This paper describes research that is part of the European Communities' DRIVE II DYNA project. The paper presents a practical approach to on-line link-performance modelling. The on-line procedure comprises the computation of a scaling factor for each individual link in a pilot area in the Netherlands. The scaling factor is used to scale both the speed-density function and the capacity for each individual link. Results from a few monitoring stations show that the on-line link-performance module works properly. The results are somewhat better during the non-congested state than during the congested state. However, under these circumstances the general pattern is also reproduced. During congested periods During congested periods the DYNA system uses an explicit queuing model. The evaluation shows that the speed-density curve applied in congested situations gives acceptable results, even though no calibration has been undertaken for this part of the curve. Additionally, a method is shown to predict congestion. The results show that on-line estimation of link characteristics of medium-sized networks with a diversity of link types is manageable. The on-line estimated link characteristics have been implemented in DYNA and form essential information to the DYNA forecasting models.
Abstract