Rails lose their shape because of wheel impact, abrupt acceleration and braking as well as from extreme heat, vibration and movement. Removing irregularities from worn rails reduces noise which results in a smoother ride and extends the track life.
Two machines are used to grind the track the largest being ‘the mainline’ rail grinder which is 180 metres long, nine wagons and weighing approximately 650 tonnes. It looks a lot like a train but travels between eight and 12 kms an hour, grinding the rail as it travels.
A slightly smaller ‘turn out grinder’ is used to grind small sections of rail, such as crossings and rail deviations. This machine is 55 metres, five wagons and weighs 160 tonnes.
The grinders can only operate safely when there are no trains operating on the same line. To minimise inconvenience to the thousands of people who travel by train in Queensland each day, the necessary track closures are generally scheduled between the last evening service and the first morning service.
People living close to the rail corridor may hear the rail grinder for a few minutes late at night as it approaches and moves past their properties. In most cases the noise will last only a few minutes.