Section 401.52 - Limit of approach to a bridge(a) No vessel shall pass the limit of approach sign at any movable bridge until the bridge is in a fully open position and the signal light shows green.(b) No vessel shall pass the limit of approach sign at the twin railway bridges on the South Shore Canal at Kahnawake, until both bridges are in a fully open position and both signal lights show green.39 FR 10900, Mar. 22, 1974, as amended at 61 FR 19551, May 2, 1996; 65 FR 52914 , Aug. 31, 2000; 79 FR 12660 , Mar. 6, 2014