Design Aspects

Tubular Track is designed to suit the site-specific requirements of clients in respect of axle loading, operational speeds and annual tonnages, and are optimised to suit prevailing geotechnical conditions.

The twin reinforced concrete beams and the layered formation on which they are laid, are designed as an integral system by the System Designers. The importance of this integral system cannot be over-emphasised, and Tubular Track must only be laid on formation constructed strictly in accordance with the system design.

The twin beams are tied together using specially designed galvanised steel tie bars, the ends of which encircle the beams and are thus not cast into the beams. This enables easy replacement of the tie bars, and also ensures that the tie bars do not work loose under repetitive dynamic forces.

Tie bars are spaced at 3m intervals on straight track, and at lesser intervals on curved track to accommodate lateral forces. Intermediate rail fastenings are provided on stirrups which also encircle the beams.

Rails are fixed to shoulders welded onto the tops of tie bars and intermediate straps by means of proprietary (Pandrol) fastenings.

Resilience is imparted to the system by means of continuous resilient pads (rubber bonded cork) placed under the rails. These pads are ideally suited for deflections, noise and vibration.

Transition zones at interfaces between Tubular Track and conventional ballasted track require special designs to accommodate the change in stiffness between the two systems.

Further research is currently being undertaken by the University of Pretoria in South Africa.

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