another alternative (easier to program, but not the "natural" representation) would be to put the data in a circle and use the same location for both arrival an

another alternative (easier to program, but not the "natural" representation) would be to put the data in a circle and use the same location for both arrival and departure. i did something similar for package dependencies - the code is offline now, but you can see a screenshot at http://acooke.org/portfolio/practicl/ http://acooke.org/portfolio/practicl/