Swedish mining giant LKAB is investing SKr1·1bn in three new trainsets and nine locos for the Malmbanan iron ore corridor. Heavier axleloads to boost rail capacity and cut transport costs form a key element in the company's strategy to boost production from 20 to 30 million tonnes a year

Dr Roger Lundén, Director, Charmec, Chalmers University of Technology

NOVEMBER 1998 is due to see the delivery of five prototype wagons with 30 tonne axleloads to the Swedish iron ore mining company LKAB. Developed by Transwerk of South Africa, they are the first concrete signs of an investment strategy to boost capacity and cut operating costs on the Arctic heavy haul corridor.

Competition in the world iron ore market means LKAB must make its transport chain more efficient. Projekt Malmtrafik was launched by LKAB, Swedish State Railways and Norwegian State Railways in 1993 with the aim of driving down costs to a level comparable with competitors in Australia, Brazil and Canada. This led to the creation in July 1996 of Malmtrafik i Kiruna AB (MTAB) and its Norwegian subsidiary MTAS to take over the rail transport operations. LKAB owns 51% of MTAB, with SJ and NSB each holding 24·5%.

Following visits to heavy-haul lines around the world, the conclusion was reached that the best approach was investment in higher axleloads, longer trains and more efficient terminals. A further investigation into 30 tonne axleloads on the Swedish Malmbanan and Norwegian Ofotbanen was undertaken by LKAB and the two rail infrastructure authorities Banverket and Jernbaneverket in 1996-97.

Luleå Technical University performed five investigations: three into concrete bridges, peat as a subgrade material and dynamic simulations for new wagons. US consultants Zeta-Tech undertook a parallel study on track maintenance and looked at the costs and benefits for infrastructure and rolling stock of moving from 25 to 30 tonne axleloads. Luleå-based consultants RCAB co-ordinated the studies with development of two prototype wagons to test track forces and running dynamics. One was fitted with a cross-braced version of the existing ride-control bogies, and the other with Amsted AR-1 bogies.

The studies found that the total cost for upgrading the infrastructure to take 30 tonne axleloads was lower than anticipated. Individual costs were lower for bridges and track, but higher for culverts and subgrade. Work has now started on the southern route (Malmberget - Luleå), and the northern route (Kiruna - Narvik) only awaits a decision by Jernbaneverket on upgrading the Norwegian section.

Optimisation approach

It soon became clear that iron ore transport on the Malmbanan had to be treated as a single coupled logistics system, requiring a total optimisation approach to lowering costs. This had to take into account the complexity and the flexibility required for operation of three production centres and two ports, the mix of ore products, passenger and freight transport, having several train operators on the same track, terminal restrictions and so on.

MTAB is only one of several carriers that operate on the line, although the dominant one. It does not own the infrastructure, but buys train paths and pays a fee per tonne-km to Banverket and Jernbaneverket.

The main conclusion of the studies was that an increase in the maximum axleload from 25 to 30 tonnes was possible and economically desirable. At the same time the top speed of loaded trains should also be raised from 50 to 60 km/h. The number of wagons per train should be increased from 52 to 68, raising the payload from 4160 to 6800 tonnes. Train lengths would be increased from 470m to 740m, which is the practical limit for the loading and unloading terminals. This would require lengthening of seven passing sidings on the northern line and three on the southern.

The mine terminals should be upgraded for continuous loading, reducing the terminal time from 5h to 90min. With unloading of the bottom-discharge hopper wagons at a speed of about 0·5 m/s, this would bring the round-trip cycle time down to 12h, allowing a reduction in the number of trainsets from 15 to 9. Vehicle maintenance will also be concentrated at one location (Kiruna).

This package offered a variety of cost savings: