Setting the weld on fire

KiwiRail workers fuse rails together in a fiery display at St Leonards yesterday. This process minimises track wear and provides a much smoother, quieter ride. In the aluminothermic welding process, the rail ends are preheated, before iron oxide and aluminum powders are ignited in a crucible. 

The resulting molten iron flows into a mould and fuses the rail ends together. 

A KiwiRail spokesman said the workers were carrying out routine maintenance on the Port Chalmers to Dunedin line.