Energy-efficient traffic-aware street lighting using autonomous networked sensors

• Main Author: Lau, Sei Ping
• Format: Dissertation
• Language: English
• Published: University of Southampton 2016

Street lighting is a ubiquitous utility. It does not only illuminate the streets during the night but also helps to prevent crime and traffic collisions. However, to sustain its operation is a heavy burden both financially and environmentally. Because of this, several initiatives have been proposed to reduce its energy consumption. However, most initiatives are mainly aimed at energy conservation and have given little consideration about the usefulness of street lighting. A Streetlight Usefulness Model, an evaluation metric used to measure the usefulness of street lighting to road users, is proposed. Using StreetlightSim, a real-time co-simulation environment developed as part of this research, the energy efficiency and usefulness of six existing street lighting schemes have been evaluated. Their performances were used as baseline results which later justified the proposal of Traffic-aware Lighting Scheme Management Network (TALiSMaN). Simulation results show that TALiSMaN can achieve comparable or improved usefulness (> 90%) to existing schemes, while consuming as little as 1 – 55% of the energy required by existing schemes. To consider the limitation of ‘off-grid’ streetlights – those powered locally by renewable energy, TALiSMaN has been enhanced with an energy demand predictor to ensure that a limited energy budget can be used fairly throughout the whole night. This enhanced scheme is known as TALiSMaN-Green. Combined with knowledge of the amount of energy stored, and predicting sunrise times, TALiSMaN-Green modulates the lighting levels requested by TALiSMaN if the energy stored is predicted to be insufficient for an entire night. The results show that this scheme extends the operational lifetime of solar-powered streetlights from 2 to 16 hours. Evaluated with real traffic flow and solar readings, TALiSMaN-Green can maintain streetlight usefulness at 60 – 80% (mean = 73% with standard deviation of 9%). In comparison, the streetlight usefulness of TALiSMaN was reduced to below 30%.