A comparison of trip production rates developed from two types of travel survey diaries

Abstract

In recent years, two types of travel survey diaries have been used to collect travel behavior data for transportation planning: travel diaries and activity diaries. In the travel diary, respondents are prompted to respond for each trip. Further questions are used to collect other information about each trip. In the activity diary, the respondent is prompted to respond by each activity. If travel is required for that activity, the respondent is then asked about that trip. Both collect the same I . nformation, but the recall frameworks are different. The primary objective of this research is to provide a statistically valid comparison of the trip rates reported by the activity diary to those reported by the travel diary. Additional purposes are to understand the nature of any differences and to understand why these differences exist. For this study, data from two Los Angeles area surveys are compared. The first is the 1991 Southern California Origin/Destination Survey, which was conducted using an activity diary. The second is the California Statewide Travel Survey, which was conducted using a travel diary. The travel diary reported higher trip rates than the activity diary, especially for driver trips. This difference is explained by differences in the reported rates for the shopping and "other" activities. Evidence suggests that the difference is due to the way in which people perceive "activities" and "trips. " Some "activities, " may be seen as taking place at multiple locations. As a result, the activity diary may not record the trips internal to this activity. Likewise, some "trips" may be seen as including minor activities along the way. As a result, the travel diary may record a single "trip" where two or more smaller trips had actually taken place. The findings of this research suggest that, in the short term, the travel diary should be used for collecting travel behavior data. The activity diary, however, may be preferred where the application of an activity-based model is likely. For the longer term, the development of a new instrument combining the best characteristics of the travel diary and the activity diary is recommended.