Do you ever get the feeling that the ground beneath you is not solid?
When I drive over the bridge heading into Hamilton I often ponder whether the bridge will hold us and if not, how the kids and I would escape from the car in the water. I know this is an irrational thought given the engineering that went into creating that bridge. Driving around Toronto these days can carry similar concern. A huge sinkhole has opened up at Keele and Eglinton that has the road down to two lanes instead of four while the hole is re-filled.
A sinkhole in a street is generally caused when water from a broken water main or an underground river washes away the ground underneath the pavement, causing a void. At some point the pavement falls into the void that used to be covered by soil or rock. It is like icing on a cake where you eat the cake and are left with only the icing shell perched on nothing beneath. When this happens, it makes me wonder about the safety of all the other roads in the city.