During March and April of this year, CTIO developed a collaborative effort with local public works authorities from La Serena, and representatives of a newly inaugurated shopping mall, to minimize light pollution from the mall's parking lot. This was a case in which everybody won.
During the first few weeks after the inauguration of the SeaGate Mall in northwest La Serena, it became apparent that there was a problem with the light fixtures illuminating their parking lot. Shoppers visiting the Mall could readily appreciate that there was excessive, poorly directed illumination. Drivers on the heavily traveled, high speed Pan American Highway nearby suffered impaired visibility coming into and leaving the region of glare -- an obvious safety hazard. From our offices on a hill several kilometers to the east, the effect of bad illumination practice was obvious: too much light was being directed or diffused skywards. (The International Dark Sky Association Website, http://www.darksky.org/ida/, is a good information resource for the non-astronomical problems caused by poor lighting.)
Following a long-term preventive and corrective plan, we approached the head of public works in La Serena, with whom we maintain very good relations. She immediately understood the situation, and together we met with the executives at the Mall. They were also very responsive, and investigated the cause of the problem. After consultation with their architects, it was found that the light fixtures had simply been wrongly installed. The individual housings were supposed to be pointed straight down. But due to misreading a drawing, they were inclined instead at 45º! At this point, the Mall management instituted an immediate fix of the problem at their expense, bringing in a truck with a cherry-picker from 500 miles away to access the fixtures.
The photo shows a fixture group being re-oriented. The result of correcting this geometrical mistake can be seen directly. The effects were immediate: parking lot illumination was improved, the hazard to highway drivers eliminated, and light pollution dramatically reduced. Our measurements from before and after the change indicate a 200× reduction in diffuse light in the first 50 meters above the Mall. Since so much of the light formerly diffused to the sky was now being sent to the ground, the mall was able to turn off some of the lights, thus further reducing light pollution and saving money on their electricity bill. The monetary savings are not trivial; electricity is expensive in Chile, and a shortage of hydropower induced by drought has resulted in additional incentives for large users to reduce consumption.
This successful experience has shown us once again that, while there is a general lack of awareness of lighting issues, there is plenty of willingness to help prevent or correct problems when the issues are explained. The SeaGate Mall example is a success for the community, for the business involved, and for astronomy in the IV Region.
Rene Mendez (firstname.lastname@example.org)
Maxime Boccas (email@example.com)