(225 ILCS 705/18.10)
(from Ch. 96 1/2, par. 1810)
When the main line track is used as a return conductor, both
rails shall be well-bonded at every joint, and one rail on secondary
haulage roads, when used as a return conductor, shall be bonded, unless
other equally efficient methods are used.
(Source: Laws 1953, p. 701.)