Hi ! Both annexe 14 (8th edition) & DOC 9157 part 2 (5th edition) shows tables of minimum taxiway width function of OMGWS Outer main gear wheel span, I fly 737NG with a OMGWS above 6 m which gives us a minimum taxiway width (in straight line) of 15 m. I guess the A 320 has almost the same dimensions as the -800 , flight can be dispatched regarding the NOTAM unless your OM PART A says otherwise.