AbstractsTransportation

This study is concerned with the manner in which motorists react when part of the road network is reduced in capacity. It is concerned with the habits associated with finding a route and choosing a mode. Knowledge of motorists’ responses is important in light of the increasing incidence of reductions in road capacity, due to road capacity being reallocated to other modes. Examples include pedestrianization, and the installation of bus lanes or street running light rail. Capacity is also reduced when infrastructure fails because of natural or man-made actions or lack of action. Authorities must ensure that traffic can cope with the disruption that reducing capacity brings, whether caused intentionally or unexpectedly. It has been noticed that traffic reduces after an incident of reduced road capacity, but only to the extent it needs to do so. The results of this study suggest a hypothesis to explain this observation. The field study described in this thesis consisted of a qualitative survey of motorists who drove along Epping Road in Lane Cove, Sydney, Australia, both before and after the reduction in capacity which occurred after the opening of the Lane Cove Tunnel in 2007. The motorists described their travel behaviour in relation to Epping Road. From their descriptions of their propensity to switch routes during the course of their trip, two hypotheses were developed, which offer a potential explanation for the disappearing traffic. The route switching hypothesis posits that a minority of motorists have a habit of changing routes to avoid the delays they encounter. They may change their route before the journey starts or while the journey is underway. The minimal chaos hypothesis states that: Route switching by a percentage of motorists, in combination with other motorists leaving the route or changing their time of travel, results in changes which tend towards the minimum necessary required to avoid on-going disruption. The variations in the motorists’ mode use habits can be explained by their level of travel competence, which is defined by this study as the ability to make informed choices between the available modes. This is achieved by acquiring both trip planning competencies and trip execution competencies. The thesis gives examples of the range of competencies required for the modes in widespread use in Sydney. It also gives an example of how enhanced travel competence affected travellers in a incident of reduced road capacity in Brisbane.