Once upon a time there were priests. They served the public in “holy” places, mediating between the audience and the divine gods. This is how they actually made their money. This was their “job”. And the legal and educational systems made sure that this should be a steady job.
Priests were to stay “pure”. At least as viewed by the public. Otherwise, the gods might be angry at them and cause some earthquake or something. Hence, they were not allowed certain things, which you may guess. You guessed only a part of it: They were also not allowed near dead people.
In Hebrew, a priest is a ‘Cohen’. In fact, many people who carry this last name nowadays (or related names, such as ‘Kogan’, ‘Katz’ and others) are descendants of ancient priests.
Tiberias is an ancient peaceful town kissing the Sea of Galilee. As such, some locations within the town appear to contain old bones from ancient times. Still, new roads have to be built for the public.
But the “impurity” of these antique bones is not allowed to reach Mr. Cohen’s new Mazda passing by above the road! No problem. We have found a solution. Let’s spend 20 times the original cost of the road, and build it during several years on top of many specially-designed concrete bridges.
Now Mr. Cohen is safe, and there will be no earthquake.