For purposes unrelated to railroading, I was reading this article, which pertains to the history of driving on the left or right side of the road. About half way into that article is a section regarding trains. This may be old news for you experienced folks, but it was news to me. I thought folks may be interested in this particular excerpt, if you're modeling C&NW:
In the USA and Canada, trains keep to the right, with one major exception: the Chicago and Northwestern Railroad. The line's construction was financed by British capital, which may have influenced the track plans. It may also be that the stations were arbitrarily placed all on one side of the tracks when the line was single-track, and when the second track was added it was impractical to change all the station alignments so the outbound track ended up on the left. (Don Howard, Eric Zimmerman) Another exception can be found in the approaches to New York City's Grand Central Station, which were run left-handed around 1900 because the new arrivals section of the terminal was built on the only available land, on the wrong side of the tracks. The crossing point was several miles north of the station, away from the worst congestion.
For the sake of trivia, it's worth mentioning that the "Union Pacific North Line" of Chicago's Metra that runs from Chicago to Kenosha, WI runs on the left as this stretch was the original run of the C&NW with depots all built on one side mentioned above. Each year millions of people ride those rails.
There are at least two places where the left-hand track on a steeply-graded line was the easier uphill grade, so traffic was routed accordingly. Cajon Pass and Weber Canyon are the ones I thought of immediately. Feel free to add to the list.
The NYC four track main was arranged passenger east/passenger west/freight east/freight west. The two center tracks were 'wrong way' to each other. This was done to prevent trains from running in the same direction on adjacent tracks.
In addition to the countries of the former British Empire, Japan operates multiple tracks by the left hand rule. This was probably a result of the use of British-built locomotives (with standard British control placement) on the first lines to be double tracked. As a direct result, multi-track mains in my garage run left-handed.
Chuck (Modeling Central Japan in September, 1964)