This paper presents a methodology for increasing the reliability of route suggestions in route guidance systems. The procedure, based on the A* path-finding algorithm and Chen's link penalty method, involves penalizing links with a high risk of being congested and obtaining a set of reliable route suggestions. Time dependence of travel times is considered by adapting the flow-speed model technique accordingly. The structure of the path-finding algorithms is also modified to account for real road network features. Finally, experiments using simulated travel time and reliability data are carried out on a road network, and the results are discussed.