In an emergency every minute counts. But in urban areas, ambulances, and other rescue vehicles, often have difficulty making headway due to dense traffic or construction sites. When using sirens and flashing lights, the rescue teams do not have to stop at red lights; however, this can be dangerous for other road users at the intersection. So, what measures can be taken to help fire trucks and ambulances reach their destination more quickly and safely? A German research project “SIRENE” focuses on solutions that enable emergency vehicle priority.

In this project, commissioned by the Federal Ministry of Transport and Digital Infrastructure,  researchers worked on a smart navigation system that includes short-term changes in traffic into route planning solutions.

In addition, modern communications technology was tested: In the pilot city of Braunschweig, in North Germany, ambulances and fire trucks were equipped with LTE mobile communication and so-called Car2X communication. The latter allows the vehicles to exchange information with other vehicles or the traffic infrastructure, for example with traffic lights.

The experts also tested different approaches to manage traffic lights smartly and thus enable emergency vehicle priority.  PTV expertise was used in the process.

“In public transport, it’s already common practice to give buses and trains priority at signalized intersections. PTV Epics is a software for traffic-adaptive signal control.  The solution continually optimizes the switching of traffic lights and thus reduces waiting times for public transport and cars, but also for pedestrians and cyclists. Smart traffic lights also help to reduce emissions. They reduce stop-and-go and thus improve traffic flow,” says Silke Forkert from the PTV Research team that supported the project. “For SIRENE, we adapted our software concerning Car2X communication and emergency vehicle priority.”

Every second, the software forecasts the traffic situation for the next 100 seconds, uses an internal model to evaluate the various control options, and applies the best option.

“Traditionally traffic lights are controlled by so-called flowcharts – special logics, that must be planned and programmed separately for each route to determine how the signal system should react in defined situations. If a bus is triggering a road detector a specific sequence is defined. The traffic lights clear the way for the bus,” explains Florian Weichenmeier of PTV, who was responsible for the technical implementation. “Our software, on the other hand, is an adaptive signal control system. It optimizes the switching of traffic lights adapted to the current traffic situation.”

The software prioritizes traffic modes according to different degrees. If a top-priority security or emergency vehicle reports via Car2X communication that it needs free passage, the software manages the traffic lights accordingly, allowing the vehicle to pass the intersection without slowing down – while affecting other road users as little as possible.

“Unsing PTV Epics is easier and more flexible than conventional control methods, as it is not necessary to elaborately re-plan every single traffic signal,” says Florian Weichenmeier.

How smoothly a emergency vehicles priority system can work, was demonstrated by the PTV experts in a simulation created as part of the research project.

Silke Forkert sums up: “With SIRENE we built the foundation to easily equip traffic lights with controllers that integrate modern Car2x technology, enabling emergency vehicles to pass more safely and quickly. This can help to save lives.”


The research project ‘Acceleration of Safety and Rescue Operations through Green Waves and Optimised Routing – SIRENE’, commissioned and funded by the Federal Ministry of Transport and Digital Infrastructure (BMVI), run from 2017 until 2021.

The network coordinator is the Institute for Automation and Communication e.V. in Magdeburg., Germany.

In addition to PTV Group, other partners were involved: AFUSOFT Kommunikationstechnik GmbH, Königsbach-Stein, the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt e.V. – Institut für Verkehrssystemtechnik, Braunschweig), GEVAS software Systementwicklung und Verkehrsinformatik GmbH, Munich, and the City of Braunschweig – Fire Department.

The project volume amounted to 2.57 million euros, the BMVI’s funding share accounted for 78%.


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About the Author

Sustainable forms of mobility like cycling, autonomous driving, road safety and strategies for the last mile: Steffi is fascinated by the variety of different topics mobility has to offer. She is always looking for new and exciting stories to write about.

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