South Carolina's oldest school buses - the worst of the worst - will be replaced with a $36 million appropriation in this year's state budget. Unfortunately, there's no guarantee that next year will continue the long-overdue process, And as numerous studies have emphasized, that's been a major difficulty in keeping a dependable bus fleet on the road.

To its credit, the House approved legislation that would establish a regular replacement cycle for school bus purchases, so that every 12 years the bus fleet would be totally replaced. The Senate Education Committee endorsed the proposal as well.

But Sen. Hugh Leatherman, chairman of the Senate Finance Committee, put the bill on the contested calendar, presumably for further review of its financial implications.

While the bill establishes a replacement cycle, the necessary funding would have to be provided each year legislatively. Nevertheless, it is a valuable recognition of a long-standing problem and affirms the Legislature's need to address it annually.

The replacement cycle should be approved by the Legislature when it reconvenes in January, committing the state to provide reliable transportation to school children, for example, now and in the future. Doing so would eliminate the necessity for South Carolina to, say, buy surplus buses from another state, as it did last year.

Moreover, it would reduce the high cost of maintaining an aged bus system that for the most part already should have been replaced. The decision to fund this year's partial replacement - incidentally, endorsed by Sen. Leatherman - recognized the immediate problem. The regular replacement cycle would resolve it for the long term, and should be finalized next year.