Triple-deck expressways are a modern transportation concept developed to manage heavy traffic congestion in highly populated urban areas where expanding roads horizontally is difficult. This system includes three vertically arranged levels of transport corridors within the same route. These levels may accommodate high-speed vehicle lanes, metro or railway lines, and local service roads. By utilising vertical space efficiently, triple-deck expressways increase road capacity, decrease travel time, and make better use of limited land. They are typically built using reinforced or prestressed concrete along with steel composite structures, supported by advanced foundation and seismic-resistant designs. Although the initial construction cost is high, such expressways provide a sustainable and long-term solution for improving urban transportation systems.