existing surface grade filtering slopes? Any ideas?

I am trying to find existing slope conditions along a 280 mile corridor. I need locations where a 5% and 3% slope exist within 100ft of the track CL (rail). Is there anyway that I can set up some type of filter that will highlight the area where these slopes exist?

I have rail track suite which also has inroads. I was looking at the surfaces and also the drainage tabs. I didn't know if it had something to do this.

-Tom