Some quotes I have found from other cities about harsh lights and specifically acorn lights that are improperly illuminated.
" Lower lighting casts less of a shadow and makes pedestrians more visible. She said the City’s acorn lights are prismatic and cause glare. They are not fullcut-off and it is a problem. Businesses and residents must bring all lights into compliance within 3 years.
Don Kaltschmidt said when he got on the committee he thought they had a good diverse group. He asked the group what they were trying to accomplish and they educated him to the problem of glare and night glow. He said he wished he knew about this before he built his lot and he would have done it right the first time. In his old dealership they had a lot of vandalism, but they’re not having problems at the new lot. The ordinance is common sense—it saves energy and cuts off glare. He said the full cut-off lighting is a good idea. He talked to other business people and it was well received. It will cost him about $60/pole to retro-fit his current lights."
An example from a university campus...
In addition to improving crosswalks and pathway safety, the lighting in these multi-use intersections and along campus paths needs to be carefully planned. Currently, four acorn lights mark each crosswalk, but effectively only create more glare. From the driver's perspective one has just entered a city boulevard from a dark rural area, inciting drivers to speed up. Improvement in lighting is needed at these crosswalks, perhaps in the form of more directed lighting. This lighting must be carefully planned, because overly bright lighting is equally dangerous. When an area is very bright, it then becomes difficult to see outside of those areas of bright light into the darker areas around where pedestrians may be travelling. In the absence of bright light, vision may be limited, but it has “no sharp or definite boundary.”xxiiiInappropriate lighting plagues many businesses and institutions that invest in extensive outdoor lighting systems. Intuition suggests that outdoor lighting is for safety and therefore the brighter the better. However, as many schools, businesses, and individuals have discovered, bright lights can actually decrease safety. Many attributes of inappropriate lighting are apparent on the Middlebury College campus. For example, there could be better designed, down-directed lighting fixtures to replace the standard acorn fixtures. All light that is not aimed at directly at the ground is wasted light.xxivThis wasted light is not only inefficient, but also unsafe because light directed up from the ground hits pedestrians in the eyes, creating glare, and requiring eyes to constantly readjust to bright lights. This glare creates zones of intense brightness and deep shadow, thus providing a place for assailants to hide and wait for nighttime pedestrians.xxvOur eyes are versatile, but can only adjust to one light level at a time, and the period of time during adjustment is known as “transient adaptation.” When contrasts between brightly lit areas and dark shadows are more pronounced, eyes experience a temporary period of blindness. When bicycles and pedestrians share a path at night, visibility is paramount for avoiding accidents. Eyes can operate quite well at night, but when bright lights are installed the ability of our vision to adapt to the low light of nighttime is diminished.
Tests for glare and over-lit areas should be conducted to more effectively and safely light the campus. Preventative action including safe, efficient, and location-specific lighting should be taken to avoid accidents as the campus becomes more pedestrian."
http://home.epix.net/~ghonis/damon.htmOne city is looking at options to try and reduce the glare of their acorn lights.
Dark-sky compliant: with Lunar optics, glass shades (this will reduce upward glare toward the sky)
House-side shields if/as needed: 90, 120, or 180 degree shades (this will prevent glare on houses)
13’ pole with holophane Granville fixture (type and height)
50 watt high pressure sodium (HPS) –the mellow yellow light (bright enough, but not too bright)
Asymmetrical glass, type VII, IESNA Cutoff
Another example...
"We are on a three-year program of retrofitting city lights," said Hailey public works superintendent Allan Stowell. "We will replace 20 new heads this year." The lights, many of which can already be seen on Main Street, are more down cast with lower values. "It is also a public safety issue," Shay said. With the old "acorn" lights, there was a wide circle of darkness directly under the street lamps where light was most needed. The new lights offer a better use of the resource. The reason they have those acorns is because they look like hometown USA. They used to be incandescent lamps, not high-intensity-discharge lamps," Pauley said. "They look like hometown USA in the day, but at night you get blown away.
Hailey has budgeted about $50,000 over three years to convert the city lights so they have a shade, said Diane Shay, city planner.
Another example.... couldnt save the pics it was on a pdf and I dont know how to save pics. But basically the lights look exactly the same during the day. They are still acorn lights, but because of how they are designed, shielded acorn lights versus unshielded, they light the areas completely differently.
Changes in East Hampton, NY After many complaints about glare from their unshielded streetlights, the Village of East Hampton, NY set about replac-ing all of their existing “acorn” lights. The Village has replaced all 150 unshielded 250-watt high pressure sodium (HPS) fix-tures with 150-watt HPS shielded fixtures from Pennsylvania Globe and Gaslight. As shown in the before and after photos on the right, the new “Parklane” fixtures deliver more light to the street and sidewalk, and less light sideways and upward, and thanks to an opaque cap, limit glare and uplight....
They feature a clear glass globe, opaque cap, and
shielded design. Says Susan Harder, “not only is there no glare and
plenty of light on the ground, but the new lights have made our Village
beautiful at night—and now we can see the stars!”
I could go on and on... Apparently many places, like Tulsa, also once thought the Acorn Lights were a good idea. But now you see them trying to fix the problem that was inadvertantly created by them. There are solutions, but I would think it would be wise to install the right kind of lights in the first place rather than have to go back and spend extra money and effort later after we have created a lot of ugly. They can still be "pretty" Acorn Lights, but ones that are designed differently and or have the appropriate shielding and bulbs inside.
