Based on the Wiki sentence I've highlighted in blue, I think it must be this config tag. Does this mean I'm now an expert?
"adjust-height-to-ground-threshold
Any vertex with a model-space Z value less than this threshold number will be adjusted based on the height of the ground under that vertex. The math behind the adjustment is roughly as follows:
outputVertexPosition.z = modelVertexPosition.z + adjustHeightToGroundOffset + groundHeight
Typically, this height adjustment is used when building a bridge or similar structure - the bulk of the model is maintained at the actual spline height, but the bottom vertices of the legs or supporting pillars are dropped to ground height."
Without a diagram to show how it really works, most of the Wiki's description is lost on me as usual. Whatever this tag does, it won't be valid if the trainz-build of the bridge precedes the version of Trainz which first introduced the tag. Also, such edits will only be local to the user's own computer.
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