The decision support system RODOS (Ehrhardt and Weis, 2000) contains a large set ofsimulation models, data bases, user interfaces and system functionalities. However thesemany options resulted in heavy-weight and complex user interfaces difficult to handle bynon-experts. For this reason a user friendly and light-weight access to the RODOSfunctionalities was requested by the end users. This was fulfilled by the design andimplementation of a new user interface named RODOS-Lite. The main purpose of thisredesigned user interface is to gently lead operators through a sequential line of inputmasks, hiding rarely used parameters (defaults are set) from the operator but stillproviding the possibility to access them if necessary. Additionally, the interface isstrongly safeguarded to prevent operators from entering wrong input values. This isachieved by systematically checking input values and even suggesting occasionally bestestimate parameters. RODOS-Lite is complemented by various simple but neverthelessextremely useful features such as online access to Google maps or source termvisualisation.