The one full of explosives is a rolling bomb, the one in the video full of sand bags making is way in a minefield is looking like you say. Sand bags to protect the center fuel tank and prevent it from turning over.Wow, I just pu together the picture about the events in Vuhledar, and the strategy of the Russians.
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This is not a bomb, this is a demining vehicle.
The Russians send these on the road to blow up mines - ot loaded with air blast, non cratering munitions.
Most likelly the vehicle drive up and down on the target area, and if blown up then they send another one.
Afterwards they sent the units there, but in meantime the Nato trained units with Nato provided munitions mined with artillerythe road.
So, next time the Russian army will use remote controlled demining vehicles on the roads in the front of the convoys - that is the only way to make sure ther is no mines on the road.
It's still quite a dumb and expensive way to open a road, using a mine roller and plow in front of a vehicule would be way better... at least it would make a way longer path than just blowing itself up. It look like a desperate measure.