By William Crum Staff Writer wcrum@oklahoman.comThe MAPS 3 Citizens Advisory Board is to vote Thursday on plans to buy a sixth streetcar, which will be needed when service begins in about two years on the downtown tram line. Route revisions approved in February to serve the new location of the MAPS 3 convention center required that the city bump its initial streetcar order from five vehicles to six. The additional streetcar will cost just under $4 million, bringing the total for six vehicles to $28.9 million. The city council previously authorized the revised route and purchase of the first five streetcars, and is expected to give final approval to buy the sixth on Tuesday. The council is drawing $3 million from the MAPS 3 reserve fund to alter the downtown route, providing service enhancements that weren't possible with the original design. The revisions preserve the 4.6-mile mainline loop — now being called the "blue line" — through the central business district. A new "red line" loop will offer frequent service between the convention center, to be built south of Chesapeake Arena, and Bricktown. The revisions are expected to support residential and commercial development in the now-blighted district west of the MAPS 3 downtown park, which will share a stop with the convention center. The manufacturer, Brookville Equipment Corp.Read more on NewsOK.com