Great Works: Transcontinental underground Canal

Hello all

My current saga has a trader magi who is interested in creating an underground canal going all the way from Lubeck in the north of Germany to Geno on the Mediterranean coast.

Obviously such a canal, under that Magus' control would be insanely profitable for shifting goods, perhaps even more so if he allowed others to use it and charged tolls.

But how to achieve such a massive engineering work?

Lubeck to Genoa is about 1,060,000 paces (1060km). So thats our distance sorted. We'd want a tunnel wide enough to have two seperate canals, allowing travel in each direction, so maybe 5 paces wide for each canal, plus a pace wide raised wall between them and paths on either side of two paces width, so that's 15 paces across. Height, you'd want it to be about 4 paces high from the water level, maybe two paces deep, so 6 paces high. This means that each pace in length of the tunnel is 90 cubic paces of space. This will be important later.

How to make such a tunnel? With Perdo terram, you can destroy a cubic pace of dirt at touch range at level 10 (base 3, +1 to affect stone, +1 touch, +1 part). Add two size magnitudes to put it up to 100 cubic paces of stone and you can bore one pace of the tunnel with a level 20 spell. This would require 1.06million castings to complete. It would also create a tunnel that isn't necessarily stable. We'd need further spells to create pillars in the central wall dividing the canals to hold the roof up, and maybe additional supports. If we bumped the level of the spell up to 40, by adding another 4 magnitudes of size, we could bore a tunnel 10,000 paces long. Much better. This would only require 106 castings. Which is a lot, don't get me wrong, but not crazy for something this epic. Knock it up to 50, make it a ritual by adding two more size reqs and you've got a tunnel bored in a single spell 1,000,000 paces long (close enough to get close to genoa if you make sure you have a really straight direction, lets not quibble about a mere 60km.

All this assumes that we are digging through bedrock of course.
It also leaves the following problems to resolve

  1. Air. You need some or all the people working the canal boats will be dead by the time they reach genoa/Lubeck
  2. Water. Boats tend to work best on water, you'll need lots.
  3. Way stations. Even with a magically powered canal boat, 1000km is a long journey, you'll need spaces to park the boats up, rest the crew, sleep, etc.
  4. Lighting. People work better in the light and don't get as terrified
  5. Security. Earth dwelling faeries, jealous local rulers, rival magi. A project this epic will need protection and alliances.
  6. Access. If something happens in the canal, you need to be able to access it close to where the trouble is rather than potentially travelling 500km from one of the entrances.
  7. Arrangements with fellow merchants. A tunnel like this is going to be fantastically profitable. Other merchants will absolutely want in on it. It would be very hard to keep it quiet and also shift large amounts of goods. Maybe best to get other merchants onboard by allowing them either access with a fee, or maybe even start a joint company with some other powerful merchants, a trading coster specifically to handle the cross continental trade, create a monopoly and trust in the wealth and power of your coster-allies backed by your own magic to see off any potential rivals.

So, what other ways could this canal tunnel be fashioned? And how could we get around some of the problems? And are there any other problems I've missed?

On the water front, I think you could do it with four enchanted items.

One item creates a spring of water with a low rate of flow. You mount one copy of this at one end of the canal emptying into one side of tunnel. You mount an identical item in the other end of the tunnel in the other canal. Both canals are now filling from one end.

In the opposite end of each canal you mount an item that destroys an amount of water at the same rate as the spring is creating it. This only gets put into the canal when it is full. Et Voila! You now have a current in each canal going in opposite directions. The current helps propel your canal boats without any other agency but is slow enough that boats can be safely stopped and moored without being swept away.

If the tunnels ever spring a leak, all you have to do is seal the leak, remove the perdo aquam items for a while and let it fill itself up again.

