Miami-Dade leaders have been talking about a massive expansion of transit systems in the county for more than 15 years, but little has been done. There's the pressing issue of how to pay for these things, compounded by constant infighting over which project should be pursued first.

Yesterday the county's Metropolitan Planning Organization, a central planning board made up of both elected officials from county and various city governments, agreed to pursue the "SMART" plan (AKA the Strategic Miami Area Rapid Transit plan). The ambitious idea calls for the construction of six new rail lines throughout the county.

Here are the lines included in the plan:

The "Beach Corridor" (formerly known as Baylink): The rail would connect Miami Beach to the mainland via a light-rail system along the MacArthur Causeway, but on the ground, the line would extend up through South Beach on the beach side and up into the Design District and midtown on the mainland side.

Tri-Rail Coastal Link: Already well under discussion, the plan would involve a second Tri-Rail line that would connect the downtowns of Miami, Fort Lauderdale, and West Palm Beach.

South Dade Transit Way: This plan would convert the existing enhanced bus service lanes along southern U.S. 1 into a light-rail transit system.

The East-West Corridor Along the Dolphin Expressway: The rail system would connect downtown Miami to the western suburbs and would run roughly parallel to the perpetually clogged Dolphin Expressway. Previous discussions had involved constructing the system on existing but currently privately owned tracks.

The North Corridor: This system would start at NW 79th Street and run along 27th Avenue.

The Kendall Corridor: The line would begin at Dadeland Station and run west along Kendall Drive.

Essentially, all of these lines would help fill in the gaps not covered by the existing Metrorail line, but because Metrorail tracks and stations are costly to build, most of the systems would be less costly light-rail tracks.

The plan also commits to expanding rapid bus transit systems in Miami.

Of course, none of these ideas are particularly new. Some date back decades, but the adoption of the plan kicks all of the projects up to "top-priority" status. Studies on how to pay for the system will begin immediately. According to the Miami Herald, that could include pitching voters on raising sales taxes once again. The county may also ask local city governments along the rail lines to pitch in.