Every trackage rights or joint trackage arrangement, Union Station agreement, crossing or interchange between railroads was documented by a contract or agreement negotiated and signed by the parties. Many use essentially the same "boilerplate" language, with specific details added, multiple times. Terms and conditions for different kinds of agreements became almost standardized. That served to simplify negotiations and give everyone a basic understanding of what an agreement included. Many of the points included in the trackage rights agreement between the NC&StL, the Memphis and Charleston and the East Tennessee and Georgia dated October 1, 1880 can be found in agreements negotiated many years later. In fact, many of the the Main and Supplemental agreement conditions contained in Southern Railway contract file No.9 are still in effect between Norfolk Southern and CSX between Stevenson, AL and Wauhatchie, TN today. (NC&StL trackage was used from Wauhatchie to Chattanooga by both the M&C and what became the AGS until the Southern built its own line, through the Lookout Mtn. tunnel.) Reading past the boilerplate we find very specific details about what is covered.
The second example in the Google Drive file illustrates the kinds of maps or drawings attached to some agreements. It is from a 1948 agreement between the Southern and the NC&StL for Howell Jct in Atlanta. Here, the details are all important; which railroad was responsible for every signal, crossing and turnout, which controlled the crossing, etc. Howell i particularly interesting because of its complexity and that there were individual agreements covering the NC&StL (W&A), Seaboard and Southern. The agreement pages were scanned in bound books so they are not "pretty" but include the entire agreement. The Howell Jct. drawing was a fold out attachment that was unbound to make a high quality copy that could be published if someone wrote a "TIES" or L&NHS magazine article on the subject.
Although only a small number of agreements have been scanned completely, the SRHA archives contain approximately 1,203 different examples. The Southern accumulated and bound contracts in books that were distributed to officials through the system. When each of twenty-six (known?) books were produced, a cumulative index was added that included every agreement in force at that time. When contracts expired or were cancelled, they were omitted from the index. The index from Volume XXII issued September 1, 1945 is the third document in the Google Drive file and provides an idea of the scope of the collection. (The first number in an entry is the volume that includes the agreement, the second number is the contract number.)
Scanning contracts and attachments is an on-going task for archives volunteers.