When considering methods of estimating the average speed of public transport vehicles the movement of these vehicles must
be analyzed, this includes travel time, loss of time due to various causes, and also allowing for the stop service times.
Identification and analysis of these factors should enable the formulation of a relationship between them and the average speed of
the vehicle. This paper presents the statistical summary of the results of travel time research conducted for Tri-City intelligent
traffic control system (TRISTAR) and show the complexity of the estimation problem for traffic modelling.