University of California Transportation Center

This dissertation examines the effect of work and non-work scheduling flexibility on the timing of work trips. It explores whether increasing activity scheduling flexibility, whether due to work or non-work factors, results in non-peak travel and hence shorter travel times. It examines in detail work scheduling flexibility, non-work scheduling flexibility, and travel time characteristics.

An examination of trip timing choices using data from the 1990 Bay Area Travel Survey showed that the likelihood of traveling during peak hours increases with work scheduling flexibility, and is only weakly related to non-work flexibility indicators. We conclude that activity flexibility indicators do not capture well workers' flexibility, and also that network travel time estimates do not represent accurately travel time differentials.

Data on work and non-work scheduling practices were gathered from a sample of full-time employees, using detailed personal interviews, self-administered questionnaires, and activity diaries. The survey collected factual information about work and non-work schedules, and attitudinal information about the discretion available to reschedule work and non-work activities. Data form an independent survey were used to estimate travel time as a function of time-of-day on each corridor used by the survey subjects.

It was found that work scheduling flexibility has three components: strategic or medium term flexibility, quotidian or short term flexibility, and the gradient or loss of schedule flexibility as the desired schedule diverts from the nominal work schedule. Only strategic flexibility plays a major role in work trip timing. It was found that many flexible workers travel during congested times of day because they must engage in mandatory, time-of-day dependent non-work activities. Flexible workers also choose to participate in discretionary activities which require them to travel in congestion. These flexible workers exhibit travel time penalties as large as the penalties of commuters who have rigid work schedules. The implication is that congestion pricing and other congestion alleviation policies will succeed in shifting trips from peak to non-peak hours only to the extent that workers are able and willing to reorganize their personal and family activities