LEDs are very directional. Look at the before/after photos on this page. That’s not a twilight sky on the left, but light pollution.
http://cleantechnica.com/2013/09/12/worlds-largest-led-streetlight-retrofit-completed-in-los-angeles/

“The largest among those cities is San Diego, which will be replacing about 90 percent of its streetlights, roughly 35,000. The city is replacing its old low-pressure sodium lights – a common streetlight – with induction bulbs that use about 40 percent less energy. 16,500 have already been converted, and officials expect the transition to be finished by next spring.

Before the conversion, the city had been paying about $4.7 million a year to light its streets. When all 35,000 lights are replaced, that cost will drop to about $2.8 million a year, according to Tom Blair, deputy environmental services director for the City of San Diego.

And it’s not just energy costs that will go down. The old sodium bulbs typically had to be replaced every 3 or 4 years, while the new induction bulbs can last more than a decade. Blair says a set of induction bulbs were installed in downtown San Diego about 12 years ago and have yet to need replacement. “That’s a significant savings,” Blair says.”
http://www.theatlanticcities.com/technology/2012/04/secret-energy-drain-cities-streetlights/1856/

I stumbled across another site that listed ten or so cities that have switched to LEDs and have found the payback period to be 7 to 10 years based on electricity savings alone. Some cities were spending over 50% of their energy budget on street lights.

Replacing bulbs is an additional savings. Have to send out a truck with lift and crew. Sometime a squad car to manage traffic.

I also believe that fixture design and positioning needs to be considered more carefully. In so many places there are many more lights than are actually needed to illuminate the area, and fixtures are often poorly designed so that much of the light goes straight into the sky, into people’s eyes (glare), or is otherwise wasted. We don’t need more lighting, we need better lighting.

Not only would these things save even more energy, but it would also help to bring back the dark night skies we used to have. It’s quite sad to realize how many people these days have never really seen a true starry sky.