Boston’s Big Dig tunnel is set to undergo a complete LED lighting retrofit, as many of its existing lights have prematurely corroded and the older fluorescent tube fixtures are failing at their support points due to design flaws. The $55 million retrofit will replace the fixtures with sealed LED lights that will save $2.5 million a year in electricity, and even more from the steep reduction in maintenance costs – not to mention providing peace of mind from falling debris.
When the lights were selected 10 years ago, LEDs were not yet hitting the market. The standard lighting fixtures at the time were 8-foot florescent lights which often need replacement, and they are housed in complex fixtures prone to water damage. Corrosive effects from salt water and galvanic effects from using dissimilar metals led to the premature failure of the supports, and because the seal clamps are so tight, every time a bulb is replaced the casing’s powder coating is prone to cracking from stress. One of the 100 pound fixtures has fallen into the roadway, and another 9,000 are temporally strapped with plastic zip ties.
The replacement plastic polymer-housed LED fixtures are permanently sealed, half the weight and will not (knocking on wood) corrode in wet environments. Not only will they use much less power they will not need maintenance for their 12-15 year expected lifespan. While the costs of replacements are high, LED technology is a jump in long-term cost savings and the retrofit may come close to paying for itself in energy and labor. Work to replace 25,000 existing lights in the I-90 and 93 tunnels will begin this spring and continue, mostly at night, for 18 months. The money will come from a $500 million dollar settlement received after a litany of problems during construction.
Via Boston Globe
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