Construction, building and trade contractors, include plumbing and electricians, install and repair specific systems within residential and commercial, and industrial buildings. Heavy civil engineering trade contractors are often hired by governments to build or revamp roads, bridges, and highways. A trade job is any occupation typically requiring specialised skills learned through advanced training, rather than a 4 year college or university. Common types of career preparation for trades jobs include vocational training at a trade school, apprenticeship or on-the-job training.