IT TURNED OUT to be the ugliest floor debate in the Virginia state senate this session, but the outcome was as decisive as it was important for the entire state. By a vote of 29 to 11, the senators agreed to a sweeping proposal that will allocate millions in highway money to Northern Virginia and other urban areas that desperately need road improvements. Among other good things -- for the roads and for the record of the legislature as a whole -- there is the likelihood now that many long- sought projects may soon bring relief along the heavily traveled secondary roads of this region.

Given the past history of rural domination in the Virginia legislature, the success of this measure came as a jolt to its opponents. But rather than read too much into whose bloc has the upper hand nowadays, those who screamed highway robbery -- and who are now vowing to play hell with allocations for Metro rail money next year -- should consider the big transportation picture in their state. That, in fact, is what many of the legislators who supported this proposal did; they also recognized that it was a fair compromise that did provide money and flexibility for rural road construction and repair.

One opponent, Sen. William E. Fears of Accomack, claimed that the highway formula will unconstitutionally discriminate against rural Virginians, and talked about filing suit to overturn the measure if it becomes law. Maybe he might consider insisting that highway money be allocated to each district according to how much money it raises in taxes for the state. That would be the logical follow-up to his ill-considered threat.

Another opponent, Sen. Madison E. Marye from southwestern Virginia, was one legislator who concluded that some sort of revenge is in order -- and says Metro will be a target. He managed to paint an interesting portrait of urban mass transportation, observing that "giving money to Metro is like pouring soap suds down a rat hole." Let's think on that for at least a year.