Idle Lights Not Good for the Environment

Cut the Queues to cut CO2

16 April 2008

Cutting queuing time by just one minute per day on three major roads leading into a city could save more CO2 than switching off 2000 streetlights across a county, AA research has found.

Needless waste

The AA is concerned that re-phasing traffic lights, uncoordinated road works and certain "traffic calming" measures lead to cars idling longer and therefore pumping out more CO2. Fuel economy testing for the AA's Fuel for Thought campaign has found that 1000 petrol cars with warmed-up engines, each losing an average of 0.72 litres of fuel an hour idling, needlessly waste 28.32kg of CO2 each minute they are held up. A litre of petrol produces 2.36kg of CO2.

Just one minute a day

With a traffic flow of 20,8001vehicles on the average English city A-road, just three main roads generate annually over 645 tonnes of extra CO2 - if those vehicles are brought to a halt for just one minute each day anywhere along the route. This compares with the 590 tonnes of CO2 Buckinghamshire County Council said it would save by switching off 2000 streetlights2.

Keep the Traffic moving

"Our latest AA Fuel for Thought research reveals the massive CO2 benefits of keeping the traffic moving. The Highway Agency's traffic officers are helping to reduce the environmental impact of queuing traffic but more could be done by other highway authorities. Stationary traffic or idling longer at the lights is not good for the environment, so we need a concerted effort to reduce congestion," says Edmund King, the AA's president.

As a benchmark of needlessly lost CO2, one thousand cars held up for 10 seconds every working day while heading to and from work produce enough extra carbon dioxide to fill three and a half squash courts 3.

Councils should be accountable

King adds: "Current council policies to reduce CO2 focus on the car user rather than on what the council could do. So in terms of parking policy, residents with cars are penalised for the size of their engine (Richmond) or the length of their car (Norwich). Drivers also lose out with congestion charging (London), picked on for their car's tax band, or when streetlights are turned off (Buckinghamshire). Councils should be accountable for CO2 reduction, by upgrading gridlocked junctions, coordinating roadworks and reducing waiting times at traffic lights.

"Councils need to be measured on traffic efficiency and, if residents agree to environmental taxes or having their streetlights turned off, the money generated should be spent on improving roads rather than propping up town hall finances."

AA research

For cars with warmed-up engines, AA Fuel for Thought experts found fuel consumption while standing still was:

Small petrol car – 0.66 litres per hour
Medium petrol car – 0.78 litres per hour
Average petrol car – 0.72 litres per hour

Small diesel car – 0.36 litres per hour
Medium diesel car – 0.54 litres per hour
Average diesel car – 0.45 litres per hour

Note to Editors

1 Road Statistics 2006: Traffic, Speeds and Congestion – table1.3, Department for Transport


3 The average petrol car, consuming 0.72 litres of petrol per hour and each litre producing 2.36kg of CO2, produces 0.0047kg of CO2 every 10 seconds. 1000 cars standing still for 10 seconds produce 4.7 kg of CO2. Delayed both ways, five days a week and 48 weeks a year, they produce 2.256 tonnes of CO2 emitted while going nowhere.

With one ton of CO2 occupying a volume of 556.2m3, two and quarter tonnes fills 1254.79m3.


16 April 2008