geophil wrote:
Obviously there are no rail lines there, but will this situation prevent me from creating a valid route in Trainz of another part of that DEM?
No, the DEM should be okay apart from the fault(y) area. You can either crop the DEM and reduce to valid regions or try to isolate those minima and replace them with valid values.
Now, -2147483648 decimal integer converts to 80000000 hex in a 32bit double word and such a pattern is usually a placeholder for a so-called "void" point, an undefined elevation.
Most DEM formats have a definition for such void points. In the case of ESRI Binary Grid and usage by USGS there appears to be a mixture of floating point and integer representations in the file which may cause confusion. I will have a closer look at that.