My town (Groton MA, USA) has 110 miles of trails open to the public, but virtually no signs helping people navigate at intersections in the woods. I am on the Trails Committee, and I'm pushing hard to address this.
Initially I figured we'd just do whatever other organizations do that have been at this for a long time. Just about all backwoods trail signs I've ever seen have been simple routed wood. It seems the US forest service has been using this type of sign for many decades, perhaps a century. For example:
This happens to be from the Tonto National Forest in AZ. It's about as typical a trail sign as there is in the US.
This one is on the top of Mt Lafayette in the White Mountain National Forest of NH. Again, it's basically the same design. The sign at top was recently replaced, and I'm not sure if it is more yellow due to being newer and not weathered yet (this location is above treeline open to the sky all year), or whether it's the new "composite" material that is plastic and wood.
Presumably the Forest Service has looked into this and converged on something that works and has low lifetime cost. If it's good enough for the US Forest Service, it's good enough for me.
However, we have had several people pushing us to use newer plastic material that is claimed to last longer than wood, although its also much more expensive. The main body of the plastic is white, but the front has a layer of dark green on it. Routing lines into it cuts thru the front layer to expose the back, so you get white letters on dark green. I've seen these signs and they are quite readable.
The question is, do you know of any experience with different materials for trail signs? Are most wood because that's all that's been available until now? Are there organizations that are using newer materials where they would have used wood signs in the past? If so, is there any longevity data, lifetime cost data, etc?
Also, any opinions on the esthetics? If you were hiking the back woods of a small town in New England and came accross non-traditional trail signs, would you think Yuk, this high-tech stuff doesn't belong in the woods, or Cool, these guys are keeping up with the times, or something else?
Added about plastic signs
I didn't have a picture of the type of plastic sign I described, so I took one yesterday afternoon:
This sign is by the side of a road, so is larger than what would be in the woods. However, this is the material I was mentioning. Apparently it is also available in brown. I have been told that this material will last much longer than wood, and is supposed to be able to stand up to long term UV exposure.
I have meanwhile heard back from one sign maker with some good arguments against pressure treated wood. That and Karen's point about not knowing what volunteer resources might be available in the future to replace worn signs has me leaning towards a format like the wood signs shown above, but using the plastic material shown here.