[closed] What is different about these intersections/off-ramps?

I am writing software that is trying to find off ramps along the highways. To do this I find ways with a highway value of motorway_link or secondary. I then go through all of the motorway_link ways and see if any of the nd ref="XXXX" are in common with the secondary ways.

This works pretty well, but it doesn't seem to work for all intersections/off-ramps. Here are two examples that don't work:

1. https://www.openstreetmap.org/#map=17/43.42071/-80.28191
2. https://www.openstreetmap.org/#map=17/43.44879/-80.17669

And here are two examples that do:

1. https://www.openstreetmap.org/#map=17/43.45355/-80.12442
2. https://www.openstreetmap.org/#map=17/43.49124/-79.98727

Can some one explain why the two I listed don't work? Any tricks or steps I need to add to my algorithm to make them work?

EDIT: Here is a HTML file (that uses google maps) that shows all the intersections that I detect: http://pastie.org/private/wnakelvwdkndpgeafwdg

As you can see my algorithm does well, but not not as well as i would like.