Hello fellows, I need to cut (split) a polygon in many parts. Any idea how colud I do it in ModelBuilder ? or other way.

[FlavioFelix]

[DarrenWiens2]

Can you describe exactly what you want to happen, so simply that a computer could understand? For example, what do you want to happen in the curvy part of the top triangle? If you can't describe it in terms of extremely simple rules, you won't be able to automate it.

[FlavioFelix]

I really have no idea how to start to automate it. But basically is to automate the split of the roads. Nowadays I do it line by line and then cut the polygons.

[DanPatterson_Retired]

split line at point (requires points first) and 

split line at vertices (won't work in all your cases)

I suspect that this may be one of those jobs that you will spend more time looking for a perfect automated system than it would take to do the job manually with the ability to make those nanosecond decisions as to where to split... ie around your curves.  

[DarrenWiens2]

I think this can be done by identifying "critical" points (i.e. those that surpass some threshold of angle [e.g. <45 degrees at points 10m away, or something]) and then extending a short cutting line opposite the angle. Of course, this will take you some time to figure out the math, learn Python, script, deal with unforeseen errors, etc. In the end, depending on how many times you need to do this (are we talking tens or millions?), as Dan_Patterson‌ says, it may not be worth figuring out.