The extra width is for parking.  See this streetview image; the storm drain is at the end of the block (where a person is standing behind a pole in a red jacket).  <a href="https:&#x2F;&#x2F;www.google.com&#x2F;maps&#x2F;@37.3859607,-122.084495,3a,75y,128.94h,78.75t&#x2F;data=!3m6!1e1!3m4!1s7BQDxJuoN0LTimG8MDUonQ!2e0!7i13312!8i6656" rel="nofollow">https:&#x2F;&#x2F;www.google.com&#x2F;maps&#x2F;@37.3859607,-122.084495,3a,75y,1...</a>