When a bridge has entered the age of a sufficient plan, a bridge will ruin, but sometimes a bridge is ruined not because it has reached the age of the plan, but the ruins are caused by several factors.
Looking at the picture above, you can imagine what happened, my analysis, the bridge on the picture was ruined or broken on the floor until the gelagarnya was caused by dead load. seen above there is a pile of rock so laid deliberately so as to make the bridge was broken, because unable to withstand the load according to plan.
Another analysis is the possibility that the traffic that occurred in this area is light traffic, that is, planning on this bridge may have been only planned for the loads that are consistent with the traffic that often cross this bridge, but in fact what happens is, this bridge is often crossed by a vehicle which is very heavy, so that the load carrying capacity of the bridge is not sufficient to receive it, consequently, the bridge occurred destruction, broken and collapsed.
I took this photo from an inland village, not on a road or a national road, it is proper that it collapses, because those passing through the road are mostly unfeasible vehicles to cross this bridge, for this bridge is able to accommodate the load of vehicles that have 6 wheels, happens is a vehicle that has more than 6 wheels, so it breaks and collapses.