I've used
Corel Draw to design a track.
If you know how to use Corel, it's simple. You just measure your track area, create a page size with the same proportions, and scale a pen to your lane width. In my case they are 8 ft wide. Then freehand draw your track.
(the black border around the outside of the track in this drawing is the actual usable track area)
If you don't want to pay for something like Corel, you can always download
'Inkscape'. It's a free vector drawing program.