U-SARAH-LogoInstitut für Verkehrswesen

U-SARAH live - Simulative Optimization and Field Test of an Emission Based Dynamic Freeway Control System

Die Autobahn GmbH des Bundes
Dynamic Freeway Control System at Nordwestkreuz Frankfurt
Problem Statement

In Germany, dynamic freeway control systems are an important part of the traffic infrastructure on freeways. Variable speed limits, congestion warnings or overtaking prohibitions are automatically displayed via variable message signs depending on the traffic situation. The drivers are influenced by these traffic signs and traffic flow is thereby harmonized. In addition to increased traffic safety and optimized traffic flow, dynamic freeway control systems reduce air and noise emissions. The question arises whether a further reduction of emissions is possible.


The objective of U-SARAH live is the development, implementation and evaluation of an environmental control logic in existing dynamic freeway control systems. For this purpose, the approach of the feasibility study U-SARAH will be further developed. The environmental impacts are to be reduced without unnecessarily slowing down traffic. The aim of the research project is to gain findings on the runnability, the acceptance of road users and the effects of environmental control in test operation.


With AI-based methods existing data sets of freeways are analyzed. This results in an acceptance model (How are dynamic speed limits and warnings perceived?) and a forecast model (How will traffic develop in the next few minutes?). With a microscopic traffic flow simulation of a freeway, the conventional control logic (named SARAH) is extended by the acceptance model, the forecast model and environmental control criteria. The new control logic will be evaluated in a test run on a real freeway equipped with a dynamic freeway control system using real emission measurements.