Permits for overweight company vehicles

I read that now official and special transport involved in the elimination of the consequences of emergencies can travel with excess weight and dimensions in the region if the head of the regional military administration grants permission. But if you need to move across a bridge or other artificial structure, then it seems that you cannot travel without additional permission, even if you already have permission from the regional administration. How can I understand what permits drivers of such transport need to have so that everything is legal, and what to do if you need to drive across a bridge with excess weight?