Sorry, it's ugly and you have to do a hitTest with the blue lines in your mind

click the squares to rotate their vector
the button with 'res' returns ball to original position
the button with go! activates the vectorfield

Can you guide the ball till the end off the road without touching walls?
(It's possible, I checked)

Here you go:http://members.chello.nl/w.visser8/vectorfield.html