Answer:
Wood and Iron
Explanation:
To built railroad tracks it is required to obtain woods from forests for the wooden rail ties. Wooden ties (sleepers) were used in tracks to hold long iron tracks in its place when a train moves above it. Historically, wooden ties used at the beginning of railroad expansion, which shipped from forest areas to the construction sites. Iron placed an important in building the tracks because of its quality of being very strong, holding weight, and resisting heat.
