Nothing else has worked, so the Senate decided on something new yesterday to try to turn a profit at Conrail, the federally subsidized north-eastern railroad system.

The 90,000 employes who run the Consolidated Rail Corp., a hybrid of six failing lines that began business in 1976 would become part owners of the system under the Senate legislation.

The bill authorized the U.S. Railway Association to purchase an additional $1.2 billion of Conrail preferred stock to help meet its financial needs over the next five years.

But as a condition for going along with the new funding proposal from the Department of Transportation the Senate insisted that Conrail employes by given a piece of the action.

The bill authorizes the transfer of 15 percent of Conrail preferred - that is, stock worth $345 million - to the line's employes.

While history books will record that the Senate worked its will the Conrail stock-sharing idea belonged to Sen. Russell B. Long (D-La.) who for years has pushed employe-ownership plans.

When Long, chairman of the finance committee and bestower of senatorial favors has an idea his colleagues listen closely.

During the past five years four different bills coming out of Longs committee have contained tax-relief provisions for companies that establish employe-stock ownership plans - ESOP in the jargon.

The idea of course is a carrot and stick think. Companies that share the wealth with their employes are rewarded with some tax advantages.

Long stood outside the Senate chamber yesterday talking not unlike a man who had just discovered a better way to run a railroad.

"As long as the workers have no ownership interest," he said, "there is no practical incentive to make the railroad a big success."

"Give them a piece of the action and they will take an interest in seeing that Conrail makes money. it would be worth billions to them if they could move it out of the red into the black."

Long continued, "I think the eemployes can make the railroad succeed. Experience shows that where other ESOP's were set up, there was greater efficiency and production."

The commerce, science and transportation committee, which proposed yesterday's bill, noted efficiencies and speculated that employe stock ownership could help Conail turn the corner. The House has not yet acted on the measure.

But the Senate heard other evidence that the big line is a long way from reaching the corner. Conrail can't even cross the Hudson River at Poughkeepsie, N.Y. - and doesn't want to.

Conrail, on the grounds that it is not economical, has refused to rebuild the rail bridge that burned in 1974 at Poughkeepsie, a point advertised as the "gateway to New England."

So a freight shipment from say Washington to Poughkeepsie, would be rerouted 75 miles past Poughkeepsie on the west side of the Hudson to the next nearest bridge and then brought down the east bank to its destination.

Sen. Abraham A. Ribicoff (D-Conn.), insisted at length that was not a way to run a railroad and he won approval of a $9 million authorization to rebuild the span at Poughkeepsie.