The challenge
The city of Coventry in the English midlands wanted better public lighting, for less money.
Modernising street lighting was part of Coventry City Council’s efforts to improve its roads and pavements, by bringing the lighting in all parts of the city up to a consistently high quality, in line with the latest European standards. It would also make the city’s 340,000 inhabitants safer at night by reducing accidents, crime and the fear of crime.
At the same time, Coventry wanted to get its electricity bill for public lighting down, cutting costs for taxpayers and freeing up funds for other projects. The target was a 38% reduction in energy consumption.
The plan
In August 2010 the city signed a £250 million (€320 million) 25-year private finance initiative (PFI) deal with contractor Balfour Beatty to replace most of its street lights, with the help of a £64 million (€83 million) grant from the UK’s Department of Transport.
Balfour Beatty – which looks after hundreds of thousands of streetlights around the UK under PFI arrangements – agreed to design, install and maintain a new system for Coventry that provides better quality light, uses less electricity, and can be automatically dimmed for further savings.
The project kicked off in November 2010, beginning with a five-year investment period during which the main work of design and installation took place. The contract also covers maintenance for a further 20 years, including electrical testing, structural inspections, lamp replacements and cleaning.
Lindsley Harvard, the councillor in charge of city services at the time the project began, said he wanted Coventry’s new street lighting to be “the envy of other cities” and deliver “significant savings on our energy bills”.
The Solution
The new lighting, designed in accordance with the council’s specifications, covers Coventry’s residential roads, minor and major traffic routes, city centre, car parks, subways, parks and other public areas.
Balfour Beatty has now installed a total of 26,000 new street light columns and lanterns, and replaced 6,500 illuminated traffic signs and bollards with LED versions (or in a few cases removed the lights from them). 5,000 columns that were less than five years old have had their lights upgraded rather than being completely replaced.
The lighting equipment was supplied by Dutch manufacturer Philips and UK firms Orangetek, Designplan and Simmonsigns. The control system was supplied by UK-based Mayrise Systems (which has since become part of Yotta), using wireless remote monitoring technology from Telensa, which is also based in the UK.
Where possible, lights have been left in the same positions as before, but in some cases they have been moved, changed in height, or had extra lanterns added to existing columns, to provide the right levels of light.
Residential streets have mainly been lit with white light, which renders colours clearly, making it easier to recognise cars and people, and creating a more comfortable atmosphere. The lights on a typical street use 45W or 60W lamps on six-metre columns, while wider roads have 90W lamps on eight-metre columns.
Busier traffic routes use brighter lights on higher columns: 150W at 10 metres, or 250W at 12 metres. These routes use different lamps that give a more yellowish light, but are more efficient.
Seventy-five high masts light the ring road that circles the city centre. In the centre itself, 18 high masts replace 200 standard light columns, reducing street clutter and using less energy.
The lights are designed to direct light downwards, to ensure light is not wasted, and to minimise any spillage of light on to private property or into the night sky.
A big advantage of the new lights is that they can be dimmed automatically when roads are quiet. The introduction of dimming meant the council had to balance its aim of cutting energy consumption with reducing crime and the fear of crime. To get this balance right, it conducted trials and assessments over three years on the impact of dimming.
Coventry is believed to be the first city in the UK, and one of the first in the world, to have installed a central management system (CMS) to remotely monitor and control its street lights. Wireless communication nodes attached to individual lights link them to a network of base stations, which in turn are connected to computers at the command centre.
The CMS controls dimming, and tracks the operation of all the lights, recording how much energy they use and detecting signs of faults early. This means lights can be fixed before they even go out, so it is longer necessary for teams to scout the city looking for broken lamps. The system enables the Balfour Beatty team to respond quickly to failures, meeting demanding targets set by the council.
The result
Thanks to more efficient lighting and dimming, Coventry has achieved energy consumption and carbon dioxide emission reductions of 38% – hitting its original target. The total annual cost of the system to the taxpayer is lower than the cost of looking after street lighting before the PFI deal began, the council says.
More than five years on from the start of the project, the next step will be to harness the latest technology to make Coventry’s network of street lights smarter. Over the next three years, the city will add sensors to its street lights, so that the lighting infrastructure can begin to support other services such as security, parking and traffic control. The council is considering introducing motion sensors for footpaths, traffic counters, rain gauges, ground level temperature sensors and parking space monitors.
Councillor Rachel Lancaster current Cabinet Member for Public service is delighted with the high quality of lighting, she said “The roll out of the programme citywide has been completed without any issues due to an excellent working relationship with our contractors. The system is flexible and efficient, and residents in the city have been very complimentary, I believe it was the right choice for Coventry”.