[mersar]

If I was to guess (and thats assuming they actually exist, I haven't heard of them before) but I'd probably say they would be for utility use and probably be fairly small. Similar to the several kilometers of tunnels running below the U of C campus (though those are all concrete) that a lot of the phone, network and heating systems run through. The LRT tunnel that exists off the south line under city hall only extends a short ways past the municipal building underneath Olympic Plaza and thats as far as it goes.