Today, the road side level of service (LOS) information is a commonly used measure for describing the current road network efficiency. It characterizes traffic flow or travel times by a small number of discrete traffic quality classes (e.g. free flow, dense traffic, traffic jam) and is one of the most popular kinds of traffic information in road transportation. In this context, LOS-based information is often obtained from single traffic data sources like floating car data or detector data without combining them systematically. In order to improve the quality of LOS-based traffic information a high level fusion approach is needed which integrates LOS data from various data sources. This contribution suggests a new methodology using a quality-weighted median approach to efficiently and generically fuse these LOS data. It principally handles the common discretization schemes and provides a stochastic algorithm for transforming LOS data of arbitrary scales. The new methodology is described together with a use case for a region in Germany and the technical description of the prototypical LOS data fusion software module as designed and implemented by the Institute of Transportation Systems of the German Aerospace Center (DLR)
