My sketchup model cannot create surfaces

SketchUp
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1

Hi,

I am architect and was working on a project site plan. The site plan I am trying to create has a lot of curved pathways. But somehow sketch up does not recognize them as surfaces even though I have checked of any small openings. there aren’t any openings. Still it does not make the pathway a separate surface.

Please help me.
I am uploading the screen shots of the model.
I use sketchup 2015 pro.

The image here above shows that the curved pathway highlighted even though is closed but does not create a separate surface.

Please help!!!

2

It would be much easier to help you sort it out if you upload the SKP file. Or copy the troublesome section to a new file and upload that.