Odd you mention that....my small town (pop. ~4500) just spent the last few months replacing every street light with LED's. City council says cost/benefit analysis showed they'd pay for themselves within a couple of years compared to the old vapor lamps. The town's certainly not awash in money so it had to provide a decent return on investment to spend our limited capital.
If your town was running mercury vapor lamps (bluish) rather than HPS (orangey) the larger savings make the investment up front more attractive. HPS starts out a lot more efficient, as does MH.
The City & County of Denver is going all in on LED street lights. Then they can lay off employees like they did with the conversion to LED traffic lights. Job loss is the hidden cost of technological progress.
Denver’s night glow will turn from orange to white with 44,000 new LEDs
Utility crews will spend the next year installing new LED streetlights in Denver. The result: energy savings, better visibility — oh, and a different color of Denver.
www.denverpost.com