f1_board_a.tga.dds for "do-it-yourself" track updates.
This file goes into the patchup_ot_pssg_textures folder created by Ryder's PSSG Editor, after Export All Files is clicked while the relevant patchup_ot.pssg file from most f12013\tracks\circuits\(folder) is opened into it. Once that file is copied into that patchup_ot_pssg_textures folder, clicking Import All Files and then selecting File | Save from the menu will give the above result (as seen at the pit exit in Melbourne here).
Since this mod is now updated with a different file, the previous "black 'n blue" one that is also visible above the white board (that previous file goes in the route_0\patchup_ot2.pssg file) is still available for download at the Version History tab near the top of this page: click on the download link on the right side of the 2014-03-15 line.
As always, back up all your files b4 making any mod.
Both files can be used by all modders without needing to ask permission 2 use them.
They're both "Open" files, so 2 speak.