Consolidated Rail Corp., the government-financed business designed to salvage the Northeast's railroads, reported a 1979 fourth-quarter loss yesterday of $48.5 million, bringing its total loss for the year to $178.2 million.

The unaudited results, Conrail said, indicate that the company was able to improve its fourth-quarter performance despite difficult economic conditions during that period, including an 11.3 percent cut in rail carloadings.

For 1978, Conrail lost $385.4 million and for the fourth quarter that year lost $60 million.

Edward Jordan, Conrail's chairman, said the "critical dimension" of the railroad's report is the fact that Conrail has been able to reduce its employment rolls and its expenses during the past year.

Jordan, in a telephone interview, said Conrail's work force was down almost 10,000 -- or more than 10 percent -- in the past two years.

Jordan said the railroad is "now equivalent to the average railroad in the country in delivering a level of service that is competitive." Therefore, Jordan said the company can "project a very favorable picture" for the coming year, especially if Congress passes sweeping railroad deregulation legislation, currently under consideration by House and Senate commerce committees.

Conrail officials have been arguing that the railroads would be far less dependent on government aid if they were free to set rates without the government regulatory apparatus.

Rep. James Florio (D-N.J.), chairman of a House Commerce transportation subcommittee, is planning to introduce today a revised version of railroad deregulation legislation, a bill that would eliminate most government monitoring of freight rates.

If deregulation legislation that gives Conrail the freedom it says it must have is passed by Congress, the rail line says it can survive on the $185 million allocated to it in the administration's budget message.

If deregulation is not enacted, Jordan said Conrail would need $553 million, under its contingency plans.

Jordan said the uncertain effects of a possible nationwide recession this year cloud Conrail's prospects. "There already is a recession in the North east," he said.

"What is holding our traffic up is the traffic from other railroads," Jordan said, "We're feeling the influence of the decline of the auto and steel industries in the Northeast."

Jordan said Conrail's ability to cut its fourth quarter and overall 1979 losses was based largely on general freight rate and fuel surcharge increases totaling 13.2 percent.

Conrail has benefited from the mild winter throughout the Northeast, and the company's early readings of the 1980 first quarter indicate a good period, he said.

Since it was formed almost four years ago, Conrail has used $2.655 billion in federal monies. About 89 percent of those funds have been used in physical asset improvement.