Nevermind! In case anyone else was wondering, here it is:
http://ddot.dc.gov/service/sidewalk-repair
"A "new" sidewalk request requires a petition from a majority of the residents on your block and a public hearing."

My new question that I can't seem to find an answer for is, how does one go about creating a majority block petition?

Any ideas? Back story: I'm in DC. The small residential street I live on has a curve at one end, and just before the curve, the sidewalk disappears into some crazy weeds/shrubs/someone's yard. Wouldn't be a big deal, except I walk here every single day with a stroller, and it's a huge blind spot. I get worried that someone will be coming around the curve in a car and won't see us or we won't see them. For what it's worth, there is no sidewalk at all on the opposite side of the road.

Do I 311 this? It seems like a huge undertaking for just a 311 request. Do I have to petition and collect signatures of the neighbors?