It is sobering to think how impossible it is to evaluate the safety of a snow bridge. Since they melt out from bottom up, there is sometimes NO way to judge. There could be 3-4 feet of snow supporting the bridge, or just a foot--not enough to support much of anything.
Randy Morgensen, an experienced backcountry ranger died. Now here, a Sierra Club hike leader was fortunate to be rescued. With just a couple of different twists, the outcome could have been disastrous! Bob R's experience could have, too!
Here are some ideas:
- Check how close you are to where the stream exits (or goes underneath) the snow. Closer to the that point, the thinner it would be. But due to unseen undulations in the terrain, there could be thin spots far from the point.
- Maybe it would be possible to use a hiking pole to probe the snow to determine how thick it is.
- When hiking alone, best policy would be to avoid them completely. Of course that may be impossible to do.
Thinking back, I once tried to collapse a snow bridge over a small stream. This was a small stream, so no danger to me. I thought by stomping near the edge I could get it to collapse without my going in, and it would leave the crossing open so other hikers could see and cross more safely. Unfortunately I went in with the snow, and ended up with a wet boot.
