King County decided to replace the aging South Park Bridge with a low moveable span instead of a high fixed span, a decision endorsed by the Washington State Department of Transportation and the Federal Highway Administration.

The selection makes a lot of South Park residents happy because it spares much of the neighborhood's business district from demolition. Long approaches would've been necessary along 14th Avenue South for a high span, and many South Park businesses would have to make way.

Selection of a bascule bridge design not only spares 14th Avenue businesses, it sustains South Park's marine industry upstream from the bridge, said Tim McNeil of South Park. It also would improve freight mobility in the Duwamish corridor, he added.

It also clears the way for design to begin. About a third of the overall design will be completed during the next three months, including the footprint of the new bridge and how nearby intersections will lead to and from the new bridge, said Tim Lane, project manager.

Engineers studied five different options for replacing the bridge. Before picking the bascule bridge alternative, the King County Department of Transportation looked into rehabilitating the existing South Park Bridge, replacing it with 65-foot or 100-foot-high fixed spans, or tearing down and not replacing the bridge. A bascule bridge was the most expensive of the five alternatives studied.

The bascule bridge is planned to be built about 80 feet downstream from the existing bridge, Lane said.

The new span will be wider too. The existing bridge is 52 feet wide, but the lanes are just 9 feet, 6 inches wide

The new bridge is planned to be 64 feet wide. There will still be four lanes but they'll be 11 feet wide, with a median between.

The existing bridge has narrow sidewalks on each side. The new span would have one 13-foot-wide pathway on the downstream side of the bridge. It would be wide enough for bicyclists as well as pedestrians.

The draft environmental impact statement for replacement of the South Park Bridge was released to the public last fall. The final version of the document is scheduled for completion in spring 2007.

Tim St. Clair can be reached at tstclair@robinsonnews.com or 932.0300.