Forecasting External Trips in Small and Medium Cities Based on Local Economic Context

The external trip estimation is important but usually neglected in travel demand modeling process for small and medium urban areas. This research develops a cost-effective method to forecast external trips from an economic point of view. A concept of Employment Index (EI) by NAICS sectors was initiated to represent local economic characteristics in statewide context and approved to be significant in predicting external trips. Based on recent survey data, separate external trip models were developed by urban categories. The new models minimize data requirements and are easy to use. They appear transferable to other small and medium urban areas.