So, two of my interests are tagging waterways and highways. And of course, where they intersect, there is often a bridge. Here is how my bridge tagging method has progressed over time:

• Bare minimum - split the highway (using e.g. aerial imagery), set bridge=yes and layer=1. This is conventional, if not particularly informative.

Then I found the National Bridge Inventory, which contains not all, but certainly many of the significant bridges in the USA. This data is quite interesting, it includes detailed info on the bridge structure and its integrity.

One can use this to verify the length of the bridge as drawn on the map, in many cases what’s shown in aerial imagery matches to within 1-2m of the specified length. You can also find data on when the bridge was constructed or rebuilt.

• Added context - add start_date tag.

Today, I was thinking, it’s not much more difficult to add an area object for the bridge structure itself using the man_made=bridge tag. In fact, one could then move such tags as start_date and bridge:structure into the separate object.

There is also an existing bridge:ref tag which is loosely defined. Here’s my idea. What if we used the NBI structure/bridge number, where available (in the USA)? You might wonder why that would be useful. Well there is a site https://bridgereports.com, which parses the NBI database with some additional refinements, and displays a nicely formatted summary. A plugin might use the structure/bridge number to display such data.

Something like the following. For the highway:

bridge=yes
highway=secondary
layer=1
ref=KY 218

And for the bridge structure [edit: updated per discussion in comments]:

ref:US:nbi:state_code=21
ref:US:nbi:structure_number=044B00032N
structure=beam
layer=1
man_made=bridge
start_date=1978

Here’s how the metadata could be displayed (using bridge ID “044B00032N”): https://bridgereports.com/1211803