Hardbound. Societal trends have made the need for better travel demand forecasts more urgent, at the same time as making people's travel and activity patterns far more complex. Traditional traffic flow models are no longer sophisticated enough to cope.Activity analysis is seen by many as the solution. It has had a short but intense history in geography, urban planning, time use research and, more recently, transportation. Pioneering activity-based models have now been developed to the point where, some argue, it is time to abandon the traditional four-step model for transportation demand...