Route is misaligned in tdem

Can you explain with a little more detail?

It's really the coordinates and distance mesasure that end up out of whack. If i could get google earth to display incremental utm like the output from tdem, or if tdem would output reference lines in long/lat , i think i could fudge the rest without too much stress.

It appears you are referring to lat/long coordinates obtained in Trainz Surveyor. That would not be a good idea.

TransDEM maintains an accurate and static mapping between UTM and Trainz baseboards coordinates (christened "Trainz World Coordinates" or TWC by Auran/N3V). Both the UTM and TWC coordinate systems are two-dimensional, Cartesian and metric. For instance, when you move 14,400 m in one principal direction in the real world, you will find yourself exactly 20 baseboards further down in the same direction in the Trainz world on your TransDEM-generated map. 144 km will find you 200 baseboards further down (as long as we stay in the same UTM zone). This also allows you to build a route in stages, in separate modules, which you join together in Trainz and they will merge seamlessly.

How does TransDEM retain the static mapping between TWC and UTM when adding UTM tiles or vector data at a later stage? TransDEM leaves a footprint in the generated route, the Trainz World Origin object (WO). It positions the WO exactly in the center of one baseboard and assigns a pair of lat/long coordinates to it. Resolution here is limited, the Trainz lat/long notation only allows very low accuracy, but with the additional knowledge that the location is the exact center of a baseboard, TransDEM can fully restore the precise UTM location.

As a by-product, the original purpose of the Trainz WO as the anchor point for the solar features in Trainz, will also be fulfilled. And that's it about the WO.

**Trying to derive anything else from Trainz lat/long coordinates will definitely not work and only cause frustration.**
Firstly, there is no such thing as a single and universal coordinate system for our planet, neither in lat/long (aka geographic coordinates) nor in any of the map projections and their Cartesian coordinates.

As we all will know, the shape of the Earth isn't exactly a sphere, but for some applications sphere may suffice. Normally we will find an ellipsoid as the underlying geometric model of a coordinate system and many have been defined since the beginning of proper geodesy. They not only differ by their geometric parameters, but also by their position in relation to the prototype, the proper Earth, the "Geoid". Each of these spheres and ellipsoids comes with its own lat/long system and they are not compatible.

The combination of the geometric parameters of the sphere or ellipsoid and its relative position is called a "geodetic datum". If we know all the parameters of a given datum, we can convert it to a different datum. Many map tile servers, for instance, including Open Street Map, Microsoft Bing Maps, and Google Maps, use a spherical geodetic datum (and a standard Mercator projection on op of it) but since the datum parameters are well known, we can easily convert between datums and thus obtain ellipsoidal WGS84 coordinates, the geodetic datum used in TransDEM. WGS84 is the closest thing to a universal geodetic datum and you will quite often see lat/long based on WGS84. But there is no guarantee, you always have to look at the small print. For instance, USGS topo maps were produced with the NAD27 datum until less than a decade ago. They are now NAD83, which is very close to WGS84 (regarded as identical in TransDEM).

Unfortunately, we do not know anything about the geodetic datum of the WO and its celestial system in Trainz. Furthermore, we do not know anything about the map projection in Trainz in use to drive that celestial system. In the early years of Trainz people created one or two helper objects that are able read Trainz lat/long coordinates for any given baseboard location. By doing this they made an implicit but erroneous assumption: That Trainz lat/long coordinates would have an actual 1:1 counterpart in the real world, in particular WGS84. That is not the case! (I don't blame them. Geodetic datums are not general knowledge. You won't hear about them in school.)

The Trainz landscape is flat from a mathematical point of view, not a sphere or ellipsoid. Foundation Trainz coordinates are TWC, Trainz World Coordinates, as mentioned earlier. It therefore made a lot of sense for TransDEM to map UTM directly to TWC. The only reason why we also have lat/long in Trainz - as far as I understand - is to control the sun. Nothing more. Don't try to interpret it otherwise.