Abstract: An underfloor cable tray assembly is combined with a raised floor and is intermediate the raised floor and a subfloor which supports both in an electrical equipment room. Uniformly spaced stanchions support raised floor joists and floor panels to establish the raised floor for the equipment. Instead of having the communication cables strung without order on the subfloor, the underfloor cable tray assembly is provided to route such communication cables in an orderly manner among the various pieces of equipment. The cable tray assembly is formed from modular cable tray sections having a U-shape in cross section and selected from straight sections, horizontal bends, horizontal tees, and crosses. Splice plates and threaded fasteners interconnect these selected cable tray sections to form the complete cable tray assembly.