INTRO: Faced with an ageing and increasingly unreliable motive power fleet, South Africa’s national railway has launched a major programme of upgrading and renewal. Bids are being called for new high-tech locomotives which will give Spoornet the ability to overcome a legacy of different electrification systems
BYLINE: Leo Petkoon and Dr Chris J Dutton*
OVER THE next 15 years, Spoornet expects to invest R15bn in a wide-ranging upgrade and modernisation of the South African rail network and its main line locomotive fleet. Three contracts have now been awarded for the mid-life overhaul and re-engineering of electric locos used on heavy-haul services, and the first refurbished Class 9E is due to roll out in October.
Bids were to be called last month for a fleet of up to 600 dual-system locos designated All-Purpose Traction (APT) using modern technology. To be ordered early next year for delivery from 2004, these will gradually replace an eclectic mix of designs, allowing the best of the existing fleet to be upgraded and cascaded onto different routes. Improved availability and higher performance will allow Spoornet to halve the size of fleet, with significant cost and productivity benefits.
Spoornet’s existing fleet of 1932 electric and 1200 diesel locos has an average age of 25 years. There are nine different models of electric loco and six diesels from seven different suppliers. More significantly, there are 12 electric and 14 diesel technologies with 2488 locos having outdated traction equipment more than 20 years old. A further 631 use technology between 7 and 15 years old, and only 63 locos have traction equipment from the last five years.
Average class availability ranges from 75 to 85%, with electric locos recording 46 faults per million km and the diesels 55. This is reflected in the utilisation figures, with electric locos achieving an average of 8409 km per month and the diesels only 3973 km.
The wide variety of suppliers, models and technologies means that Spoornet needs to stock a wide range of spare parts, which has cost implications in terms of working capital. In addition, maintenance and operating staff need a wider range of expertise, and additional facilities are required to cope with the diversity. There are also significant differences in design philosophy between suppliers.
Spoornet has three electrification systems as well as many diesel-worked routes. Whilst the 50 kV AC iron ore line between Sishen and Saldanha is relatively self-contained, other corridors can have a mix of 25 kV AC, 3 kV DC or no electrification at all (Table I). This complicates the specification and use of motive power.
A further complication, although not as great, is the axleload limitations on some parts of the network. We are now able to handle axleloads of 22 tonnes for general freight traffic on most main lines, and are working on the assumption that this will be available throughout the electrified network in future.
All this adds up to give a poor overall performance, with availability and reliability significantly lower than would be possible with a more standardised fleet using the latest traction technology.
In considering renewal strategies, we have evaluated the concept of an APT locomotive against traditional line- and/or application-specific designs.
Table II shows how the major classes are currently deployed on different traffic flows, in many cases requiring multi-loco formations. As part of the re-engineering process, there will be opportunities to ’cascade’ mixed traffic designs from one flow to another, working towards a simplified fleet more closely aligned with business requirements.
In looking to set its future traction strategy, Spoornet adopted a number of guiding principles. These included: