It is for local highway authorities to decide whether or not to use light-emitting diode (LED) traffic signals. A number of LED products meeting UK requirements for traffic signals, as described in British Standard BS EN 12368, are available for highway authorities to install.
The Department for Transport has estimated the amount of energy used by conventional traffic signals to be of the order of 17-24 MW/hr. Changing to light-emitting diode traffic signals could potentially save 50-60 per cent. of this. Carbon dioxide emission reductions, operational costs and maintenance costs have not been estimated. Some of these depend on local energy agreements and maintenance practices and are for the local highway authority to determine.