Regulating traffic by controlling land use The Southern California experience

In Los Angeles emphasis in transportation planning has recently shifted from facility construction to transportation system management and the control of land use with the goal of slowing the growth in traffic congestion. This paper critically examines several recent transportation growth management strategies in Los Angeles, and concludes that though they were well intentioned, they might not lead to the intended consequences.     

A GA-based household scheduler

One way of making activity-based travel analysis operational for transport planning is multi-agent micro-simulation. Modelling activity and trip generation based on individual and social characteristics are central steps in this method. The model presented here generates complete daily activity schedules based on the structure of a household and its members’ activity calendars. The model assumes that the household is another basic decision-making unit for travel demand aside from individual mobility needs. Results of the model are schedules containing complete information about activity type and sequence, locations, and means of transportation, as well as activity start times and durations. The generated schedules are the outcome of a probabilistic optimisation using genetic algorithms. This iterative method improves solutions found in a random search according to the specification of a fitness criterion, which equals utility here. It contains behavioural assumptions about individuals as well as the household level. Individual utility is derived from the number of activities and their respective durations. It is reduced by costs of travelling and penalties for late, respectively early arrival. The household level is represented directly by the utility of joint activities, and indirectly by allocation of activities and means of transportation to household members. The paper presents initial tests with a three-person household, detailing resulting schedules, and discussing run-time experiences. A sensitivity analysis of the joint utility parameter impact is also included.     

Some issues of dynamics in forecasting travel behaviour — A discussion paper

In the next few years there is likely to be a large growth of interest in the dynamic modelling of travel behaviour. In order to try to avoid the eventual collapse of enthusiasm which has sometimes occurred with other new developments when they turn out not to provide transport planning with the hoped-for panacea, this paper aims to demonstrate the diversity of approaches which will be required to tackle the subject of dynamics. In particular, it identifies three overlapping but distinct levels at which dynamics interact with travel behaviour — microdynamics, which is concerned with the detailed scheduling of activities and travel within a day — macrodynamic modifiers, whereby changes in medium- and long-term behaviour which are often considered to be instantaneous are in fact subject to important phasing considerations — and macrodynamic processes, which deal with the overriding demographic processes of birth, ageing and death. The paper suggests approaches to the incorporation of these three topics into the forecasting of travel behaviour.