It looks like it's back to the drawing board for the county's planners, who last week released a study indicating that the traffic generated by development outlined in the 30-year master plan for Columbia's downtown would overwhelm the local road network.

The plan has always been a work in progress, but it's clear now that something's got to give.

County officials say they are now looking at scaling back the amount of residential and commercial development in the plan. They also are considering a Columbia version of the Adequate Public Facilities Act, which restricts development elsewhere in the county when student enrollments and traffic counts exceed the capacity of schools and roads to handle them.

With Columbia essentially finished, it's probably time to impose some version of the ordinance regardless of the study.

One might even argue that the existing adequate-facilities law, which now excludes Columbia, ought to govern the whole of the county, that the New Town zoning unique to Columbia has outlived its usefulness.

The county was late in coming to the realization that an assessment of traffic capacity had to be in hand before plans for downtown redevelopment could be drawn with any confidence.

Better late than never.

Officials still have time to shift gears before the wheels of commerce go into motion.

We urge them to be more careful about their assumptions about what will and won't work downtown.