Technology and environmental issues

LED (light-emitting diode) traffic signal heads

Traffic signals have traditionally used halogen light bulbs, but recently more cost effective alternatives using LEDs have become available, and over the last five years we've proactively taken the opportunity to replace the old-style signal heads with LED signal heads, with the majority of sites now converted.

The advantages of using LED traffic lights are:

  • Much greater energy efficiency (something in the order of 66% can be achieved), which is good for the environment and produces a substantial reduction in the running costs of traffic signals
  • LED heads have a much longer lifetime between replacements, measured in years rather than months
  • Halogen signal heads suddenly fail at the end of their life, whereas the individual LEDs within each head will fail over a period of time, providing plenty of warning as to when to change the light - much safer than a sudden loss of a traffic signal
  • Brighter illumination with better contrast against direct sunlight

ELV (extra low voltage) traffic signal sites

Traffic signal sites have traditionally operated at the nominal mains voltage of 230v, and whilst there's less likelihood of receiving an electric shock from a traffic signal installation than the average household wiring, it's felt that operating traffic signal installations at a lower voltage of 48v offers the following benefits:

  • Reduces chances of an electric shock being received from an installation should a fault occur
  • When coupled with LED signal heads the energy saving increases to some 87%
  • Provides significant reductions in CO2 emissions due to lower power requirements, and reductions in raw material usage, resulting from the need for fewer street cables

Use of passively safe equipment

There are different options which can be employed, depending on circumstances, to minimise injury when a vehicle hits a traffic signal pole, including the use of passively safe equipment.

Passively safe poles will either shear on impact or fall in a predictable manner, and these two options are being considered for new or refurbished installation.