The Nam Wan tunnel is a 1.25 km long 3-lane highway tunnel. It has two separate tubes, 12 cross passages, and a portal building at each endIn the preliminary design phase COWI established an overall concept for the electrical and mechanical systems with emphasis on safety-related functions such as electric power supply, tunnel lighting, fire fighting, tunnel ventilation and smoke extraction. This overall concept was used as a basis for the Client’s detailed design.Later in the project COWI reviewed the Client’s detailed design of electrical and mechanical systems.The electrical and mechanical systems include the following: