3 ms·
It’s pretty common to have these machines buried in the tunnel after they done the digging. These are usually custom made one off machines that don’t have much
by dogma1138 6y ago
It’s pretty common to have these machines buried in the tunnel after they done the digging.
These are usually custom made one off machines that don’t have much of a life span beyond each project.
That was on some level the whole point of the boring company Elon said it was crazy that these machines were discarded or sold for scrap.
That said since recovering them would be much easier than landing a rocket I don’t know if there is actually financial motivation to recover them.
When they are sold they are usually sold for their effective scrap weight (metal worth minus the cost of getting them offsite and breaking them down).
- baybal2 6y agoWhen the cost of machinery is a rounding error in the cost of the entire project... Yeah, I don't like that thinking.
- taneq 6y agoWhy not? It just means that the main expenses of the project are labour, materials, energy, etc. I don’t imagine the paint for the Sistine Chapel ceiling cost much compared with the cost of painting it.
- baybal2 6y agoIf recovered, the cost of the machine would likely repay the recovery operation many times over even if scrapped. What I don't like is the thinking of people who rush for the sign off, and paycheck date.
- dodobirdlord 6y agoWear and tear on complex machines is killer. It shows up in an onslaught of tough to diagnose and expensive to solve issues at the end of operational life. The borers are probably engineered for an operational lifetime only a safety factor longer than the tunnel they will dig.
- dogma1138 6y agoThe cost of those machines failing or worse getting stuck is enormous, they have very specific life span and are pretty much discarded even mid project if they dug past their mileage. These machines are also custom built for the diameter, soil type and probably a plethora of other variables so it’s unlikely that you could reuse them. They are also not built to be recovered and reused from what I gather which complicates things further.
- baybal2 6y agoHmmm, doesn't seem so at all
- dogma1138 6y agoDoesn’t seem what?
- baybal2 6y agoDoesn't seem real. What's there to break? The cutters on the face of the TBM, and bearings would likely be replaced few times during boring. Aside from that, what's there to break? Hydraulics is sure to outlast even the longest boring. Pumps, gearing, sealing, etc should all be easily replaceable.
- dogma1138 6y agoThere have been plenty to cases where these things have broken down which caused years of delays and usually another tunnel had to be dug to get them free, sometimes they changed the path of the original tunnel to circumvent them where it was possible and more cost effective. These machines are constantly serviced and aren’t operated one minute past their life spans. I really don’t think you understand how many hours these things operate for.... To put things into perspective machines have a single digit meters per hours top speed and not high single digits to boot, and if you are digging in rock you are looking at sub meter per hour figures. If you have a source to contradict this I’ll be happy to read it but honestly every source from articles to documentaries pretty much paints the same picture these machines aren’t worth their weight in scrap once they are done with.
- barking 6y agoIf it's not causing pollution from leaks or whatever and it's effectively worn out then you could view it as being as good a place as any to store something that someone could later salvage for its scrap value. I remember someone saying similar about plastics (I think). That if we just stored those plastics we can't effectively recycle until such time as it is possible, it would be a greener solution than e.g. incineration
- roenxi 6y agoBreaking big rocks into smaller rocks and then carting them out of a tunnel is already very expensive. It is better that the cost of the machine isn't important.
- Gibbon1 6y agoI saw in a paper that gave reasons tunneling projects were expensive listed labor as a larger fraction than you would think. Consider cars. Your $30,000 car probably costs $60,000 to operate over it's life. Likely more. Not surprise me if tunneling is the same. Operating costs dominate. Then consider the Bertha problems in Seattle. Two year delay because they needed to dig a rescue pit to get at it after it broke down. Ask would you want to start a tunnel project with an 'used' TBM? Likely not.
- deleted 6y ago[deleted]
- Reason077 6y agoA TBM cutter head that was used to tunnel under the Thames now forms the station art at Cutty Sark DLR station.
- samizdis 6y agoPicture of it here: https://commons.wikimedia.org/wiki/File:TBM_Cutter_Head_at_Cutty_Sark_DLR_station.jpg https://commons.wikimedia.org/wiki/File:TBM_Cutter_Head_at_C...
- stormdennis 6y agoNeed to lose those disgusting shower tiles though.
- postingawayonhn 6y ago> It’s pretty common to have these machines buried in the tunnel after they done the digging. People say this all the time but as someone who tends to follow quite a few tunnelling projects I can't recall one in recent memory. Typically TBMs are scrapped or returned to the manufacturer for refurbishment.
- gsnedders 6y agoAt least two of the Crossrail TBM shields were buried: https://learninglegacy.crossrail.co.uk/documents/c300-western-running-tunnels-caverns-project-tbm-shield-burial-backup-removal-2/ https://learninglegacy.crossrail.co.uk/documents/c300-wester...
- postingawayonhn 6y agoInteresting, I hadn't heard about that one.