This .STL file will extend the width from 24” to 33.75”. The section is 9.75”, a common width for N-Scale Atlas and Peco track. It simply gets placed between the two end sections.
STL (Stereolithography, filesize: 821 KB), OBJ (OBJ, filesize: 1.26 MB), PDF (PDF, filesize: 555 KB), PLY (Ply, filesize: 1.05 MB)