The purpose of this thesis was to plan, install, splice and measure an optical fiber backbone line for cables holding up to 864 fibers. The thesis also includes a section about physics behind fiber optics. The project started from planning the fiber line installation and then moved on to installation. Installation was the most time-consuming part of the project. After completing the installation the planning phase for splicing was started. This included team and work area management and planning the schedule for fiber splicing. The practical part of splicing consisted of work area preparation, fiber cable preparation and splicing. The measurement phase was started after agreement with the customers on the wave lengths and format of the...