The government on Friday said the Indian Railways' freight business is expected to rise between 9 to 15 percent during the next four years from the average growth of around four percent recorded during the last four years.The freight potential was revealed in a report on traffic optimisation which was presented to Railway Minister Suresh Prabhu here.According to the report, the railways will be able to meet its growth forecast if progress on completion of last-mile projects, doubling of traffic facility, signalling and electrification works is made at a fast pace. "The great leap forward would be achieved only with completion of dedicated freight corridor," the report said.The report observed that in the ensuing period various other capacity-augmentation measures will have to be completed such as improvements in the rolling stock, utilisation of alternate routes, higher wagon capacity and setting up of private freight terminals.