The South Korean authorities are looking for a new innovative way to solve the increasing overloaded traffic with the related sound and air pollution. ZJA is approached to design a comfortable, clean and safe mode of transport, with a high level of aesthetics and urban planning.
An Elevated Light Rail Track (ELRT) is designed in a way that it can be implemented in all South Korean metropoles. The track is lifted about 15m and supported at 200 meters distances on slender columns. This to reduce the impact of the current ground level situation.
The span is made by a steel structure with an I-section shape. The web of the I-section is a large open truss system with on both sides at top (roof) and bottom (floor) the flanges made from steel 3-dimensional frame structures. The section is designed for a double track, one on each side of the web. To be able to create the required torsion capacity a double layer of diagonals is placed in the web.
Another strong reason for the double web layer is the ductile design that is created. This is the same for the 3D structure of the roof and floor. When an element fails the flow of forces can find an alternative route and prevents large damage and unsafe situations on and beneath the track.
The column supports are V-shaped to have a large span at ground level but reduces the main span at track level. Due to the high forces at the support locations here the steel I-section is increased in height to improve the efficient use of steel.
Using a cable structure is studied to support the self-weight, but an optimisation between steel weight, stiffness, maintenance and cost resulted in a structure with a pre-camber.
The building sequence is an important part of the scope. As in the final situation, also temporarily during construction the impact on the current ground floor activities must be minimized.
Many optimisation studies are done. For this a shared parametric model is used, made by ZJA and SIDstudio. Earthquake and wind and traffic dynamics are analysed in collaboration with IV-Infra.