Members of a House transportation subcommittee began "preliminary" discussions yesterday of an ominibus measure to relax government regulation of the nation's railroads with the intention of marking up the bill possibly as soon as next Tuesday.

In opening yesterday's session of the Commerce Committee's subcommittee on transportation and commerce, its chairman, Rep. James J. Florio (D-N.J.), called the measure "essential to the economic well-being of all parts of our economy." He noted that the bill was a high priority of the administration and his subcommittee as well.

Like a measure that passed the Senate earlier this month, the House bill, introduced by Florio and Rep. Edward R. Madigan (R-Ill.), would make substantial changes in the way the nation's freight railroads are regulated.

The meausre would give the railroads more flexibility to raise and lower rates independently of the Interstate Commerce Commission, reduce the use of rate bureaus that allow the railroads to get together and agree to set rates, and outline a national rail policy that emphasized competition to the maximum extent possible and minimizes the need for federal regulatory control.

While there is progress in the House on the railroad issue, there has been no word yet on another administration priority -- the trucking deregulation measure that passed the Senate early last week.

Staffers for Rep. James J. Howard (D-N.J.), chairman of the surface transportation subcommittee, said last week the panel would begin marking up the bill the week of April 28 so that a measure might make it to the president's desk by a June 1 target date. But nothing has been scheduled yet Howard, who is said to be the object of intense lobbying couldn't be reached for comment.