Variations in the rational use of time – The travel pulse of commutes between home and job

William Michelson

Rationality, suboptimization, commuting, time of day, travel mode, gender

Ian Cullen and his research colleagues long ago suggested that people form habits in daily life that suboptimize behavior in view of constraints. Such rational suboptimization is posited here to apply to trips between home and work and to vary by time of the day. Previous research suggests that afternoons prove more difficult for people than mornings, with rush hour traffic patterns shown as one aspect. This paper contrasts with episode level data from Statistics Canada’s 2005 time-use survey the temporal pattern (shown as a “travel pulse”) of weekday commutes between home and job by full-time workers with external workplaces. The mean trip duration in the morning is less than in the afternoon, as is its standard deviation. This is rooted in a visibly greater dispersion of rational starting times from home in the morning with arrival at work at various times in advance of the start to the formal work day, while, in the afternoon, people typically depart from work directly at externally-determined closing times and in concentrated peaks. The result is that nearly twice the number of commuters set out at the same time during the afternoons than in the mornings. The less than individually-rational intensity of the afternoon commuting context is compounded by the concentration of everyday shopping stops during the afternoon commute. Mode of travel accounts for significantly different mean trip times, but differences in trip duration by time of day transcend travel mode. Differences by gender interact with mode of travel but are not generally significant. The rich legacy established by Andrew Harvey is apparent, as he has been an influential shaper and advocate of the Statistics Canada’s time-use surveys, the use of such data for transportation analyses, and a focus on episode-level analysis.