Abstract: A slipform paving apparatus having a variable width frame assembly supported upon independently adjustable and steerable leg and track assemblies that are positionable in a paving profile or in a travelling profile. A detachable steering cable feedback and follower assembly interconnects a track assembly on one side to the respective track assembly on the other side, providing potential single side steering control. Road building implements include in sequence and in close proximity a traversing paddle assembly, a height adjustable vibrator assembly, a variable height strike-off assembly, a vibrated grout screed assembly, a profile pan assembly, and a float pan assembly cooperating with retractable slipforming means to form a finished concrete road lane upon a substrate. The implements are modularly designed so as to be capable of being parted and increased in road width building capability by the interdisposition of extension attachments between sections of each implement.