Great entry! Thanks for the photos. I’m sure I’ll come back to this one in the future when I need to map an underground structure.

Great writeup, thank you. I’ve been considering the process for contributing to the mountain bike trail mapping in Washington State. Thanks to your description I discovered I can use the Strava heatmaps as a potential source. I didn’t realize until now that JOSM already has Strava heatmaps built into their image layers. I notice the heatmap is very low resolution though which makes some tight switchbacks hard to define. Do you have any advice or tricks for finding a higher-resolution heatmap source or obtaining more detail from a non-Strava source?

Thanks!