In one instance, it was required that a section (approximately 1km of double line) of the Metrorail track had to be deviated to accommodate the new Gautrain line. The Client ultimately decided to use Tubular Modular Track for this deviation as it was the most practical solution to the numerous problems that were associated with deviating this section of track.

To begin with, the program for the deviation work was extremely tight and had to dovetail with the bigger Bombardier program which was already in place. Tubular Track was able to submit a suitable program that accelerated the work and met with predetermined mile stones. Secondly, access to the site was limited and by installing Tubular Modular Track (TMT), logistics was simplified by reducing material handling by up to 50% including the elimination of ballast and reducing formation widths. 

Furthermore, the complete deviation is in a cutting. This exacerbates the water problems that was and still is evident in the area. By using TMT, drainage is simplified and once the Gautrain line is complete, the integrated surface drainage, sub-surface and storm water drainage will guarantee designed drainage ensuring expected formation life.

This installation carries a warranty on workmanship as do all of our installations. This in turn offers the Clients piece of mind.

The opportunity to compare Tubular turnouts to conventional (ballasted) turnouts presented itself in this re-modelled yard as 4 Tubular turnouts were installed on the right hand stagger and the left hand stagger was equipped with conventional turnouts. As the turnouts would then be subjected to the same operating conditions and loads, one then can easily determine comparative performance by observing the rate of deterioration for each set. All the sets would be subject to 26 ton axle loads. Annual tonnages vary from 33 MGT to 133 MGT across the turnouts depending on their position in the staggers.

To date, turnout no D17 (insert) has carried in excess of 360 MGT. Maintenance to the turnout since installation has included over lap grinding on only one occasion and the replacement of the resilient pad, between the rail and beam, at 250 MGT.

The local track inspector indicated that the conventional sets required repairs on a three monthly basis while the Tubular sets have only required grinding on one occasion. 

Dr Hannes Grabe, from the University of Pretoria, carried out deflection measurements on both types of turn outs and his results indicated that rail deflections on the Tubular sets are in the order of 60% less than that of the conventional sets. This is very significant in the sense that in terms of fatigue life, a 40kg/m rail on Tubular beams will last longer than a 60kg/m rail on conventional track.

Conclusions after 3 years:

• If the maintenance cycle of the Tubular sets are at least twice as long as that of the conventional sets, then their service life should also be at least twice as long
• The Tubular sets are by far superior in handling longitudinal rail stresses
• The rail-wheel contact stresses are reduced on the Tubular sets
•  The Tubular sets are maintaining their overall geometry much better
• A 40kg/m rail can be used on Tubular Track for low volume heavy haul lines
• No tamping or screening is required for Tubular Track offering further savings

Turnouts at Transnet Freight Rail’s staging yard in Ermelo; With only housekeeping maintenance, these turnouts, on the heavy haul export line to Richards Bay, have seen 450 million gross tons of coal on the line.

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