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Industrial Ethernet Book Issue 112 / 19
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A brief history of the evolution of street lights, from gas lamps to smart lighting

Street lights have been around since the days of the ancient Roman civilization. For the 1,700 years since their use was first recorded in the city of Antioch, they served one single purpose: to provide light during the night. But today this is changing.

THE FIRST USE OF STREET LIGHTS was recorded in the 4th century in the city of Antioch in Turkey, which was part of the Roman empire back then.

The only light sources available at that time were candles, which provided only sparse illumination. Until the 17th century it was common practice that people would hire a lantern-bearer to get home safely at night.

Gas lights

The situation improved dramatically when in 1726 Stephen Hales invented the process to produce flammable gas from the distillation of coal. It was probably the Scottish engineer William Murdoch who first installed a coal gas light outside his house in Redruth, Cornwall.

Use of the practical and efficient gas lights quickly became popular. By the middle of the 19th century, all of the Grands Boulevards in Paris were lit with gas, earning the city the nickname "The City of Light". Following this success, gas lighting spread to other countries. In the U.S., Baltimore was the first city to use gas street lights.

If you are interested in the historical development of gas lights, there is a gas light open air museum in Berlin. Located near the Tiergarten S-Bahn station, it offers a collection of nearly 100 gas lamps, both originals and replicas, from 36 cities. The oldest dates back to 1826. Some of them have very peculiar names like "Wilmersdorf Widow" and "Copper′s Leg". The diversity of lantern designs covers everything from an ornate candelabra to simple, modern day concrete mast.

Yablochkov candle

The next major innovation was electric street lighting. In 1875, Russian engineer and businessman Pavel Yablochkov developed an "electric candle", which was named after him. It was a carbon arc lamp, which ran on alternating current.

Yablochkov candles lighting the Avenue de l′Opéra in Paris

The United States was especially quick in adopting this new technology. Already by 1890, more than 130,000 Yablochkov candles were in operation all across the country. The arc lights emitted a much brighter light than the old gas lights, but had the disadvantage that the electrodes burnt away quickly, requiring regular maintenance.

For that reason they were later replaced by first incandescent lightbulbs, and then by high-intensity gas-discharge lamps. These are still used most commonly for street lighting today, mostly in the form of high pressure sodium lamps, which provide good energy efficiency and long life.

Lights become smart

Today, new technologies such as LED are introduced, and street lights start to become more than simple light sources, they become smart. City lighting has always been a major concern, as it represents 10% to 20% of the electricity use in most countries. A Juniper Research report predicts, that cities could benefit from $15bn in cumulative energy savings through to 2023.

This is partially due to the better energy efficiency of LED technology. A significant amount of energy can also be saved by a more intelligent control of the lighting system. Using Internet of Things connectivity, lamp posts sense the environment and share their views with each other. This enables them to make informed decisions about lighting depending on the real-time necessities at their location.

Based on sensor information about weather conditions and detection of pedestrians, the system adapts the level of lighting.

Predictive maintenance

Another aspect is maintenance. Today it is difficult for a lighting network operator to find out if a certain lamp came out of action and needs to be repaired or replaced.

Typically, this is only discovered when people are reporting idle lights, and it is unlikely that the information will reach the operator immediately. Therefore, the delay between the time the lamp is broken and it is repaired can be quite long.

In a networked system, every street light becomes part of an accurate inventory. Operators get a complete view, enabling them to manage workflows and deploy maintenance crews only when and where needed. Real-time system data provides insights into energy use and cost. It also allows users to plan and schedule predictive maintenance, rather than waiting for a lamp to fail.

Beyond illumination

Beyond providing illumination, a smart street lighting system can be used to help emergency personnel. For example, if a car accident occurs, the nearby lamps can be programmed to flicker off and on, or to change their color. This alerts emergency vehicles to the exact location and signals other drivers to slow down.

Smart city platform

Street lights possess several characteristics that can make them the backbone of a smart city infrastructure. They are already everywhere in a city, and they are connected to the power grid. This makes it easy to add additional sensors and modules. They can be equipped with access points to provide city-wide WiFi coverage, and they can serve as charging stations for electric cars.

Sensors or IP cameras on the light poles can monitor parking spaces, helping local authorities to manage their parking areas more efficiently. The same technology can also be used to capture the flow of movement on streets. Feeding this information into intelligent traffic signs can help to avoid traffic congestions. The street lights can also be fitted with weather monitoring and air quality sensors. Having access to sensor data from hundreds of locations around the city is valuable for the authorities. It can help with the planning of snow removal and road salting, or to prepare for extreme weather and natural disasters.

For the street light of the future, illuminating the road will be just one of the many functions that it performs.

Leopold Ploner

Source: Industrial Ethernet Book Issue 112 / 19
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