Dublin City Council are proud of having been awarded the Sustainable Energy Ireland Award for their traffic signal conversion project in Dublin. In 2004 the City made a decision to use Alu Star LED traffic signals in an effort to become more energy efficient, prior to twhich they operated traffic signals using 55W halogen lamps. With nearly 700 sets of traffic signals in the city, a typical junction like O’Connell Bridge South has 34 signal heads with each group having a wattage of 60 Watt. This results in a load of 2kW for this single intersection. The annual energy costs for the entire traffic signal network amounted to more than € 200,000 and this does not include the preventive halogen bulb replacement costs every six months.

Brendan O’Brien, head of the Dublin City Council Traffic Department, explains:

“In 2004 we invested approx. € 200,000 in 400 new LED signals. Our major objective was to benefit from the advantages LEDs offer in comparison to the halogen lamps we used so far. Elimination of phantom light, the monitoring of signal head operation, the compatibility with the existing traffic controllers, and energy savings were our main expectations, all of which were impressively fulfilled. The annual costs savings on electricity for the 400 signal heads amounts to € 15,400. Another € 16,800 are saved as re-lamping and maintenance are no longer necessary. This makes € 32,200 annual savings for 400 signal units, which results in € 322,000 over the minimum 10 year LED life-cycle.”

Other findings of the Dublin case study are potential cost savings over 10 year minimum life for Dublin City region (7000 signals) of approx. € 5.6 million, a nationwide implementation in Ireland (approx. 15,000 traffic signals) would result in up to € 12m in savings.

Furthermore, LEDs also result in a positive effect on the environment. In 2004, 1kWh of electricity was responsible for 651g of CO₂ (Energy in Ireland , 2005). The above energy savings represent an annual saving of 91 Tonnes of CO₂ and a saving of 910 tonnes over the ten-year life of the LED’s.

Dublin has recognised the benefits from converting to LED technology which will see all new intersections in the future equipped with LED signals and thus serve as a good example for other Irish cities.