It appears they line up with almost each handrail post. This is common where I'm from to reduce any chance of top flange bending under guardrail loading.
I can't tell if the one at the column is the same as the ones at the handrail posts.
It looks like that center section of handrail is two "gates" that roll away from the center, supported by the handrail on either side.
In that case, the handrail on either side would be really beefed up to allow those center sections to cantilever out there.
Difficult to see from one photo but looks like it's just holding up that thin horizontal strip to stop the floor that's on top of the trusses from sliding off sideways?
They only seem to have three tack welds so not exactly "structural"
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