Hi!  I work in a factory.  What do you do?
Large factories often are located where they have access to multiple modes of transportation. Railways, highways, and water transport are important to the business' success.
I agree.  There are many large roads near this factory.  What do you do for a living?
Factories often use rail transport to transfer goods on wheeled vehicles running on tracks.
I agree.  I've seen that type used.
History of rail transport
The history of rail transport began in 6th century BC in Ancient Greece. It can be divided up into several discrete periods defined by the principal means of track material and motive power used.
Ancient systems.
Evidence indicates that there was 6 to 8.5 km long "Diolkos" paved trackway, which transported boats across the Isthmus of Corinth in Greece from around 600 BC. Wheeled vehicles pulled by men and animals ran in grooves in limestone, which provided the track element, preventing the wagons
workshops".
Most modern factories have large warehouses or warehouse-like facilities that contain heavy equipment used for assembly line production. Large factories tend to be located with access to multiple modes of transportation, with some having rail, highway and water loading and unloading facilities. 
Factories may either make discrete products or some type of material continuously produced such as chemicals, pulp and paper, or refined oil products. Factories manufacturing chemicals are often called "plants" and may have most of their equipment – tanks, pressure vessels