The city has been installing them since 2009, here’s the latest efforts, plus the pros and cons.
TO: Mayor Paul Soglin; All Alders
FROM: David C. Dryer, P.E. City Traffic Engineer
SUBJECT: LED Streetlighting Implementation Madison, WIThe City of Madison will install nearly 400 new streetlights using LED (light emitting diode) technology in 2011. The City first began using LED lights in 2009. This was on a very limited basis, primarily on Highway 30, just east of E Washington Ave. Since then, the technology has rapidly improved, and many major light fixture manufacturers have added LED fixture options.
The City received proposals in April representing 10 different fixture manufacturers. The review of these options included measuring light output and light patterns from sample fixtures installed at the City’s test site.
The LED lights to be installed this year include the following streets:
1. Mineral Pt Rd: Racine to Grand Canyon
2. Whitney Way: Science Dr to South Hill
3. Langdon St: Park to Frances
4. Lake St: University Ave to Lake Mendota
5. N Franklin St
6. N Hancock St
7. N Blair St
8. E Mifflin: Webster to Blair
9. Outer Loop from E Washington Ave to State St
10. Several one block segments between the Capitol Concourse and Outer Loop
11. Northport Dr
12. Williamson St
13. South Point
14. Darbo Dr and
15. S Park St: Badger Rd to RidgewoodThe advantages of using LED lights compared with the high pressure sodium vapor (HPS) lights that have been the primary lamp type used for street lighting for the last 30 years include:
1. Approximately 40% energy savings for comparable performance
2. Longer life; the LED units should last for 10-15 years compared to 4-5 years for the HPS lamp
3. Reduced maintenance expense if the LED lasts as predicted
4. LEDs produce white light; color of objects can be better seen
5. Better light control, including less light spill (trespass) onto private properties—a function of the fixture type chosenThe limitations and concerns regarding LED lights include the following:
1. High initial cost. For some specialty fixture types, the LED cost is similar to HPS cost. But for the basic fixture type, LED fixtures cost at least three times more than HPS fixtures.
2. Longevity is not yet proven, given the newness of these fixtures.
The funding sources for LED fixtures this year include a Federal Energy Grant, street reconstruction funds, and special assessments.If you have questions or need further details, please contact Dan Dettmann ddettmann@cityofmadison.com, or 266-6536.
Personally, I’m not impressed with LED traffic signals. How often have you seen one at an intersection with half of the LED’s burnt out? These things aren’t lasting as long as the manufacturers claim, and the initial cost is much higher than traditional lamps. I’m all for energy savings, but the burnt out LED problem needs to be addressed.
Another drawback to the LED’s: Since they emit no heat, they can become and remain covered with snow in storms, and then the lights are invisible. I noticed this on some traffic lights on John Nolen Drive this past winter. Haven’t heard any ideas yet on how to deal with that; seems they’d each have to be cleared by hand, doesn’t it?
I’m glad to see the city jumping on board. The evidence really does point to better results with this technology. So long as a high-quality fixture is chosen, the concerns about reliability are a bit of a red herring. There are testing protocols in place industry-wide now to solve this. The traffic lights that are mentioned elsewhere in the comments are really a different beast. They are low-output, which causes the no-heat problem for snow. Higher output fixtures like these produce enough heat to melt snow in a matter of minutes (also, this isn’t much of a problem with streetlights, which point downwards). The issue of individual diodes failing in a traffic signal is a manufacturing quality issue. LED failure is actually a function of getting too dim, not of complete failure like you see in the traffic signals. That’s a failure of manufacturing elsewhere in the circuit board. Shouldn’t ever happen, but in the first generation of LED traffic signals it was relatively common due to the type of devices & the way they were mounted to the circuit boards. High output fixtures use LED packages that are surface mounted to metallic circuit boards to dissipate heat. These have a much lower failure rate. The installation on 30 looks great. I can’t wait to see these pop up elsewhere in the city.
Yeah, I noticed that too. Seems like it be dangerous if a driver can’t see a red light that well.