The bigger question to me, is why doesn't the US do combined gas/electricy/... trenches accessible by manholes, like you can see in most northern European cities? Is it just economic shortsightedness or does it have to do with density (or rather US cities being the opposite of dense)?

(yes there are regulations on minimum distance between electricity and gas pipes, so these trenches have to be pretty big)

> Hmmm, how does the gas company afford to bury the gas pipes then ?

According to Wikipedia, pipelines tend to be buried because soil acts as a thermal insulator, thus reducing thermal fatigue and consequently maintenance costs.

Electricity isn't transported through pressurized pipes, thus it isn't subjected to the same constraints.

Overhead gas lines aren't an option.