Smart City becomes tangible - street lighting as the key to digital networking

 

The latest generation of LED luminaires is based on the so-called System Ready architecture. The luminaires feature a standardized Zhaga Book 18 connector at the top and bottom, combined with the latest LED drivers. This manufacturer-independent luminaire concept allows a light controller to be connected at the top and an additional sensor module at the bottom. Mounting is done without opening the luminaire - simple plug-and-play. The System Ready concept thus allows the life cycles of the luminaire and external components to be decoupled.

DigiStreet luminaire with System Ready architecture

The communication protocol based on DALI ensures here that System Ready modules from different manufacturers are compatible with the luminaires. In September 2018, the existing DALI standard was supplemented by DiiA (Digital Illumination Interface Alliance) with new specifications that define a standardized data exchange between LED drivers and lighting controllers. Thanks to this extension, luminaire information, energy data and status information of the luminaire can now be read out via the DALI interface.

System Ready luminaires thus form the basis for future smart city applications. Parking space monitoring, measurement of environmental data such as noise immissions, fine dust or nitrogen oxide pollution are possible tasks that can be taken over by street luminaires in the future.

Each city or municipality has individual needs and places different requirements on its infrastructure. Therefore, the solutions used must be scalable and expandable. System Ready luminaires offer this flexibility and can already be used across the board when refurbishing to LED, to be equipped with the appropriate lighting management controller and sensor technology at the appropriate time. Compatibility with products from different manufacturers increases flexibility in the selection of suitable components. Complementing this, especially in central locations of a city, multifunctional light poles can add value.

From the luminaire to the multifunctional light pole

Even for components with higher technical requirements (such as IP cameras, Wifi access points or e-charging stations), mounting on the luminaire is not practical. Here, a multifunctional light pole, as already in use today in the city of Wädenswil, offers the possibility to combine several applications in one light point. A light point that provides light, serves as an e-charging station, supplies the population with WLAN and is used to collect environmental data and measure traffic.

The traffic sensor enables the classification of vehicles, identification of the direction of travel as well as measurement of speed. Thanks to thermal imaging technology, the sensor reliably distinguishes between motorized traffic and bicycles even at night and under the most adverse weather conditions. Measurement values for particulate matter, Co2 and ozone are recorded via integrated environmental sensors.

A major advantage of the multifunctional light pole is that it is tangible for the population - and thus raises awareness of the smart city issue. As a prominent anchor point at a central location of a city or a municipality, such a light pole has lighthouse character and can be experienced by the residents. As has been shown in Wädenswil, a light pole can become the initiator for further smart projects.

The use of sensors alone does not make a city a "smart city. Rather, the measured values serve as a basis and only develop their potential through consolidation and evaluation on a central platform. Existing data from third-party systems also flows into this new, interdisciplinary approach. This can come from existing sensors in the areas of traffic measurement, traffic light control, or the collection of environmental data. New insights can be gained and synergies exploited from the joint analysis.

Smart City Cockpit

The visualization of the evaluated data can happen, for example, in a Smart City Cockpit. This platform shows the most important information about the state of a city at a glance. The example of Wädenswil (Fig. 4) shows how data from different infrastructure elements flow together. In addition to the data from the multifunctional light pole, information from other systems in the area of light management as well as waste management is also displayed.

The consolidated information can be used not only by the city or municipal administration and the infrastructure operator, but can also be made available to the population. Different user roles can be used to manage the level of detail of the visualized information. In this way, each user has access to the information that is of interest to them.

The data processing and consolidation on a central platform enables the use of synergies. As part of these new possibilities, for example, a multifunctional light pole could be installed at a traffic signal intersection to record traffic flow as well as various environmental values. The visualization of the measured values in the Smart City Cockpit shows operators that an above-average level of particulate matter is forming at this intersection. In the analysis of the traffic data, it becomes clear that this problem is caused by long-standing trucks.

In such a case, it would be possible to use a central platform to control the traffic signal according to the traffic volume. As soon as more than three trucks are at the traffic light, it switches to green. With this combination of environmental sensors, traffic measurement and traffic light control, the city could efficiently detect and immediately reduce environmental pollution.

There is also great potential in the demand-based and efficient control of street lighting through the use of sensor technology. Here, too, the traffic volume is measured via a sensor and the data is mapped on a central platform. There, the traffic volume is evaluated according to the SNR 13201-12 standard and the light level is adjusted according to the calculated lighting class. A control command is now transmitted via the software interface between the Smart City platform and the light management system, and the street lights are thus dimmed according to the standard-compliant light level. Thus, the sensor for traffic measurement forms the data basis for different areas of application.

This form of traffic-dependent lighting control has been implemented in various pilot projects and is particularly suitable for heavily trafficked roads. However, there are also alternative lighting control concepts that are equally justified depending on the needs and requirements of the community. The use of different concepts is expedient in order to comply with the requirement of "demand-responsive lighting".

Today, there are already concrete approaches to networking infrastructures. The latest technologies offer the necessary flexibility and scalability to take the first step toward a smart city. In this context, the existing network of public street lighting forms the ideal carrier infrastructure for sensors and actuators. By using a central smart city platform, the data can be viewed in a consolidated manner and used for cross-system applications. On this basis, public lighting can be successively expanded into Smart City infrastructure.