How did the geography effect the construction of the transcontinental railroad?

Answer 1

How does geography affect the construction..

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Right, that's the English corrected by the first answer; now the answer to the actual question! :-)

I don't know that line's specifics but as a general rule, Geography affects all Civil-engineering in one way or another.

Railways need modest gradients (1 in 100 is fairly steep, 1 in 50 unusually so, for a railway). So that means, in hilly areas, a lot of earthworks - cuttings, tunnels and embankments - to maintain as even and gentle a gradient profile as practicable and economical. They used valleys to help pass through mountain ranges, perhaps with tunnels through the summit ridges.

In high latitudes / altitudes, the line may need protection from snow and avalanches, as far as possible.

Points and signals are vulnerable to icing up.

Rivers and estuaries must be crossed - may need sizeable bridges. The railway must be kept above flood levels as much as possible. The "formation" (track roadway) has to be reasonably resistant to flowing or static floodwater.

Soft ground - peat-bogs and the like - needs special attention, as does permafrost.

Cuttings and hill-side terraces present landslip risks to be allowed for as far as possible.

In steam days, the fire risk in forests was a problem. It was too on the timber trestle viaducts typical of early American railways: many such bridges were destroyed by fire, flood, insect attack and decay. Steam locomotives also need regular access to water - I don't know if the British practice of troughs between the rails on level stretches of the main lines to allow picking up water at speed was also an American practice.

At a continental scale the sheer remoteness of much of the route presented problems in building and maintaining the line. Putting a railway through remote virgin forests in mountain ranges was a tremendous feat in the days of pick-and-shovel: even just surveying the route for the line was a major expedition.