Cal. Code Regs. tit. 8, § 7131 – Shaft Tracks.

(a) The tracks for the shaft conveyance in inclined shafts shall be made of steel or other metal of equal strength.
Exception: Wooden rails or skids may be used with a bucket when enlarging or deepening a shaft.
(b) Rails shall be well aligned and securely fastened in place.
(c) The connecting ends of rails shall be fastened together by use of splice bars or welds.
(d) Rail joints shall be supported adequately to prevent bending. It is recommended that rail joints be staggered for better stability.
(e) The track shall be maintained in good condition. Repairs, when needed, shall be made without unnecessary delay.