XI includes six chapters. The following provides a brief description of each chapter:
Chapter 1, entitled "Why Weather?", presents a brief overview of the topics covered in this TAT weather module. Topics included in Chapter 1 include: weather impacts on the transportation system, the available traffic analysis and modeling tools that incorporate those impacts, and the benefits of incorporating weather analysis into traffic operations and management strategies.
Chapter 2 elaborates on the discussion of weather impacts on the transportation system. Examples of these weather impacts are given on two traffic analysis levels: the macroscopic level and the microscopic level. The macroscopic level impacts discussed in this chapter include the weather impacts on traffic stream parameters, such as capacity, volume and speed at capacity, for an aggregated group of vehicles. The section on microscopic-level impacts addresses weather impacts on traffic parameters that correlate with the individual vehicular movements (e.g., lost startup time and saturation headway).
Chapter 3 starts with a brief overview of the three main types of traffic analysis tools (i.e., macroscopic, mesoscopic, and microscopic) that describes the capabilities and limitations for each type of tool. It then provides procedures for conducting weather-related traffic analyses using mesoscopic and microscopic traffic simulation tools (note that macroscopic tools are not considered as they have not been employed in weather impact analysis).
Chapter 4 presents examples of available weather, traffic, and Intelligent Transportation Systems (ITS) data sources that can be used to conduct a weather-related traffic analysis. Discussions of Clarus, the Highway Performance Monitoring System, and the connected vehicles initiative are included in this chapter.
Chapter 5 discusses on Weather Responsive Traffic Management (WRTM) Concept of Operations and existing traffic management strategies that would benefit from weather impact analysis.
Finally, Chapter 6 provides two case studies that were conducted to analyze weather impacts on traffic operations using mesoscopic and microscopic traffic modeling tools. In the first case study, DYNASMART-P, a mesoscopic traffic modeling tool, was used to develop models that estimated and predicted inclement weather impacts on freeway segments in the Hampton Roads region of Virginia. The second case study used two microscopic traffic modeling tools, CORSIM and SimTraffic, to evaluate weather-specific signal timing plans for four New England corridors.