2) Each trail should have an identifiable name and every intersection should have a sign with the names in both directions--just like street signs.
3) Discontinuous trails (like the extraordinarily confusing "Four Mile Run Trail") should be broken into parts with each part given a distinct name to avoid confusion. Trails should also only have one name (problem; there are parts of the W&OD that are also the Four Mile Run Trail and parts that are also the Custis Trail; a part of 4-Mile Run is also called Barcroft Trail. . .and I even saw a sign the other day that said "Anderson Bikeway," along 4-Mile Run, whatever that is).
4) Signage needs to be maintained and updated as changes and improvements are made.
Think of how much information drivers have. Each exit has a number, describes locations accessible by it, tells you what road your on (and which mile you're at) and where it goes, and where the next exit will take you. There are signs letting you know which jurisdiction you're in, laws etc...It isn't quite the same for cyclists. There are 'exits' off the W&OD that have no signs. Where do they go? Who knows.
Speaking of which, I just noticed that last year Toole Design worked on a Bethesda Trolley Trail Wayside and Information Initiative. Admittedly, this deals with much more than just signage - the waysides include several elements such as art, parking and seating. But it adds plenty of map kiosks. Phase I of the plan would include up to 17 map panels, with more to follow.
Photo by M.V.Jantzen