It could be the map is really really huge and the program is choking on it. This was more of an issue with the older versions so if you haven't upgraded I recommend doing so.
Try trimming out the unneeded areas outside of your map-covered areas. To do this select the areas using the selection tool then click on the scissors. Follow the prompts Clicking will bring up a dialog box with options such as to KEEP the area outside the selected areas, which would make sense. Repeat until all you have left is the map-covered areas. This will reduce your export to a much more reasonable size.
Unneeded area were trimmed, and program was updated, but I still get the error. There are approximately 475 miles of tracks, I'm not sure if that is too big or not
Unneeded area were trimmed, and program was updated, but I still get the error. There are approximately 475 miles of tracks, I'm not sure if that is too big or not
475 miles is a big route. Try splitting this into parts and see if you can export a smaller section. What version of TD are you using? The current one is 2.6.3.0. This is the 64-bit version, by the way, and can handle large data sizes.