(a) The following requirements apply to all bridges across the Piscataqua River:
(1) Public vessels of the United States, commercial vessels over 100 gross tons, inbound ferry service vessels and inbound commercial fishing vessels must be passed through the drawspan of each drawbridge as soon as possible. The opening signal from these vessels is four or more short blasts of a whistle, horn or a radio request.
(2) The owners of these bridges shall provide and keep in good legible condition clearance gauges for each draw with figures not less than 18 inches high designed, installed and maintained according to the provisions of § 118.160 of this chapter.
(3) Trains and locomotives shall be controlled so that any delay in opening the draw shall not exceed five minutes. However, if a train moving toward the bridge has crossed the home signal for the bridge before the signal requesting opening of the bridge is given, that train may continue across the bridge and must clear the bridge interlocks before stopping.
(b) The draw of the Memorial (US 1) bridge, mile 1.9, shall open on signal; except that from 15 May through 31 October, from 7 a.m. to 7 p.m., the draw need be opened only on the hour and half hour for recreational vessels and commercial vessels less than 100 gross tons except as provided in (a)(1).
(c) The draw of the Sarah M. Long (Route 1 Bypass) bridge, mile 2.5, shall open as follows:
(1) The main ship channel draw shall open on signal; except that from 15 May through 31 October, from 7 a.m. to 7 p.m., the draw need be opened only at quarter of and quarter after the hour for recreational vessels and commercial vessels less than 100 gross tons except as provided in (a)(1).