Streetlights on M40 motorway left on for 24 hours a day for FOUR months

Not many, however, would see the point in lighting up a motorway in broad daylight.

Yet that is exactly what has been happening on a one-mile stretch of the M40 after a set of sensors went wrong.

Scroll down for more...

The section has been lit constantly since October because highway bosses failed to replace the faulty technology controlling more than 100 lamps.

Experts said the energy wasted so far would be enough to power a family home for four years.

It is also the equivalent, in terms of carbon emissions, of flying from London to New York and back ten times.

Steve Howard, of the Climate Group, which campaigns to cut greenhouse gases, said: "This type of thing fails the taxpayers and the planet.

"We all know that saving energy saves money and it is essential to reducing our carbon emissions and tackling climate change.

"It is irresponsible of the Highways Agency to leave these lights on for four months without fixing the problem."

The problem, which affects a stretch of the M40 between Uxbridge in North-West London and the M25, centres on a faulty feeder pillar which operates the bank of lights.

Light-sensitive cells in the pillar ordinarily automatically switch on the 250- watt lamps when night falls. The lights go off again at dawn.

When the sensory equipment worth £15,000 went wrong last year, highway bosses decided to switch the lights on permanently rather than risk them failing suddenly and causing an accident.

But despite a replacement pillar being ordered back in October, the Highways Agency still does not know when it will arrive.

David Coatham, a technical expert at the Institute of Lighting Engineers, said he put the cost of the electricity wasted over four months at £4,000.

Yesterday a spokesman for the Highways Agency insisted that taxpayers will not have to foot the bill.

He said the extra costs will be passed on to UK Highways, the private company contracted to repair and power the lamps.

"New equipment has been ordered and we are awaiting delivery," he added.

"The M40 is managed by UK Highways, working for the Highways Agency. UK Highways' existing contract covers the cost of the repair and power for the lights, without additional cost to the taxpayer.

"UK Highways have been told to investigate urgently to see whether there is an interim solution, which would allow the lights to be safely turned off during daylight hours, and to complete the repair as quickly as possible.

"Without the replacement part, the lights will not turn on or off automatically, so it was decided to keep them on for highwayuser safety reasons.

"The replacement part is custom built and must undergo testing before installation. It is not something that can be obtained 'off the shelf'."

Over the past few months, meanwhile, tens of thousands of street lamps have gone out after midnight, mostly in middleclass, suburban areas.

In Hampshire, 1,000 residents in Romsey are being left in the dark after midnight while similar trials have started in Gloucestershire, Essex and West Sussex.

Councils claim there is no evidence that street lights prevent crime or road accidents and say the sacrifice is needed to reduce carbon dioxide emissions.

The Government faced criticism from green groups earlier this month for failing to cut carbon emissions quickly enough.

Latest figures show that the UK's greenhouse gas output declined by only 0.5 per cent in 2006.