Cycling in Melbourne Australia
Snap Send Solve
Both Snap Send Solve and NeatStreets act as clearing houses for reports on reports on just about anything, they forward the report to VicRoads, the local council, Vic railtrack or whoever else they believe is responsible for the issue that you report. I'm sure there are other similar apps or website, and using them sure beats having to figure out for yourself who to try and report things to.
It is entirely up to the receiving body whether they actually do anything about the report and how long they take. The good thing about them is that you've got a record of the report and you can keep banging away at it until something gets done, bad point of both of them is that I've found they have the 21st century attitude that being aware of a problem is equivalent to having fixed it, several times I've reported things, NeatStreets passes it to the council, the council replies with "thank you for your report, we have passed it to an officer for action", NeatStreets promptly closes the issues, months later nothing is done.
For example; http://www.neatstreets.com.au/Report/10004763 is a sign on the bike path at Huntingdale station, the council removed the ruins of the old sign two weeks after it was reported, but a further three weeks on and they've done nothing about replacing it, quite happy to tell NeatStreets that "The work has been completed".