by shaun on 07/04/08 at 1:48 pm
The Namibian Department of Transport and Consulting Engineers, Kleber & Associates , have displayed their faith in the Tubular Track Technology by specifying it for the first 25 km of the railway line reconstruction between Aus and Luderitz in southern Namibia.
This section comprises steep gradients and sharp curvature , while extreme temperature variations are also experienced in this portion of the Namib desert. The main contract was awarded to a fully-fledged Namibian Company, The Roads Contractor Company Limited, of Windhoek , Namibia .
The system comprises twin reinforced concrete beams, linked with steel gauge bars on which rails are continuously supported. As a ballastless system, it is then laid directly on a specially designed formation with a 50 to 80 mm grout layer under the beams to fine-tune vertical alignment. Pre-cast modular sections will be manufactured at Aus and the laying of the modules will be done by the technology patent holder, Tubular Track (Pty) Ltd, a South African company.
Resilience in the system is achieved by the use of rubber-bonded cork pads developed by British manufacturer Tiflex and placed continuously between the rails and beams. An interesting aspect of this rail link is the extensive sand dunes encountered as the line approaches the port of Luderitz. The ballastless nature of the Tubular Track system allows it to solve many of the normal problems associated with laying track on sand, as the fouling of ballast is no longer an issue.
The Tubular Track beam-track railway system, researched and developed in South Africa, has been viewed with scepticism by many conservatives . However, recent tests and results carried out by major rail authority, Spoornet, the national rail body in South Africa, should do much to allay these uncertainties.
Laboratory testing and approval of the system was done at the Spoornet Track Testing Centre in South Africa, while further in-track main line testing is currently being done between Rustenburg and Thabazimbi in north-west South Africa on a line carrying heavy iron ore and coal traffic. The system has also been in use for some years in coal-loading and other sidings, as well as at Metrorail passenger platforms with constant rail-to-platform heights.
Spoornet is respected world-wide for its narrow gauge (1065mm) railway expertise and for the research and development carried out at its Track Testing Centre.
The benefits of Tubular Track include the following:
- Lower maintenance costs
- Reduced rail stresses allow lighter rails to be used
- Vertical and horizontal track geometry remains virtually constant
- Ballast and tamping costs are eliminated
- No ballast fouling in sandy or bulk-loading environments
- No loss of track resilience due to ballast degradation
- Drainage problems can be easily identified and dealt with
- A narrower formation width is required, generating considerable savings on earthworks
Quote from Spoornet Report BBB5815 dated June 2004:
“The Tubular Track(r) modules were designed and tested in the laboratory for 22 ton/axle loading and 5 MGT’s per year for a design period of 20 years. The results of the laboratory tests and numerical analyses presented in this report, as well as two other reports that will be referenced herein, indicate that the Tubular Track system, as tested, is a well-engineered alternative to conventional ballast track in terms of its technical performance. “