than the other warp threads in this way drainage channels are formed wherein the upper fabric layer 50 has more drainage channels than the lower fabric layer 60 the drainage channels can also be formed by the thread structure of the warp threads 51 through 54 and 61 through 64 for this purpose the threads can have for example grooves in the longitudinal direction fig8 9 and 10 show a belt 3 comprising an upper fabric layer 70 and a lower fabric layer 80 the warp threads 71 to 74 of the upper fabric layers 70 and the warp threads 81 and 84 of the lower fabric layer 80 extend in accordance with the warp threads 51 to 54 and 61 to 64 in fig5 the upper fabric layer 70 and the lower fabric layer 80 are interwoven with one another by binding threads 46 and 47 wherein the binding threads 46 47 cross one weft thread 8 of the fabric layers 70 and 80 respectively fig9 shows a schematic plan view of the belt 3 the warp threads 71 to 74 are woven adjacent to one another adjacently arranged are the binding threads 46 and 47 the drainage channels 500 are formed by omitting every other warp thread set of the fabric layer 70 so that from top to bottom as.