Code of Federal Regulations Title 33. Navigation and Navigable Waters § 33.117.915 Ashley River

(a) The draws of the US17 Highway Bridges (Ashley River Bridges), mile 2.4 and 2.5 at Charleston, SC shall open on signal;  except that, from 4 p.m. to 9 a.m. daily, the draws shall open only if at least 12 hours notice is given. The draws of either bridge shall open as soon as possible for the passage of vessels in an emergency involving danger to life or property.

(b) The draw of the Seaboard System Railroad bridge, mile 12.0 near Drayton Hall, shall open on signal from 7 a.m. to 11 p.m. From 11 p.m. to 7 a.m., the draw shall open on signal if at least three hours notice is given.