The center line of any track, except a main track or a passing track, parallel and adjacent to a main track or a passing track, shall be at least fifteen feet from the center line of such main track or passing track; provided, where a passing track is adjacent to and at least fifteen feet distant from the main track, any other track may be constructed adjacent to such passing track with clearance of not less than fourteen feet.
Conn. Agencies Regs. § 13b-17-177