The ninth part deals with measuring methods suitable for collecting traffic flow data. They are subdivided primarily according to the subject of measurement. The starting point is the collection of all vehicle trajectories over a given road section and within a given period. Firstly, measuring methods are dealt with which are suitable for collecting all these trajectories. These are aerial photography methods and measuring systems in which a system of detectors is applied to the road at comparatively short distances. Secondly, measuring methods are discussed which take a sample in the vehicle trajectories, i.e. several isolated or a limited number of adjacent trajectories are observed. Instrumented vehicles are mainly used for this. Thirdly, the sample in space is discussed, with which the traffic flow is observed on one or more road cross-sections. This is the most widely used measuring method but will be dealt with only briefly. Fourthly, the sample in time is discussed, the traffic flow being observed at a number of moments. This can almost only be done with an aerial photography method. Lastly, a number of methods that do not fit in with the classification are discussed. A number of aspects are mentioned which are important in evaluating a measuring method. In discussing the various methods, evaluation is made by reference to this list. Details of equipment are not gone into. For part I-VIII see IRRD abstracts nos 240606-240609 and 261941-4.
Samenvatting