Factory processes and levels of automation vary among companies, but typically, the factory building process is organized like an assembly-line production. As the building or module is assembled, it moves along the line from one workstation to the next. It can be rolled, lifted by crane or pulled forward along the line. More time-consuming and specialized work such as the construction of trusses, doorframes, kitchen cabinets, or pipe sub-assemblies, for instance, are usually fabricated away from the assembly line. Wherever possible, the construction of the buildings is done at ergonomic heights for optimized working positions.