Recent Practices in Regional Modeling of Nonmotorized Travel

TRB Special Report 288: Metropolitan Travel Forecasting: Current Practice and Future Direction identified treatment of nonmotorized travel in regional models as one of eight modeling deficiencies and also as an advanced modeling practice. However, that report and other existing literature provided little information about recent practices. This paper reviews the current practice of incorporation of nonmotorized travel in regional travel demand models in the United States, especially the models of large metropolitan planning organizations developed over the past decade. Overall, some progress with the representation of nonmotorized travel in regional models has been made. This paper discusses and summarizes modeling approaches, including the variables and data used, data issues, and lessons learned; summarizes the major issues and challenges that modelers face when they incorporate nonmotorized travel into regional travel demand models; and makes recommendations for future improvements to models. Recent examples of different approaches to modeling of nonmotorized travel in regional models are also presented. The pros and cons of each approach, including their different data needs and different abilities to evaluate policies and planning scenarios, are discussed. When deciding on the approach that they will take to modeling of nonmotorized travel, agencies need to know the data requirements, model development efforts, and policy sensitivities desired. In the trip-based modeling framework, further enhancements can be made through the use of more refined zone systems and more accurate measurement of variables, although the activity-based modeling approach is more promising. Regardless of the approach taken, targeted and enhanced data on nonmotorized travel and nonmotorized travel infrastructure are greatly needed.