Hi at all
i see this video http://www.youtube.com/watch?v=o4MqKPSYl6Q&feature=related
and it's a easy way to find the pap without a armadillo but i have a question:
on the step 4 of the video the person draw two lines perpendicular to the track and the intersection of these lines is the pap.
My question is:is there a measure (an exact point on the track) where to start to draw  the first line ?
The second line is drawn from the track through the midline of the span.
Any help is appreciated.
Thanks in advance