I have written a perl script which can fix a "braided" street in US TIGER data, as described at

osm.wiki/index.php/TIGER_fixup

It is a command-line tool which will download and fix the ways, and produce a file which you can open in JOSM to verify and upload.

You can find it at

http://svn.openstreetmap.org/applications/utils/filter/osm-unbraid/osm-unbraid.pl

Please give it a try and let me know how it works out.