A quick google led me to this page, which tells me that the cost of moving dirt is a very complicated topic with its own jargon, and that the cost depends somewhat on the geology of the dirt to be moved, the slope of the ground in question, and, very importantly, the cost of the fuel required to run the earthmoving equipment.
However, one estimate on the page (dated 2007, so using 2007 diesel prices and driver wages) was $2100 for a 3000-yard ditch (assuming I understand the jargon correctly, that would be an eight-foot ditch (I don’t know if that’s width or depth, the word used is ‘cut’)).
A ditch, or an open-air mine, is also a lot easier than a tunnel because you don’t have to worry about the roof falling in on you (I understand properly shoring up a tunnel roof is another very complicated topic, which most certainly reduces the speed at which you can dig, which in turn means you’d need to keep paying your workers for longer to cover the same distance, thus adding a multiplier to the earth-moving cost)
There’s also ventilation, and pumping if you’re going to be digging below the water table. These are ongoing costs: you need to keep incurring them for as long as you want your tunnel system to remain viable, not just during the initial digging phase.
This page suggests that avoiding water during the mining process is yet another complicated and surprisingly expensive topic, and one that often requires exploratory digging before one commits to a major tunnel. I don’t know if transit systems handle it in the same way, but it’s worth noting that people tend to build cities at low elevations and near major bodies of water.
$21,000 per 3000 yards of tunnel is an eminently practical price for a city. $210,000 is $2100 per 30-yard-wide house. Dig big trench, lay down premanufactured tunnel pipe sections, close up trench. We’re not talking subways here.
$210,000 would strike me as cheap for a permanent above-ground structure of that size, never mind an underground one. Looked at another way, $2100 sounds about right for thirty yards of concrete storm sewer pipe but orders of magnitude off for transit—prefabricated tunnel sections big enough to drive cars through and strong enough to carry however many tons of earth or rubble would not be cheap to make or to move into place, especially if there isn’t an above-ground transport grid to carry them on.
A quick google led me to this page, which tells me that the cost of moving dirt is a very complicated topic with its own jargon, and that the cost depends somewhat on the geology of the dirt to be moved, the slope of the ground in question, and, very importantly, the cost of the fuel required to run the earthmoving equipment.
However, one estimate on the page (dated 2007, so using 2007 diesel prices and driver wages) was $2100 for a 3000-yard ditch (assuming I understand the jargon correctly, that would be an eight-foot ditch (I don’t know if that’s width or depth, the word used is ‘cut’)).
A ditch, or an open-air mine, is also a lot easier than a tunnel because you don’t have to worry about the roof falling in on you (I understand properly shoring up a tunnel roof is another very complicated topic, which most certainly reduces the speed at which you can dig, which in turn means you’d need to keep paying your workers for longer to cover the same distance, thus adding a multiplier to the earth-moving cost)
There’s also ventilation, and pumping if you’re going to be digging below the water table. These are ongoing costs: you need to keep incurring them for as long as you want your tunnel system to remain viable, not just during the initial digging phase.
This page suggests that avoiding water during the mining process is yet another complicated and surprisingly expensive topic, and one that often requires exploratory digging before one commits to a major tunnel. I don’t know if transit systems handle it in the same way, but it’s worth noting that people tend to build cities at low elevations and near major bodies of water.
$21,000 per 3000 yards of tunnel is an eminently practical price for a city. $210,000 is $2100 per 30-yard-wide house. Dig big trench, lay down premanufactured tunnel pipe sections, close up trench. We’re not talking subways here.
$210,000 would strike me as cheap for a permanent above-ground structure of that size, never mind an underground one. Looked at another way, $2100 sounds about right for thirty yards of concrete storm sewer pipe but orders of magnitude off for transit—prefabricated tunnel sections big enough to drive cars through and strong enough to carry however many tons of earth or rubble would not be cheap to make or to move into place, especially if there isn’t an above-ground transport grid to carry them on.