Where oh where...

[FourEightFour]

I have a simple question, with probably a difficult answer. Where can one find a complete and concise guide on building a route? All of the information I have so far found is either outdated, in a foreign language, or supplanted with newer modeling/tech. I would like to build a 20 mile route set in the 1890's - early 1940's, so therefor everything will more or less have to be built from the ground up. I have driven the area many times, have lots of historical pictures, and have the entire set of I.C.C. Valuation maps of the track. I just need some direction in the railworks side of things.