RCP Tracks has a link to a "Track Builder" on its website.
http://www.rcptracks.com/html/home.html
http://www.trackbuilder.com

Although it is geared more toward onroad, one is still able to configure the tracks and save the file. RCP Tracks is also supposed to be adding new sections and tile types to its tracks, so eventually it will probably upgrade the track builder program. There was also another program which was available for download though I no longer have a link to it.

Off course, Roar Racing has specifics on lane widths, barriers and so on in the Roar Rules which can be used with the RCP Track Builder program for specifics once the layout is designed.
http://www.roarracing.com/rules.php