Transnet Freight Rail could need to spend R11 billion on a new Overvaal tunnel to raise the capacity on its coal line to Richards Bay.

Burtie Maree, a commercial manager on the coal line, said yesterday that the existing Overvaal tunnel, built in the 1970s, was "the biggest single bottleneck on the coal line".

The 1.4km tunnel limited carrying capacity to 86 million tons of coal a year.

Richards Bay Coal Terminal is spending R1.1 billion to expand its annual export capacity from 72 million tons to 91million tons by mid-2009.

A new tunnel would take the line's capacity to 128 million tons at a cost of R11 billion. - Justin Brown