With Siemens traffic control systems, all types of traffic control systems can be implemented on highways – either individually or in combination.


All Siemens traffic control systems consist of sensor systems for the capture of traffic and ambient condition data, along with components for communication between field devices and central control. The product spectrum includes:

  • Route Control Systems Route control systems stabilize traffic flow; they also include systems for speed homogenization and lane signaling.

  • Hot Spot Control Systems - Hot spot control systems separate competing traffic streams at conflict points. One example is highway entry control.  

  • Network Control Systems Network control systems use variable message signs to guide traffic from overloaded routes to network sections with available capacity.


Sensors measure factors that provide information about current conditions – including brightness, traffic volume, and weather conditions. This data is vital for automatic traffic management.

Siemens sensors provide current, precise data on the following factors:



  • Visibility
    The visibility sensor identifies low visibility conditions caused by fog or snow, and transmits the visibility data to the higher control center.

  • Environment Sensors
    Data such as air temperature, wind direction, and wind speed – as well as type and intensity of precipitation, road surface temperature, residual salt content, etc. – are documented by a weather and environmental-data station.

  • Brightness Sensors
    Brightness sensors are used to adjust the lighting level of the variable message signs. The very high light intensity of the VMS ensures good daytime visibility even when the sun is low. At night, the VWS are dimmed so that motorists are not impeded by glare and the symbols are not too bright.

  • Loop Detectors
    Loop detectors provide all necessary statistical data. The loop detectors classify the vehicles into classes (up to 8+1). All loops are doubled so that they can determine not only the number and type of vehicles, but also their speed and direction.

  • Above Ground Detectors (AGD)
    AGDs can be installed instead of loop detectors to provide the same types of data. Due to recent developments, AGDs are almost as accurate as loop detectors, but are considerably faster to install.


Actuators react to changes in conditions and adapt to new situations by informing motorists of the current conditions – either automatically or manually. This, in turn, facilitates safe and smooth traffic flows.

The comprehensive Siemens portfolio includes the following actuators:



  • Variable Message Signs, Speed Limit Signs
    Variable message and speed limit signs (VMS and SLS) use LEDs to display text information or traffic symbols. The LED elements are monitored by their control unit to prevent disrupted, illegible, or contradictory displays. An optional hardware lockout can also be installed.

  • Lane Control Signs (LCS)
    Lane Control Signs use LEDs to display lane signals with arrows. The display elements are monitored to prevent unsafe signaling states. An optional hardware lockout can also be installed.

  • Lane Lights
    LED lane lights are set into the roadway surface, and can be used either for dynamic lane assignment or static shoulder marking.

SITRAFFIC CONDUCT+ Controlling and Management for Highways

SITRAFFIC CONDUCT+ is the further development of our proven control center on a new platform. It ensures safe, effective, and uninterrupted operation in both long-distance and urban highway networks.The CONDUCT+ control center receives all information on network utilization and the condition of all operating facilities. Sensors deliver data on traffic and ambient conditions – the control center applies defined strategies and rules to determine the appropriate measures to harmonize traffic.

The system is highly standardized and based on proven client/server technology. It uses Microsoft Windows or Linux operating systems, and is expandable at any time and in any direction. This means that it maintains its value over a long period of time – and that expensive overdimensioned systems are no longer necessary. The center grows with its functions, module by module, and is simply expanded when a new tech-nical system is added – such as access control or shoulder release for traffic. SITRAFFIC CONDUCT+ has a second server that keeps running in "hot standby" mode. If the active server is experiencing problems, operations are switched to the other server automatically, for maximum availability.

Variable Message Signs – Actuation

Modular variable message sign actuators can be used very flexibly and, at the same time, they ensure a high degree of availability of the triggered VMS. A patented system monitors the LEDs even when they are turned off, which means more safety for the motorist and improved economy in operation and maintenance. The VMS actuator can be used with both halogen fiber optics and LED VMS from different manufacturers. Due to the modular structure, with a controller module and up to 8 lamp / LED control boards, precise adaptation to the customer’s requirements is ensured.

Roadside Controllers

The SST4 roadside controller family is based on the existing TLS 2002, and comes pre-equipped to meet the requirements of the German Highway Research Institute (BASt). The future-proof PC104 standard, numerous communication interfaces, and the easy-to-maintain design are furnished as standard equipment. The SST4 offers plenty of room for expansion for elements such as GPRS, Ethernet, up to 20 loop detectors, FSK modem, and USV.

The SST4-XS is the "light" version – perfect for simpler applications such as a data collection tool, Inselbus communication computer, speed warning system, input/output concentrator, and more.

By using different installation frames with selected components, it is easy to create project-specific solutions tailored to the needs of the individual client – whether this involves the installation of the components into existing cabinets or into WMS (Variable Message Sign) housings, receded detector stations with solar power, or license-free radio connection.

ComBox – Communication Computer

With the ComBox from Siemens TS, the customer gets an "Inselbus Communication Computer" compliant with TLS specifications (German Highway Research Institute – BASt), offering a broad range of practical applications.

The ComBox has good computing performance and can manage up to 13 TLS inselbuses. It communicates with the subcenter by TLS or TLS over IP. It can be in contact with a large number of external systems in various ways (such as by radio or serially), and can provide compressed user data to various subcenters.

Thanks to many software tools used in conjunction with other Siemens checkpoint components, the ComBox is extremely service-friendly.