The Dunedin City Council is investigating the multimillion-dollar replacement of the city's 14,000 street light stock, including whether to install sensor systems so lights come on at different times in different areas of the city.
The city's street light stock is 20 to 25 years old and while the bulbs in a quarter of the lights were replaced each year, the glass housings for the bulbs were reaching the end of their life and would need to be replaced in the next few years, DCC roading maintenance engineer Peter Standring said.
Planning for the replacement had started, as it was a potentially expensive exercise, and the various new technologies available needed to be assessed before deciding what to use.
Investigations into more environmentally sound and financially efficient options for how the council ran its lighting stock had been under way for some time, including changing to LED light heads or other new technologies.
Various other operational options were being investigated, including the practicality of installing individual sensors on lights.
The lights are now switched on in groups via a pulse sent down the line by a sensor. A change could mean, for example, if Green Island was overcast and the light dim, the lights could come on earlier than in another suburb that was in full sun.
The idea was that there would be some cost savings if lights only came on when they were needed.
The plan was to do the work over the next two to three years, with a budget for the project included in the council's annual plan from 2014-15, Mr Standring said.
Street lighting costs the city about $1 million a year for the electricity and about $400,000 in bulb replacement and light maintenance. Installation and savings costings for the replacement lights had not been finalised, but new technologies were likely to be significantly expensive - in the millions of dollars - to install.
However, the cost would be balanced by savings over a period of years from reduced power usage.
The council would look to Auckland, which was about to roll out LED replacements, as part of its review, Mr Standring said.
