The draw of the Northern Avenue Bridge, mile 0.1, at Boston, shall operate as follows:
(a) From May 1 through October 31, the draw 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 a two-hour advance notice is given by calling the number posted at the bridge.
(b) From November 1 through April 30, the draw shall open on signal from 7 a.m. to 3 p.m. From 3 p.m. to 7 a.m. the draw shall open on signal if at least a twenty-four hours advance notice is given by calling the number posted at the bridge. [CGD01-00-234, 66 FR 10817, Feb. 20, 2001]