SYSTRA's innovation - U - shaped elevated structure
On the basis of summarizing the elevated structure forms of urban rail transit, through the joint efforts of multidisciplinary engineering experts, SYSTRA developed the U - shaped elevated structure, which is especially suitable for urban rail transit and complies with the needs of landscape and environmental protection for modern urban development. Its main characteristics are as follows:
1. Urban landscape to be improved
For the cross sections of traditional box structure, the depth of deck is usually between 1.5 m and 2.3 m. But for the U-shaped elevated structure, the depth of the structure under the rail (the thickness of the slab) is between 0.22 m and 0.35 m. Therefore, the track top level is reduced by 1.2 m to 2 m and, the lower part of the train is inside the u-shaped structure, which can help reducing the visual impact of the elevated structure in the urban landscape.
2. Good sound insulation effect
Since the trains run inside the u-shaped structure, the u-shaped structure's web plays a better sound insulation effect than the traditional sound insulation screen.
3. Station design to be simplified
The typical u-shaped structure can be completely separated from the station structure when passing through the station, which means, the main structure of the station is basically composed of the u-shaped structure itself. This will allow the structural slab to be consistent for the whole line.
Other structures of the station, such as roof, ticketing hall, equipment room, etc., can be built independently of the main structure.
4. Flexible and convenient construction
According to the actual situation of the project site, the construction of the U-shaped structure can adopt different construction methods such as full span prefabrication, segment prefabrication, on-site assembly or on-site casting etc. In addition, the construction of U-shaped structure has the advantages including short construction period, little impact on ground traffic during construction, and flexible construction site.
5. Project cost to be reduced
As the height of the structure is reduced, so does the height of the station，that can obviously reduce the cost of the project (for example: cancellation of the cost of escalators, etc.). In addition, the cost of concrete slab is reduced compared with traditional box beams. Generally, the total project volume and investment cost can be saved more than 20%.
6. Easy to set up the safety evacuation walkway
The safety evacuation walkway can be provided on the upper part of the web of U-shaped structure, which is at the same level of the train floor, so as to facilitate the evacuation of passengers in case of emergency. This is a specific design of U-shaped structure for safety reasons. This is the most significant advantage and characteristic compared with the traditional elevated structure.
7. Derailment prevention device
Normally, on the viaduct, anti-derailment devices must be installed to ensure safety. Conventional structures usually require the use of concrete derailment walls or guardrails. For the U-shaped structure, since the train is located between the webs of the structure, no additional derailment prevention devices are needed.
8. Centralized arrangement of equipment
The equipment for signaling and communication as well as the cables can be installed on the web of the U-shaped structure, which can help reducing the space occupation and facilitating the operation and maintenance of equipment.
Based on these advantages, the U-shaped structure is considered as an advanced design, which will play an important role for the development of urban rail transit.