This sign amused me. Back home we have cattle grids, here they have elephant grids. I suppose it is only logical, but it still rather tickled me.
Elephants can be extremely destrcutive to agriculture and even wild vegetation, so by keeping them within a designated area, the damage can be limited.
Tsavo National Park is divided in two parts: Tsavo east (the one I visited) and Tsavo west - in the middle lies the town of Voi. Although they bear the same name, there are separate entrance fees for the two parks. In 2003 it was 200 Kenyan shillings per vehicle and 27 dollars per person in Tsavo east - to enter Tsavo west you pay the same price. Not cheap, maybe - but wildlife is truly abundant - so I guess it's money well spent.