Roadwalking is a thru-hiking term, indicating a walk on a road instead of a trail. It usually provides an easier way to reach a farther point on the trail, e.g. by avoiding steep mountain ascents. A roadwalk is an unavoidable part of some long trail systems, such as the partially unfinished Continental Divide Trail.
Roadwalking is not to be confused with "yellow blazing", or traveling in a car instead of by foot.
References
Roadwalking Wikipedia(Text) CC BY-SA