It was inevitable that, someday, the Senate would pass an important piece of transportation legislation and people would suggest that Majority Leader Robert J. Dole (R-Kan.) was taking care of things for his wife, Transportation Secretary Elizabeth Hanford Dole.

Last week, her plan to sell the federal government's freight railroad, Conrail, to Norfolk Southern Corp., a huge railroad holding company, became the case in point. The Senate passed the legislation, 54 to 39, and some of the sale's opponents were less than shy in suggesting impropriety.

Few were as open as Sen. Donald W. Riegle Jr. (D-Mich.), who said during debate, "I got the feeling . . . on this matter that, in a sense, the fix is in. It has been for a long time . . . . "

He went on to say that some senators he had talked to "do not have a good taste in their mouths about this. They might not say it the way I am saying it because of the relationships involved . . . . I think that sometimes we end up concerning ourselves on matters such as this, and we end up doing the wrong thing for our own personal purposes."

Riegle spoke shortly after the Senate had voted 70 to 27 to limit debate. Such cloture requires 60 votes for passage. Several senators who intended to vote against Norfolk Southern and the Reagan administration on final passage were more than willing to end debate.

Sen. John H. Chafee (R-R.I.), responding to Riegle, said, "I do not think there is any conspiracy in this body, as suggested, or that we are all lacking courage. What a suggestion, that in a vote of 70 to 27, 70 people here who voted that way somehow did not have the courage to stand up . . . . Clearly somehow the suggestion is that the secretary of transportation has a grip on us and that we do not know how to vote."

At which point Sen. Ernest F. Hollings (D-S.C.) injected a bit of levity, saying, "I wish she did."

The Senate did not exactly rush to judgment on Conrail. Secretary Dole selected Norfolk Southern from among 15 bidders on Feb. 8, 1985, and the first Senate Commerce Committee hearing on that selection was held last Feb. 27.

The Philadelphia Inquirer, in Conrail's headquarters city, said in an editorial after the vote, "Considering that President Reagan made an 11th-hour effort to drum up support with a letter to the transportation secretary endorsing her recommendation and considering also that Mrs. Dole's husband is Senate majority leader, the margin was hardly overwhelming."

Conrail's management and its employe groups have opposed the Norfolk Southern acquisition, preferring to leave Conrail an independent entity.

The suggestion of conflict is not new for the Doles, sometimes referred to in political circles as the Power Couple, or the Bob and Elizabeth Show.

In the early years of the Reagan administration, Elizabeth Dole was Reagan's assistant for public liaison and Sen. Dole was chairman of the Finance Committee during passage of tax bills in 1981 and 1982. White House officials were reluctant then to include Elizabeth Dole in strategy sessions on how to deal with the Senate, and when the Transportation Department position opened up in 1983, they were happy to move her to an important job well removed from the inner circle.

Both Doles have been mentioned as possible candidates for president and both are sought-after political speakers. They often take those opportunities to joke about their roles, but behind their quips is an obvious concern that one or both of them might be damaged by a perception of impropriety.

Secretary Dole has said on several occasions, "There are some things we just don't talk about." Sen. Dole, in a 1984 interview, said the conflict question "is a legitimate" one. "We just don't discuss a lot of that. She'll take some work home with her and get tied up on it; if you get home at 8 o'clock, 8:30, the last thing I want to do is get right into business. Get that Lean Cuisine out and eat it."

The Doles' concerns are transmitted to the staffs in both the Senate and the Transportation Department.

"Had I been the secretary of transportation, I would have leaned all over the majority leader to move that [Conrail] bill, and she just didn't feel that was appropriate," a department source said.

Another department source said, before the Senate debate began, "When he was named majority leader, we thought it would be a great help. It turned out to be a hindrance. We just can't do some of the things we would normally do on legislation we wanted."

And Secretary Dole conceded some frustration about problems the appearance of conflict is causing for her legislative program. In a conversation about the Conrail issue prior to Senate action, she expressed frustration over the pace of the legislation. "I said to Bob the other evening, 'Do you have to bend over backwards so far that I can't even get one bill on the floor?' " she said.

In the Senate, one staffer pushing the administration legislation expressed similar frustration. "The leadership is being very careful on this one, which is one reason we couldn't get the bill through before the Christmas recess," the staffer said.

Another said, "They say they don't talk to each other and they really don't. There have been several times when we just assumed something we had discussed with the senator was known by the department, and it turned out not to be."

Sen. John C. Danforth (R-Mo.), chairman of the Commerce Committee, handled the Conrail legislation on the floor with little visible help from Sen. Dole, who was absent for most of the debate.

As the debate drew to a conclusion, a number of senators praised Secretary Dole's role. The most active opponent of the legislation, Sen. Howard M. Metzenbaum (D-Ohio), said, "I want to publicly say the leader of the Senate has been fair. And I don't think any Cabinet member with whom I have worked has ever been more gracious or willing to work."

Sen. Dole himself, who has a marvelous ability to deflect almost every hard question with a quip, said, "I too would commend the secretary of transportation, because I want to go home tonight."