OpenStreetMap
I moved to Maugansville, Maryland recently. So I probably won't do quite as much editing around the Alexandria, Virginia area. I've started lining up roads with the images for my new neighborhood, and I've started working on the nearby highway. If anyone can explain what I should do about relations for the highway, I could use a step-by-step guide.
Discussion
Comment from NE2 on 18 January 2010 at 05:19
If you want to add an existing relation, such as for I-81 in Pennsylvania, find it on http://wiki.openstreetmap.org/wiki/Interstate_Highways_Relations, get the number (183751), click the way, click the middle button on the right side above the plus, type the number into the text box and find that relation, and add it.
To create a new relation, select that option, and add the tags like the ones listed at the end of http://api.openstreetmap.org/api/0.6/relation/183751 . Then add it to the wiki page.
It's easier to use JOSM though. Once you have the ref tags added (through Potlatch if you prefer), download and open a file like http://www.informationfreeway.org/api/0.6/*%5bref=*%5d%5bbbox=-78,39,-77,40%5d (play with the bbox to get an appropriate size). If the relation appears in the relation box on the right, hit ctrl-F and find type:way ref="I-81" -child ref=81; if it doesn't appear on the right, you don't need the last part. If necessary, add the relation by clicking the 'j' link on the wiki page (make sure you have the remote plugin enabled). Then add the ways to the relation. If you need to create a relation, simply click an existing one and then hit the middle (copy) button, changing the route number.
The only disadvantage of using JOSM is that you can't add the direction as easily.