and thus can be easily installed disassembled and modified in particular curved rails can be modified before installation so as to match various conditions at installation sites as a measure to facilitate the continuous assembly of running rails the joining block 13 is used to assemble the rails with 45 u00b0 inclined sections furthermore the invention also proposes a cutting and replacement structure by which a broken or damaged rail can be easily cut or removed from the rail track and a new rail can be easily installed in greater detail as shown in fig1 the damaged rail track can be repaired by following procedures of cutting a damaged rail portion 16 at an inclination of 45 u00b0 from a main rail m when the rail portion 16 is broken or damaged to the extent that rail function is lost preparing a repair rail portion 55 having a length matching that of the damaged track portion 16 and end sections corresponding to cut sections of the main rail m inserting repair joining blocks 31 into the main rail m through the cut sections and connecting the repair rail portion 55 to the main rail m inserting jigs into adjustment holes 33 in both side faces of the repair rail portion 55 see fig1 and aligning main assembly holes 32 of the repair joining blocks 31 with main assembly holes 51 of the main rail m and when the aligning has been accomplished fixing the repair joining blocks 31 to the main rail m by fixing bolts another aspect of the invention is that the height of pillars for.