Because it was a strong metal.
Steel.
If that's a typo and you mean GEARed trains, then Trains work best on level ground - they don't do well climbing hills - because the friction of steel on steel is low. Geared trains ar not limited by friction.
Steel
7Adeed
Modern crossings are now cast from manganese steel rather than being fabricated from parts, this allows for less maintenance and stronger alloys to be used; these crossings allow faster trains to travel across them and trains which a greater weight.
It has 3 trains and they are all painted yellow.
They are made out of steel and hydrolicks
Becaus ist strong enough and inexpensive enough and light enough.
Railroad Tracksrails
Steel , Brass, Bronze, Copper,
steel and more steel
because steel is strong:)