Rail and bus firm Go Ahead said it had seen growth slightly ahead of expectations in its bus and aviation operations over the first quarter and that rail operations were continuing to trade in line with forecasts.In bus operations, the company has seen passenger numbers lifted by concessionary fare schemes. Aviation services have benefited from an improvement in revenues from cargo handling, while its Meteor airport car parks performed as expected. Go Ahead's rail operations include the Southern and Southeastern franchises and the less well-known London Midland, which operates between the capital and the midlands and north west. 'We continue to assume that economic conditions will remain difficult, said the firm.