Lionel produced a fastrack book ending in 2016. Check ebay or Amazon.
The Title was Track and Power with year. It does cover y's crosses and switches.

There are a lot of books out there and would carry more complex layouts.
I have the 2014-2015 copy.

 

Thanks for that info. I actually got the pdf of the 2016-17 catalogue. Has more info in it than I've seen elsewhere for sure

 

Others may know but my suggestion is to download SCARM track planning S/W. It has Fastrack in it's database (free license for 100 pieces of track). It's mostly point and click ala MS-Windows apps with some quirks. Takes a bit to get used to. It won't tell you which track you need, but it will tell you whether a track plan will line up according to the FasTrack dimensions database.

Here's a sample in O-27...

 

Thanks. I've been using Scarm since before I had my set up. I've also used AnyRail and Rail Modeller for osx. They all still require you to do your own math despite carrying complete catalogs of the various types of track from different manufacturers. RailModeller for OSX will actually allow you to set a +/- threshold and do an auto complete but it's use is very limited. It still requires a mathematic approach to the track design to get a perfect fit. I know there's room for wiggle but I want to eliminate that with precise conversion tables and angles. If I wanted to run a turnout on one side, knowing the exact pieces on the opposite to match up where it's not symetrical in the first place.