by Bernadine on 01/02/10 at 9:22 pm
In March 2007, 4 x 1:12 UIC60 Tubular Modular Turnouts were installed in the Transnet D-Yard at the Ermelo shunting yard. These turnouts were installed as part of the expansion and re-modelling of the facility.
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 staggerΓö¼├íwas 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.Γö¼├í
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.
- 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
- Γö¼├íThe 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