Brilliant design: intelligent lighting and sensors in Smart Cities

The idea of ‘Smart Cities’ is one that’s becoming familiar to engineers. Partly an adaptation to more diverse sources of electricity, including small-scale renewables, partly a development of the so-called ‘Internet of Things’, allowing household appliances to adjust their electricity consumption to take account of fluctuations in prices, the concept is being trialled in many cities around the world and is of particular interest to countries building new cities, such as those in the Middle East and China.

But while a lot of attention has been paid to the components that make up the smartness of the cities — the electronic brains in appliances, electric vehicles, the electricity-distribution hubs, and the smart meters that are intended to allow domestic and business users to monitor their electricity consumption in detail — there has been less information around about the nervous system that connects all these processing centres. How will the smart components talk to each other? And what effects might that have on actually living in a smart city?

The answer, according to some of the largest electronic infrastructure providers, is likely to be in the air. A huge expansion of wireless broadband around the entire city, allowing devices to communicate via interlocking networks while at the same time enabling much wider-spread usage of devices such as smartphones, tablets and laptops.

The overall goal of smart-city infrastructure is to enable the city to use electricity (and other forms of energy) more efficiently.

But this network might have some unexpected effects. For example, Cisco Systems is proposing that it should be extended to the city’s lighting network.

James Crowther, Christopher Herzig and Gordon Feller of Cisco explain in a report, The time is right for connected public lighting in smart cities, that adding intelligence to LED street-lighting systems can not only reduce energy consumption, thereby saving money, but can also make cities safer and easier to navigate at night.

Lighting, the report says, accounts for 19 per cent of all the energy consumed worldwide, but street lighting — which accounts for a significant fraction of this — is often based on 1960s technology. Trials of LED lighting in 12 cities showed that they reduce energy usage by 50–70 per cent. Adding intelligence and connectivity to the system can reduce consumption by a further 10 per cent, they claim.

The report’s authors envisage several improvements that would be enabled by connected lighting. Centralised lighting control could be keyed to weather conditions, bringing lighting online early on cloudy, dull evenings or later when skies are clear. Light intensity could be keyed to local movement sensors, brightening when there are people and vehicles around and darkening when the streets are quiet. ‘This would make people aware of what is around them, allowing for better visibility and making them feel safer.’

Lighting could become part of a city’s emergency response, working dynamically to help emergency services

Businesses could also key into the lighting system, they suggest. Shops could use more motion sensors to detect the approach of pedestrians and brighten the lights, ‘creating an inviting atmosphere’, as they put it. More seriously, the lighting could become part of a city’s emergency response, increasing visibility of safe areas and even working dynamically to illuminate the best routes to an incident for emergency services — or the best escape routes.

The lighting poles themselves would play a part in this system, providing a high vantage point for data hubs and transmitters; other intelligent city-wide systems, such as traffic control, parking monitoring, waste management and even automated watering of plants in parks and along streets could piggy-back off the network.

Other systems that could be mounted on street furniture and connected into the network include atmospheric sensors, the report suggests. These could provide highly detailed and location-specific information on hazardous pollutants such as ozone, nitrogen oxides and carbon monoxide; levels of fine particulates that have been linked with respiratory disorders; and noise levels.

The advantages spread beyond the effects of the lights themselves into the areas of maintenance and finance. Currently, lighting outages are often detected by scouting teams, driving around the city at night; a network system would include self-monitoring to detect and report failures automatically; this also allows the system to plan the best routes for maintenance teams to minimise street closures and disruption to traffic and businesses. And, as with domestic smart metering, the system allows continuous monitoring of energy usage to provide the city authorities with accurate information on billing, however the lighting is used.

Systems such as these are starting to be installed around the world. In the UK, for example, Milton Keynes has installed a trial smart-lighting network for 400 LED lights linked to servers that track changes in sunlight levels and adjust the intensity of lights from midnight until dawn. This, claims system supplier Echelon, has ‘helped cut the city’s energy use by 40 per cent’, while also reducing maintenance costs and light pollution. The city is planning to replace ageing streetlights with more of the LED systems, leading to a total network of more than 100,000 lights.

Distributed wireless monitoring systems are also starting to appear. The central- Spanish city of Salamanca is anxious to protect the many historic buildings that made it a UNESCO World Heritage Site from the damage caused by atmospheric pollution, as well as protecting the health of its residents and visitors, and is taking part in an EU-funded programme called RESCATAME (a Spanish acronym for Pervasive Air-Quality Sensor Network for an Environmentally Friendly Urban Traffic Management). Using Waspmote sensors from Zaragoza-based specialist Libelium, the city is measuring temperature, relative humidity, noise and levels of particulates, CO, NO2 and O3 at 35 locations around the city, allowing it to monitor the air in real time and analyse the data. This will help the city build up a picture of how air quality varies across the city throughout the day and help planners design traffic-management systems to reduce pollution.

In Depth

The Spanish city that’s pioneering smart sensor technology

Best known for its beaches, or perhaps for the financial institution that was founded in the city and bears its name, Santander in Northern Spain is now carving out a niche as a test-bed for smart city technology. An area of 6km2 in the city centre holds 10,000 sensors on lamp posts, walls and beneath the roads, reporting in to a central IT system.

As Smart City Santander is a research project, mainly EU-funded, that IT system is at a university rather than at the city hall, as it might be in a fully functioning smart city. The system is operated by a research group led by Luis Muñoz of the University of Cantabria, the regional university based in the city. However, the local government has access to the information — as do the city’s 180,000 residents, via a smartphone app called Pulse of the City.

Among the parameters monitored by Muñoz’s sensors are air quality, air pressure, temperature and humidity, noise, and movement, both of traffic and people. As detailed above, monitoring of street lighting is built-in to the system, with outage reports and adjustment of lighting intensity. Loadcells monitor how much rubbish is in the city’s bins, so that the waste department knows when to empty them; soil sensors will soon be installed to schedule watering of parks and street planting.

Pulse of the City was launched last November; it allows users with GPS-enabled smartphones to check bus-arrival times and works as an augmented-reality device to give ‘what’s-on’ information about city venues, offers at shops and general city information. Moreover, it works as a problem-reporting system: users can take a photo of, for example, a hole in the road and their phone will send the picture along with a location tag to the relevant authority. 

Testbed systems based on the Santander model are currently being installed in Guildford, Lübeck and Belgrade.