biologist, said the concern
was that lighting for the bridge would disorient loggerhead hatchlings away
from the ocean. "We knew the existing 'glow' of the cities was already
causing disorientation problems as far away as Dewees Island, which is
several miles to the north of Charleston," Murphy said, "and did not want
to increase the light problem even more."
To learn more about sea turtles on the South Carolina coast, check the new
site. There can be found the latest information on conservation
efforts, easy access to sighting forms as well as video of turtles in their
natural habitat. Also, find out more about the Ravenel Bridge at
Murphy said the lead role to control the lights on the bridge came from
U.S. Fish and Wildlife Service biologist Paula Sisson. She knew a similar
cable-stayed bridge under construction in Brunswick, Ga., the Sidney Lanier
Bridge, was considered for an aesthetic light system. Because that bridge
is only a few miles from a known nesting site, the question of lighting
impacts on nesting sea turtles was being raised there, but has yet to be
Ravenel Bridge engineers utilized local ordinances on beachfront lighting
and turtles as their guide to resolving the turtle issue.
The Endangered Species Act requires federal agencies to consult with the
U.S. Fish and Wildlife Service to ensure they are not undertaking, funding,
permitting, or authorizing actions likely to jeopardize the continued
existence of listed species or destroy or adversely modify designated
critical habitat. The Federal Highway Administration was the lead federal
agency with funding support, and the Army Corps of Engineers was the lead
Timers were added to the bridge system to eliminate impacts to sea turtles.
During the nesting and hatching season (May through October), lights will
turn off at 10 p.m. The remainder of the year they turn off at midnight,
based on public input for energy conservation. During special occasions,
such as the Spoleto Festival, the city might request the lights to remain
on a little longer.
The wattage of the system was reduced during the design, and the light
circuits can be operated independently to "dim" or reduce the total wattage
being used at a given time.
In the interchanges at each end of the bridge, tall "high-mast" light poles
are preferred by the S.C. Department of Transportation because they can be
maintained without getting into traffic lanes. On the Ravenel Bridge, the
Department of Transportation opted for standard-height streetlights that
reduced both the amount of light spilling into adjacent neighborhoods and
the distance from which these lights could be seen. In addition, the bridge
design incorporated reflective road signs as opposed to electrical ones to
help reduce the overall amount of light. Murphy said the towers on the
bridge could have had a significant adverse impact on loggerhead
hatchlings, "Because it's so high, you can really see it a long way off."
- Written by Brett Witt -
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