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Watts Going Down,
Energy efficiency on the George Roberts bridge.
Triple Bottom Line Benefits by Swapping Lightglobes

Assumptions - Case Study Results - Link to Spread Sheet
George Roberts bridge and the lights.
  • 80% reductions

  • Cost, greenhouse & energy

  • Triple Bottom Line benefits

  • Improve OHS

  • Improve Traffic Flow

  • Less Down Time

Saving Energy and Reducing Costs with Compact Fluorescent Lights

Townsville City Councils Citiworks Business Unit are saving energy and have reduced greenhouse gas emissions through the simple act of replacing incandescent light globes with compact fluorescent (link to Tip 3- Seven Sustainable Tips for Everyone).

Not only have Citiworks cut energy costs by 80%, but their maintenance costs have fallen dramatically due to the long life of compact fluorescents, and the reduced maintenance costs associated with removing entire strands of incandescent lights.

Supporting Sustainability through Appraisal and Change

George Roberts bridge and the lights.

The original 25W incandescent lights were first put up on George Roberts Bridge before 2000. The lights had a life span of about 3 months, and would be bulk-changed once a proportion had blown.

Replacing the incandescent lights incurred a maintenance costs of about $1,500 roughly every 4 months due to road closure and traffic signage requirements plus costs of about $2.25 per globe.

Citiworks critically appraised the system being used and sought alternatives to reduce energy and costs.

From this, they decided to install compact fluorescent globes that had previously been used in Flinders St East, but were no longer required due to the lighting upgrade of the street.

The 5W compact fluorescent globes, that are surrounded by a yellow sphere for added protection from the elements, were installed on the bridge during Christmas 2004.

The 5W compact fluorescents have an equal light output to a 25W traditional bulb, but use only a fifth of the energy, and have a considerably longer life span.

Whereas the incandescent globes failed after three to six months operation, and then required to be bulk-changed, the compact fluorescent lights, which had been in operation in Flinders St East since August 2001, are still largely in operation over three years later.

Not only do the new lights have a longer life span, only the blown bulbs have to be changed, thereby saving costs through a reduced need for signage and road closures.


  • Lights are more reliable and are suffer less down time. 80% reduction in energy cost - saves $54,960 per annum 80% less energy consumption - reduced by 26,280 kWh per annum
  • 80% reduction in greenhouse emissions - saves 28 tons per annum
  • Reduce peak energy demand by 6 kW
  • Reduce greenhouse emissions by 28 tons per annum
  • Improved traffic flow (formely required lane change for 1 day)
  • Saves $4,500 per annum in traffic management

The lights on George Roberts Bridge are on unmetered supply and the energy cost for these lights is determined by the Queensland Government and specified in the Queensland Government Gazette.

It is believed that these lights are categorised as Rate 3 in which case the cost to Main Roads is $9.16 per installed watt.

The economic and other benefits associated with this initiative have been modelled in a spread sheet and the information is available here.

Draft Assumptions      
number of lights
per watt fee
total annual energy fee
purchase cost each
setup traffic fee
replacement traffic fee
annual traffic fee
cost for 300 globes
annual replacements
annual replacement cost



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