Audible fences should not be barriers

Investigating a routing issue I discovered that the node in question (431495501) was described thus:
barrier=fence
sensory=audio (I have also seen sensory=audible)

In Australia we have audible fences that are used to prevent livestock (and wild dogs etc) from passing the barrier. These fences do not stop traffic (and are not meant to) as there is no physical fence.
I question if these should be declared as barriers.
The alternative would be to add the access=yes but that looks wrong to me.
This is an example - the route along the Balonne Highway.
https://map.project-osrm.org/?z=10&center=-27.957411%2C147.402191&loc=-27.965088%2C148.163815&loc=-27.993189%2C146.766357&hl=en&alt=0&srv=0
OpenStreetMap Routing with Open Source Routing Machine

openroute service does not suffer from this issue. However I still question the use of barrier in this case.
(https://maps.openrouteservice.org)

Node 8713921290
barrier=fence
sensory=audible

I agree this tagging is questionable and should almost certainly be changed.

The key “sensory=” is used only about 100 times in the whole world. Outside Australia, it is used mainly on playgrounds (for which it is documented), or on other features where it conveys a similar concept (i.e. that the feature is designed to provide a certain kind of sensory experience for humans). (overpass query)

In Australia, in contrast, it is used in quite a few places similarly to this node. Clearly a deterrent for animals is a very different concept from a sensory experience for humans.

Given the low usage and the fact that its usage on barriers seems to be undocumented, no router is likely to use this secondary tag to “understand” the barrier. So the impact on routing will be dependent on the main barrier=fence tag. This in itself is somewhat ambiguous, as the documented usage (and well over 99% of actual usage) is on ways, not individual nodes. That may be why different routers interpret it differently (i.e the interpretation could be “this is non-standard tagging so ignore it” or “someone has mapped some kind of barrier, let’s be conservative and assume no access”).

Given the Australia-specific usage, perhaps worth asking in an Australia-specific forum how these could be mapped if it is desired to do so, without producing undesired impacts for humans?

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I have dropped a message to bob3bob3 | OpenStreetMap who seems to have added many of these in AU. Given he is regularly on the road he may answer in a few days. At each Aussie location you are also likely to find Mapillary imagery.

Maybe a new tag like barrier=audible_fence rather than using barrier=fence at all, if that doesn’t break anything for data consumers using the current tagging?

5 Likes

I think some also have flashing lights. I think there have also been trials on guideposts that have both flashing lights and audio in attempt to prevent wildlife crossing roads. These are triggered by passing cars (slightly different to those identified above).

fence_type=audible?
fence_type=virtual_audible?
fence_type=sensory?

As sub tags with main tag barrier=fence, you mean? I think that still leaves the problem that data users have to look at a fairly obscure sub tag to know that these are not actually barriers for most users, and the documented implication of access=no does not apply. (I recognise that e.g. barrier=entrance has similar issues, but I think that’s more a well documented exception than a model to be followed).

A new tag as @rskedgell suggests does seem more likely to give useful results in most situations. But it’s possible I am missing a significance of these features for vehicles or humans.

4 Likes

The only thing you notice about these is the noise that they make as you go by. They do not have influence on driving speed and mostly have no change in road surface.
Maybe this would be an option.

barrier=cattle_grid
sensory=audible

In OSRM cattle_grid is in the white list (so not a barrier to traffic). The optional tag is just informative.

Mapping it as a barrier with a sub-tag is definitely troll tagging. Many routers will also treat unknown barrier types as unpassable.

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I only just drove through one yesterday. It was co-located with a standard steel cattle grid, but this isn’t always the case. There are also sites with a series of parallel steel or wire frame stock fences close to the road surface edge and of them some are one lane width. This “funnel” shape made I have seen of variable lengths (say) 4 to 50m long. They would tend to slow traffic although there is no legal requirement to. Those with associated flashing strobe lights are rare. I think I have only seen maybe 2.

There are also sites with the side parallel funnel fencing without the audible/siren device. Most if not all of the audible device sites have warning signs as the screaming noise is loud enough to distract a driver. They are setup to trigger on movement, most often with a velocity limit, so most vehicles will not trigger it.

I have had a few driving situations where kangaroos are caught in the funnel shape and have had to slow to avoid a collision. Some cattle grid sites are in bad condition enough to warrant extra “road work” speed limit signing that stays in place for years. Most back road drivers slow for cattle grids.

I believe that the audible devices are also intended to stop dogs/foxes/kangaroos/wildgoats, not just cattle/sheep.

To my memory I have only ever created a node and not a way for any parallel or cross metal fence.

The use of barrier=fence, sensory=audible was a suggestion on talk-au when I raised it there some years ago. I am not averse to changing them, but would need discussion/consensus.

My Garmin GPS navigation device routing with a Free maps for Garmin from OpenStreetMap OSM based map file is unaffected by the barrier, nor does it warn of them or cattle grids.

I see some of those posts starting here in August 2021 - although it sounds like that may have picked up from earlier posts.

The initial post was 19th April 2021. [talk-au] Audible stock control fences - mapping

This sounds like those annoying whining things that some people put in their front gardens to discourage wildlife.

I’ve been wanting a way to tag them for a while as they may be fine for people old enough to have trashed their high frequency hearing, but make public paths unpleasant for those of us boring enough to still have mostly functioning ears.