Calculate number of roads crossed

Jun 2014
Hi guys,

I have a really tricky problem here and I'm hoping that there is a math guru here who can help.

The problem

Using Google maps, I need to allow a user to draw a line. This line can be in any direction and basically, I need to determine if the user has drawn the line over a road and if so, how many.

Below is an example:
The image doesn't seem to be showing so here is the link: View image: map basic

With Google Directions service, I am able to get the nearest road the the dropped marker (markers indicated by arrow in image).

For a single road, I believe that I can do this with Pythagoras, but for multiple roads by brain starts to boil.

If anyone here could help, I'd really appreciate it. I appreciate it is pretty tough so I'm open to all suggestions.