Kurt, how long does the test go on? I'm considering writing a blog about it tomorrow if it's not too late. Thanks, Joe ________________________________ From: Canopus56 <canopus56@yahoo.com> To: Utah Astronomy List Serv <utah-astronomy@mailman.xmission.com> Sent: Sun, February 7, 2010 10:45:20 PM Subject: Re: [Utah-astronomy] Street Lights Two pics of two test areas: TestArea7 20100206 800 S 600 W Replace 250W Sodium unrecessed cobra head with 88W recessed cobra head http://www.slas.us/gallery2/main.php?g2_itemId=2991 TestArea6 20100206 900S 600W Replace 400W Halide with 200W Induction in acorn head http://www.slas.us/gallery2/main.php?g2_itemId=2994 General impressions - The design of the head is more important and what goes in it. The recessed cobra heads project light down into distinct pools without hazardous glare. The original sodium lamps project below the bottom of the cobra head in order to disperse unshielded light across 180 degrees and thus create driving hazard glare. For older drivers, nighttime glare is an important safety concern. In the eldery, nighttime glare causes eye strain and headaches. It was much easier to drive through those sections of the 800 South in test area 7 that had the fully recessed cobra heads with lower wattage because they produce pools of shielded light from above without any glare. Without straining against the glare from a projecting-type cobra head, it was easier to maintain relaxed awareness of the driving situation. Due to over-the-top glare from the use of acorn heads at very high density, the acorn heads in test area 6 created an unsafe driving condition for elderly drivers. This was due to the fact the acorn head design and not the type of lighting used. The standard acorn heads adopted by Salt Lake City and used, for example, in the Avenues, are inherently unsafe for elderly drivers. The acron heads place unshielded lights just above the horiztonal sight line of the driver's eyes but still within their central field-of-vision. A short drive through Test Areas 5 and 6 induced both noticeable eye strain and a slight headache. The overall lighting gave the unasethetic effect of Draper-prision-like lighting. Because of the lighting, Test Areas 5 and 6 are not I kind of place I would like to drive through or live in. The SLC acorn heads were adopted after a fairly good study on lighting by the City back in the 1990s that concluded that the recessed cobras were the best type of lighting. But the report and City adopted unshielded acorn heads from a false perception of economy - that unshielded acorn heads projected the most light over the largest areas - and therefore were the "cheapest". Clear Skies - Kurt _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com