Here is a few words about changing a light bulb.
A new lighting concept in schools, hospitals, offices

Hudnut LED Lighting brings the dynamics of daylight into classrooms, workplaces, hospitals creating a stimulating, ‘natural’ lighting ambiance and giving people personal control of their lighting. LED’s enhances people’s sense of well-being, motivation and performance.

How long does it take to change a light bulb in a shopping mall, a parking lot, a stadium?

Do you aware how much does it cost lighting maintenance for a school, a farm, a business center? You may think light bulb is cheap, sure true. But hiring someone, paying regularly replacement light bulbs for a company will not be that cheap if you add all the cost. Think about the cost of light bulb, and add all the bills you need to pay for changing a bulb only. Curious?

How long you can stop the traffic?
Have you think about causing a huge traffic jam?

The LED lights not only are a lot more energy efficient but they are easier to see. They also last longer than the old lights, so maintenance crews will spend less time (theoretically) tying up traffic to replace them. Electric Appliance Operating Cost Calculator can help you to get an estimate.