Consolidated Rail Corp. (Conrail) said yesterday it lost $54.7 million in the third quarter of the year and will probably need more federal aid than previously expected.

The loss, on revenues of $828.1 million, contrasts with a $32 million loss on revenues of $809 million in the quarter last year.

For the first nine months this year, the federally-sponsored rail system for the Northern and Midwest lost $289.9 billion.

The third quarter performance was "in line with the corporation's plans for the period," said Edward G. Jordon, Concrail's chairman and chief executive.

But frieght traffic for the quarter was 6.2 per cent below projections, Jordon said. Two rate increases in the past year were not enough to offset the loss of volume and higher costs, he said.

Much of the decrease in Conrail's freight volume was due to the troubled steel industry. Shipments of steel, ore, coal and metal products all were down.

Labor costs jumped $34 million and the cost of repairing rolling stock is running higher than expected, Jordon said.

The decline in traffic and need for extensive repairs of cars foul Conrail's plan for financial independence.

Jordon said the plan for the rail-road "foresaw only modest new equipment acquisition and the strengthening of Conrail's revenue bases as key, interrelated ingredients in the achievement of its ultimate goal."

"Our experience to date indicates that meeting to fleet requirements will result in greater financing needs than forecast."

A major marketing study of how to boost the system's freight traffic is underway, Jordon said.