Long before South Iowa Street became the traffic-clogged, big-box-lined corridor it is today, there was one store, Kmart, and little idea about what would follow it.

Officials hope the next “regional commercial center”  probably at Sixth Street and the South Lawrence Trafficway  is planned more carefully. Proposed revisions to Horizon 2020, the city-county planning guide, would require developers and planners to plot out an entire corridor before the first shovel of earth is turned for the first store.

“It developed piecemeal,” Linda Finger, the city’s planning director, said of South Iowa Street. “You had plans for the individual developments, but not for the entire corridor.”

The proposed revisions, she said, are “the difference of the community planning for change and the developer planning for change.”

Discussion of possible revisions came Wednesday morning during a Lawrence-Douglas County Planning Commission meeting. Planners noted that Horizon 2020 says little about regional commercial centers, except to say one is not expected soon.

Officials think that is no longer the case.

The revised plan would require developers to pay for a market study by an independent consultant, agreed upon by both the city and the developer, who would examine the viability of the proposal and how it would affect other commercial areas in town.

The study also would create a phasing plan to map out when construction could occur on individual developments within the corridor.

“The big questions will be where and when,” Planning Commissioner Myles Schachter said.

Horizon 2020 is also silent on the location of regional centers. The subcommittee revisions suggest they be located at the intersection of two state or federal highways, or at the intersection of a highway and major “arterial” street. That leaves Sixth Street and the SLT as the most likely spot, though that hasn’t been spelled out in the revisions.

Tim Holverson, vice president of public policy for the Lawrence Chamber of Commerce, said developers would probably welcome a more orderly process for planning regional centers. It might put an end to divisive arguments that arise every time a big-box store wants to come to town, he said.

“Overall that sounds like a good idea, the way we should’ve done it in the first place,” he said. “It’ll make for a lot less contentious meetings. But I think it’s important that all the interested parties are at the table during the planning process.”

Officials said a final proposal for the revised commercial chapter might be considered by the planning commission in October.