Resumen
This article is a generalization of the author?s experience gathered when preparing transport development forecasts in Poland over the past quarter of a century. These forecasts have proved to be less accurate when prepared using only quantitative and strictly mathematical methods, and more accurate when the change indicators have been estimated using the expert (intuitive) method. The problem of inaccuracy of economic and transport forecasts can be explained by the notion of predictability, which makes it possible to divide phenomena into those that are more difficult or easier to predict and to identify phenomena that are not predictable at all. The existence of unpredictable phenomena has its source in influencing the reality of systemic determinants and random factors that have no bearing on the timeline. Predicting the need for transport requires the use of different methods for freight transport and different methods for the transport and mobility of people. The source of changes in the volume of the transport demand are predominantly fluctuations in the intensity of production and consumption, and changes in the need to cover space and, to a lesser extent, this source is the generation of new demand through the additional supply of services and transport capacity. Owing to the increasingly comprehensive statistics from past periods it is possible to establish that the correlation between the GDP and freight traffic is much weaker than previously thought. The demand for transport and mobility of people is less dependent on economic activity, and more dependent on demographic changes, the lifestyle of the population and the preferences in choosing the means of transport.