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Trip Chaining A significant issue related to the importance of the land use adjacent to the work site is the matter of trip chaining. It has been argued that a major deterrent to shifting commuters away from driving alone and into transit, ridesharing, or other alternatives is the degree to which they are dependent upon their cars for needs and activities which occur at, or on the way to or from, the work site. Particularly in suburban areas, where work sites tend to be isolated from other land uses (especially services), commuters can feel justifiably nervous about abandoning their cars. In response to this isolation and dependency, commuters double-up on the purpose of their com- mute trip by incorporating additional stops on the way to or from work. These multi-stop trip tours, or "trip chains," introduce an additional challenge and complexity to planning for TDM programs. Multi-task commute trips are commonplace, and often hard to accomplish when not driving alone. When trying to entice the drive-alone commuter into a wholesale shift to an alter- native mode, much depends on how essential these intermediate stops are to the household, how frequently they are made, and whether or not there are options at the home or work end of the commute trip that can satisfy the same needs. A thorough study of this phenomenon was performed in the Brentwood area of Nashville, Tennessee, using survey data obtained from a sample of 1,845 employees representing 42 employers in this predominately suburban district. The survey probed in detail into the frequency with which the commuters made stops on the way to or from work, and also into their purpose. The survey found that only 9 percent of all workers surveyed traveled directly to and from work without stopping-- the vast majority made routine stops. It also found that stops on the return-home trip were twice as likely as stopping on the way to work. Table 19-29 gives an indication of how frequently trip chain- ing occurred (Davidson, 1991). Table 19-29 Frequency with which Non-Work Stops Are Not Added to the Commute Trip, Suburban Nashville, Tennessee Number of Days Respondents Go Directly To/From Work Without Chaining Trips Trip Direction 5 4 3 2 1 0 To Work 49% 18% 11% 5% 2% 15% From Work 19% 22% 26% 15% 5% 13% Source: Davidson (1991). The display shows the frequency with which employees traveled to or from work without making additional stops along the way. It reveals that almost one-half, 49 percent, of the commuters studied essentially never stopped on the way to work, although only 19 percent traveled from work to home without making a stop at least 1 day a week. So, viewed the opposite way, 51 percent of com- muters stopped at least once a week on the way to work, and 81 percent stopped at least once a week on the way home from work. The other interesting statistic in this display is the proportion of commuters who always stopped along the way: 15 percent of commuters stopped daily on the way to work and 13 percent stopped daily on the way from work. The average number of days a stop was made on the way to work is 1.38, while on the way home the average is 2.0 days per week. 19-102