It's all money that Congress had appropriated for the last two fiscal years for Metro rail construction, but finally the Reagan administration has seen fit to let go of it. That's a relief for the participating state and local governments, not to mention those residents of Greater Washil,7p,85 ington who have been waiting the longest for their due share of rail service. When delays such as this affect construction schedules, the cost of the whole rail network goes up.

But freeing old appropriations is only one step. Congress is also moving to allow the second step, which is to continue reasonable financial participation by the federal government in this transportation partnership. With strong bipartisan support, the effort in Congress is to provide Metro with the same amount in fiscal 1987 as it is now about to receive from the fiscal 1986 appropriation that the administration was sitting on. This would be coupled with additional financing from the state and local governments, which have been releasing their shares willingly -- and on time.

While that is happening, Metro will continue its harder look at the full costs of completing the full rail system and also of operating and maintaining it. This should include a vigorous renewal of the search for dedicated sources of revenue, through a combination of taxes in the region. Otherwise, the state and local governments will have to be content with tax/revenue studies commissioned by the administration, which may or may not take into account the delicate points of local politics and finances.

In any event, the kind of commitment to financial reality that we outlined three months ago, when relationships between the partners were deteriorating, is now evident. There is agreement between Metro and the administration on the new steps toward completion of the 103-mile system and new promise of service in the near future for those who need it most. This is all the more incentive for Metro's federal/state/local partnership to go Metro's last miles.