Willow Avenue, the border between Fresno and Clovis is interesting. There are four lights at each intersection, and now two are LEDs, and two are sodium.
LED has a few advantages over the existing high pressure sodium lights. The most obvious one is color. The sodium lights are your standard yellowy-orange lamps that make it very difficult to see colors at night. LED's, on the other hand, are very white.
At this intersection, you can see the lights mounted on the traffic polls have been switched. All the other lights are of the older kind

From my observation, the LED lights appear to be brighter than what they replaced. This is a very good thing, as the street lights here can be placed quite far apart. At intersections, the brighter light helps make pedestrians more visible. The better color clarity also makes it easier to distinguish what's in the crosswalk.
The regular street lights are very yellow

There are a few other advantages to, besides color, and in this case, light output (light output will vary based on what model the city buys).
-Energy efficient. It's not a huge savings, because the old sodium lights are pretty efficient themselves, but every bit helps.
-Longer lifespan. LED is much more expensive than the existing installations, but is supposed to have a longer life. The savings in labor should be enough to justify the switch, along with the energy savings
-Better light distribution. The LED lights are more focused, unlike the sodium ones which have three distinct bright spots, and then darker areas. The older lights have glare and create shadows, as seen in this comparison.
LED lights provide a more uniform coverage

I'm excited to see the new lights around Clovis. Hopefully the savings mean that they can continue the transition throughout the year.
The intersection has been done, and is very well lit, but there are thousands and thousands of street lights in the city. If you like the sodium lights, don't worry, you'll be seeing them for a very long time

One other thing I'd like to see the city experiment with are lights with solar panels, but that's really something that PG&E has to push through. Maybe next year.
LED street lights would be cheaper and better.
ReplyDeleteLED Grow Lights
Hi all,
ReplyDeleteLED street light is a great cost-cutting technique that will save money for decades to come. The LED street lights generate a clean, low-glare light, which provides improved visibility over the traditional streetlights. The superiority of LED street light becomes unavoidable when environmental advantage is added to their extremely long life. Thank you.
Led Tunnel Light
The L.E.D. lights that Clovis has installed represent a gross step backwards in municipal street lighting when gauged against shielded and modern designs of high pressure sodium lighting. Not only do L.E.D. bulbs produce a very harsh and sharp light, but another issue is that the light they omit is directional in nature, much like searchlights. The problem with this nature is that L.E.D.s mostly light whatever they're pointed directly at; that's good for a flashlight, but bad for a streetlamp. This is because in addition to brightly illuminating the area underneath them, Sodium Vapor lamps cast an ambient light on the surrounding area, which --- with two lines of working streetlamps --- does wonders to illuminate not only roads, but much of the surrounding area. LEDs would brightly illuminate a skinny corridor, which isn't good for an open area. Having personally walked down sidewalks illuminated at night by Sodium Vapor lamps, I'm not too keen on the idea of walking in the middle an inky-black darkness, alongside a brightly-lit road with fast-moving traffic.
ReplyDeleteThats not necessarily true. Properly designed streetlights do spread an even light. In fat it sodium lights that create harsh shadows.
DeleteCompare the shadows on this comparison page
http://www.recycletechno.com/led.htm
Heres one that shows them being mostly even
http://www.cityofboston.gov/publicworks/lighting/led.asp
Heres one last one
http://ledlightreviews.files.wordpress.com/2009/08/led-vs-hps-betaled1.jpg?w=460&h=179
The problem in Clovis is streetlights are way too far apart. The good news is newer streets seem to have them closer together. Larger streets anyway, not residential ones.
From my experience in Clovis, the LEDs are better