November 2023
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27 Reads
Network management systems (German: Netzbeeinflussungsanlagen - NBA) are one possibility to manage traffic in the road network optimally in accordance with the existing traffic loads and travel times, especially in the event of disturbances in the traffic flow. The methods currently used for impact assessment of NBA based on the guideline “Hinweise zur Wirksamkeitsschätzung und Wirksamkeitsberechnung von Verkehrsbeeinflussungsanlagen” (FGSV Issue 311) calculate the effects on traffic flow using time costs. However, the parameters included in the procedures are empirically difficult to determine and are based on assumptions, especially for the compliance rate and for the travel times on normal and alternative routes. The aim of the research project was to develop an assessment analysis method that supports proof of the traffic effect of NBA in a more transparent and practical way. Based on a literature review of procedures for assessment analysis and control strategies of NBA as well as expert interviews with representatives of the road administration, relevant impact components were identified and their actual options for calculation evaluated. The use cases “traffic disturbance information” (use case S) and “alternative route recommendation” (use case A) for NBA were established in a new analysis method for ex-ante and ex-post investigations because of these findings. Information from Floating Car Data (FCD) is used to assess the relevance of disturbances and the estimation of travel times in undisturbed and disturbed situations, time losses due to the disturbances and resulting time advantages. The transmission of the traffic disturbance information at the decision point (use case S), whether with or without additional recommendation of an alternative route, also has an influence on the behavior of road users. For use case S the number of road users informed about the disturbance is used to assess the effectiveness of an NBA. If, in addition to the traffic disturbance information, an alternative route recommendation is shown, the use case A for the relevant time range is also considered. The procedure in use case A assumes that a recommendation of an alternative route results in time advantages for the road users following the recommendation compared to continuing the drive on the normal route with the disturbance. To assess the traffic impact of NBA for use case A, the sum of these time advantages for all relevant road users in passenger car and truck traffic is used. For this purpose, the characteristics of the network of normal route and alternative route are analysed. From this analysis, indications of the relevance of disturbances on the normal route for use cases S and A can be derived. A further distinction is made between the traffic volume of road users entering the normal route and the traffic volume of those passing through the entire normal route to the end point (usually in an undisturbed situation). Furthermore, information about the number of road users who are switching to the alternative route is required. Additionally, data on disturbances and in the case of ex-post investigations also data on display contents of the NBA are needed as input data. On the alternative route, the network element that has the lowest capacity must be located. With the analysis method, the traffic effects of an NBA can be calculated. In use case A, the time advantages for the influenced road users (passenger cars and trucks) are shown. The benefits of the NBA can be determined based on time advantages using time cost rates. In addition to the procedures for effectiveness analysis, a methodological approach to the strategy definition for NBA is developed, which is based on the same principles as the assessment of traffic disturbances. In the context of an exemplary practical application, it was shown that the processing steps described in the procedure and the necessary data are suitable and the method is usable for an impact assessment of NBA. Finally, recommendations are formulated for the integration of the project results into the FGSV guidelines. In addition, information is given on how to improve the application of the method. Necessary data should be available in standardized data formats and in a continuous data storage. To simplify the application, a software tool should be implemented and the knowledge gained from process applications should be collected in a knowledge repository.
