Construct a triangle with the angles A=90 B=59 C=31

Construct a triangle with the angles A=90 B=59 C=31:

'via Blog this'

This 31 degree slope would be the result of getting a 5.5 foot sidewalk encroachment in the 22 foot sidewalk. (90% of all sidewalks in SF are 17 feet wide, or less.)
It would be, then, equal to the two most well known  "Steepest Streets" in SF...: Filbert at Leavenworth and  22nd Street at  Vicksburg on Potrero Hill.

If the City refuses, the resultant  35 degee slope will be 13 % steeper, and too steep to be safe, and usable.
  The result:  the occupant's cars will be parked on the street,  negating the reason for having garages.

It is surprising that the SF DPW ignores these points and just says "NO.  We simply have a total policy of not approving  an encroachment, if it would be the first one on that side of the block, no matter how wide the sidewalk.  < Across from 253 Parker is 252 Parker which DOES have such an encroachment, but the DPW  ignores that, for no understandable reason.)