Laborers may be skilled or unskilled workers with duties as varied as clearing timber and brush, removing demolished materials from a job site, placing and vibrating concrete, landscaping, installing pipe, handling the materials for other trades workers or using explosives to demolish buildings. Laborers are needed on all types of construction projects such as highways, bridges, tunnels, large buildings, sanitation, and residential, and perform work for the duration of the project. A laborer must know how to work with his or her hands and with power tools run by gasoline, electricity, and compressed air. Other tools used include pavement breakers, rammers, pumps, compressors, lasers, and vibrators.