Business: Metrorail Fleet in Major Refurbishment
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"The general overhauls and repairs of the coaches were becoming increasingly costly for Prasa," says Oredus Mattheüs, Transnet's general manager for product development.
"After we had reviewed the condition of the fleet with Prasa, we conducted a feasibility study. The study looked at the options of continuing with the general overhaul process or replacing the bodies of both the trailer and motor coaches. It was decided that a complete upgrade utilising 3CR12 stainless steel was the most cost effective option. This is a far cheaper alternative to buying new rolling stock at approximately 15% of the price."
Passenger and driver safety
As part of the upgrade, the interiors are revamped and modernised to be vandal proof. The seats are made from materials that cannot be cut, the walls can be washed clean of graffiti, and the doors and windows have outside slider mechanisms. The seats now hang from the sides of the train to allow cleaning by a high-pressure hose.
Mattheüs spells out the primary new safety features:
* The doors cannot be opened while the train is moving;
* The windows only open half way; and
The end-doors allow passengers to move from one coach to another in the event of an emergency.
The design lifespan of the suburban coaches is typically 30 years. During this time there are usually two general overhaul interventions to repair rust, replace obsolete components and repaint.
"This," says Mattheüs "has become extraordinarily expensive. Transnet Rail Engineering's design for the upgraded 10M5 coaches means that the bodies of the coaches don't have to be touched for the entire 30 year lifespan. The savings will be huge."
The original coach design caused water to leak into the bodies, which caused the bodies and floors to rust. Now, sliding doors and a new method of fastening the panels on to the underframe will ensure minimal water ingress. This, as well as the use of stainless steel, will ensure corrosion is contained to a minimum.
Although the floors remain mild steel, the rest of the train's body work and components will be made out of 3CR12 grade stainless steel.
"3CR12 has corrosion resistance second to none," Mattheüs clarifies. "Based on our past experience of using it to build coal wagons, the decision was obvious."
All Transnet's jumbo coal wagons are completely 3CR12. South African coal is aggressively corrosive, and induces serious pitting corrosion if it comes into contact with mild steel. This would result in the bellies of the original wagons, which were made from Corten (EN50B), needing to be completely replaced within 10 years.
"Although 3CR12 is more expensive than mild steel, it is much cheaper than other stainless steel grades such as 304 or 309. It is markedly cheaper than mild steel over the lifespan of the wagons. In addition, it is more weldable than other stainless steels," says Sassda's Vic Fear.
Keeping it green
In accordance with the many laws and by-laws promulgated by government to encourage environmental sustainability, Transnet has a number of practices in place.
"In addition to using the only 100% green metal, stainless steel, we recycle scrap, sell it to scrap metal dealers or to steel mills for reuse," says Mattheüs.
Transnet Rail Engineering takes 35 working days to upgrade each unit. The process starts with the unit being stripped of the components that require refurbishing. Everything under the floor is taken off and sent to be refurbished, including vacuum cylinders, brake equipment, the entire bogey, wheels sets, springs and rubber components.
"Everything removed is refurbished, replaced or condition-assessed and then used again," says Mattheüs.
Once stripped, a step-by-step process starts:
The top of the body structure is cut off and becomes scrap metal;
* The underframe is prepared and rusted components and standard
portions are replaced. Rusted side-sills and floors are replaced
with redesigned units;
* Shot blasting, undercoating and auto-coating ready the under frame
for a new body;
* The body panels are produced at Transnet Rail Engineering in
Koedoespoort, Pretoria, and shipped to the other three factories
in Bloemfontein, Durban and Salt River in Cape Town. When they
arrive they get aluminium slag blasted, cleaned and given an
* The underframe is levelled out and holes are drilled for the
* The panels are joined to the underframe with friction fasteners;
* The roof is equipped with wiring and brackets for mounting components;
* The roof is joined to the structure (the modular design ensures
the panels are replaceable in the case of minor damage);
* A covering coat is painted inside the unit;
* Mechanical and electrical equipping then takes place;
* Underside components are refitted to the underframe;
* The couplers are put in;
* Windows and doors are fitted;
* Final painting is completed; and
* The completed units return for commission as part of a module
consisting of one motor coach and three trailer coaches.
Mattheüs emphasises that all the new cabs are built at Transnet Rail Engineering in Koedoespoort. The modules are ready for use when they arrive at the factory where they are required.
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