The pace of behaviour change and implications for TDM response lags and monitoring : findings of a retrospective commuter travel survey in Cape Town

Abstract

This paper discusses the findings of a retrospective travel survey conducted in Cape Town during 2006 with respect to the pace at which change in commuter travel behaviour occurs. Data were collected in four residential areas in which a large portion of households fall within the R3,000-R6,000 income band, observed in other data sources as strategic from a car ownership and mode switching perspective. The paper identifies the different elements of a commuting trip decision as origin, departure time, mode, route (if private transport), vehicle occupancy (if private transport), and destination. It discusses the findings of the survey with respect to the distribution of time elapsed since change in usual behaviour for each of these trip decision elements, as well as with respect to the distribution of time elapsed since change in usual behaviour has been considered but not acted upon. The paper concludes with a discussion on the implications of these findings for understanding possible behavioural response lags following TDM intervention, and for appropriate timeframes for TDM strategy monitoring and revision.