Seattle Puts Street Lights to the Test

Street lights in Seattle

Which kind of street light do you like better — traditional yellow street lights or new LED street lights? Recent articles in The New York Times and LEDs Magazine covered how a group of power companies, consultants, the Department of Energy, Seattle Dept. of Transportation and Seattle City Light paid 400 people about $40 each to test which they prefer.  The test wasn’t really just for looks.  Utilities and municipalities have serious questions about what works better for saving energy and replacement costs versus safety and the area’s look and feel.

The test seemed to be well thought out, testing street lighting from both a vehicle and pedestrian point of view.  A 15-block stretch of 15th Avenue in the Ballard section of Seattle was closed to traffic so that test SUVs could drive up and down at 35 miles per hour with survey participants. The SUVs were fitted with light sensors, cameras, and a GPS system linked to a customized control system.  The participants were asked to push a button when they spotted small 7×7-in objects placed beside the road. GPS allowed the system to capture the exact location for each detected object for analysis.  The test was followed by a qualitative survey that asked participants to walk the test area under the lights. The written survey asked about the quality of the light, glare, feeling of safety, and other issues.

What about the weather and other variables?  Over the course of the night, lights were dimmed to test how low the lights could safely go before it impacted visibility.  Because of the frequently rainy Seattle weather, the organizers tested variations with the lights to mimic wet conditions.  Unfortunately, the weather was spectacular that particular night, so the organizers had to wet down the streets to get the typically wet Seattle effect.

What were the results?  Neither article had the results, but the organizers have also tested in Anchorage, San Diego and San Jose.  We’ll keep our eyes out for results or if you know where they are, feel free to comment.

Fun Facts:

  • Seattle has already installed 20,000 LED lights, second in the US only to Los Angeles, California, and the short-term goal is to install 41,000 LED lights.
  • There are 26.5 million street lights across the US that use $2 billion worth of energy each year.

For Further Reading:

The New York Times, Seattle Gets the Street View on the Quality of Its Lights,

LEDs Magazine, Seattle LED street-light tests focus on visibility and efficiency (Updated),



This entry was posted in LED light bulb, Solid State Lighting, Uncategorized and tagged , , by Beth. Bookmark the permalink.

About Beth

It seems like LEDs are in everything these days – backlighting everything from your mobile phone, Apple iPad and flat screen HDTV to traffic lights, light bulbs and even the kitchen sink. But, making LEDs is a complex process that begins with the creation of sapphire. Not the pretty blue gemstone, but large commercial crystals that can weigh as much as 400 lbs. Once these large sapphire crystals are grown into boules and cooled, they’re cut into cores, cut further into flat circular wafers, polished and then used to grow LEDs. About 85 percent of HB-LEDs (high brightness) are grown on sapphire. There’s not that much information out there about the process. This blog is meant to shed some light (excuse the pun) on sapphire, LEDs and the industry that is devoted to making our lives just a little brighter. In the months ahead, we’ll tackle some topics that will help you understand a little more about sapphire and LED industry. Here’s a sample of what we’ll cover in the coming months: • Growing sapphire • For a wafer, size matters • Quality - When sapphire wafers go bad • LED light bulbs • Market & myths • Interviews with industry shining stars • Reports from industry events • Current events in perspective Please join us each week to learn more about sapphire and the LED market. We look forward to seeing you.

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