236.410—Locking, hand-operated switch; requirements.
(a)
Each hand-operated switch in main track shall be locked either electrically or mechanically in normal position, except:
(3)
Where a signal is provided to govern train movements from the auxiliary track to the signaled track; or
(4)
On a signaled siding without intermediate signals where the maximum authorized speed on the siding does not exceed 30 miles per hour.
(b)
Approach or time locking shall be provided and locking may be released either automatically, or by the control operator, but only after the control circuits of signals governing movement in either direction over the switch and which display aspects with indications more favorable than “proceed at restricted speed” have been opened directly or by shunting of track circuit.
(c)
Where a signal is used in lieu of electric or mechanical lock to govern movements from auxiliary track to signaled track, the signal shall not display an aspect to proceed until after the control circuits of signals governing movement on main track in either direction over the switch have been opened, and either the approach locking circuits to the switch are unoccupied or a predetermined time interval has expired.
Code of Federal Regulations
[33 FR 19684, Dec. 25, 1968, as amended at 49 FR 3386, Jan. 26, 1984; 75 FR 2699, Jan. 15, 2010]