Abstract
An on- line prognosis system can be introduced not merely detect traffic overloads on road networks after they have appeared, but also to prevent their onset. The prognosis system must be highly reliable if the credibility and success of the information it provides is to be ensured. An example is given to show how prognosis accuracy of the road section under analysis can be significantly improved by the introduction of a control mechanism which calculates on- line prognosis error and makes use of it to improve the prognosis.