It indicates the width of a trail or path depicted on the map, helping hikers or map readers understand the size and type of path they will encounter.

Here's how it might be used:

* "TW 20ft" means the trail is 20 feet wide.

* "TW Narrow" indicates a narrow trail, potentially difficult to navigate.

However, it's important to note that the meaning of "TW" can vary depending on the specific map's legend or key. Always refer to the map's accompanying documentation for the most accurate interpretation.