XTrkCad is a CAD program for designing model railroad layouts. XTrkCad supports any scale, has libraries of popular brands of turnouts and sectional track (plus you add your own easily), can automatically use spiral transition curves when joining track, and includes extensive on-line help, demonstrations, and examples. XTrkCad lets you manipulate track much like you would with actual flex-track to modify, and extend and join tracks and turnouts. Other features include tunnels and animated trains.