Head of the Canal
R: Touch, D: Sun, T: Ind
This brass statue of a waterskin stands slightly above the waterline of the canal. It has a stopper that dangles on a chain beneath it. It creates a steady stream of water as long as the stopper is not attached to the mouth of the waterskin. Note that this is not a continuous effect. It stops at sun down and sun up and then immediately starts again. This restarting only triggers if the stopper is unstopped.
Base 4, +1 touch, +2 sun, +3 levels for environmental trigger - sun up/down, +1 two uses a day)

In advance, please excuse what might seem 'overly negative'. But this is world-altering stuff, so it's going to be hard!

  1. You're potentially dealing with multiple Tribunal cases - in multiple Tribunals, that is - worth of 'interference with mundanes'. Roman, Greater Alps, and Rhine specifically come to mind, just off the top of my head. Given the sheer number of simultaneous feathers to be ruffled, you'll need to secure massive political support before starting the actual project.

  2. Vulnerability to attack: Part of an inherent problem with a project of this scale is the scope of the area you have to be able to effectively defend. You've identified this as a need, but in terms of sheer scale, it's a big one. Given the relative skinnyness of the canal, it's fairly easy to collapse a few sections, and given its scale 'hostiles deciding to move in and enact their own tolls' of various kinds is likely to be a recurring possibility. You'd probably have to invent a new version of the Aegis of the Hearth - maginot line? - just to handle the magical creatures.

  3. I'd say you're looking at a minimum magnitude ritual in the 60s on the low end, rather than the 50s as you mention, and it'll likely take multiple castings. Additional magnitudes will be needed for 'fancy effect', increased size for height and width, (the canal you've suggested is very skinny/not high in height) affecting metal (at least somewhere in that canal is some metal you have to go through). You might need additional Technique Requisites - I'd honestly lean towards a giant Rego/Muto Terram than Perdo here. Otherwise any hole in the ground you make is going to be incredibly unstable structurally and quickly collapse before you can reinforce it properly. This is probably eminently achievable, since any magus this ambitious in terms of large scale physical works is likely a Terram specialist with a relevant magical focus.

  4. The PC could attempt to try this on a smaller scale, making a few key tunnels that help avoid nightmarish geographical obstacles, shaving weeks of travel time. It'd be a classic addition of a Roads Hook and increasing the covenants' income from local tolls, as they have the new 'best route', though the bandits or other nobles who find their toll money decreasing might take exception... There are some interesting plot threats in the Rhine Gorge section of GotF that could relate to this idea.

All in all, for simple trade route control/creation, it might be 'easier' to create some unregistered Mercere Portals.

With a duration of sun you might not even need a pe aq item at the end- given this rate of water flow (and assuming this canal is not very steep) how far will it get in a day? If it is flowing 1060 KM/day (with the duration definition being 12 hours) then it is moving at 88 KPH, and that would be the leading edge as all the water would disappear at sunrise or sunset and then the channel refills....

as a note. natural rivers seem to have a top speed of water flow at around 7 MPH, well under 88 KPH. In fact you could probably use moon duration, the leading edge of the water assuming 7 MPS would travel 4872 miles and the canal would only empty once a month- at that point you would probably need a PeAq at the far end...

Regarding building the tunnel itself, you can also find useful information in Hermetic Projects: The Tower. There are various spells and minor magical items that can be used to huge construction work. It also gives information on how to support the tower, that you can use to find out how to prevent the tunnel from collapsing. There are also spells to support the life in the tower which can be adapted to the tunnel: scrying system (the Stone Watchman and Projecting the Watchman's gaze), the Endless well to suppy water constantly, and finally story plots.

For such a long distance, the issue will be to keep it straight(ish) and at the same level. Magic itself cannot guarantee that, so you probably will need the help of a mage knowing hermetic geometry and able to use Line range. And with a decent skill in Architecture or Mining to solve the collapsing risks issue. Probably some form of magic will be required to make sure that the mage in charge of the digging keeps it bearing and remain accurate. That might be a good reason not to go for a single unique spell to dig the whole gallery - by the way, if you don't see the end target, how far can you dig ?
You will have no choice but to take in consideration the curvature of the globe, so it might not be possible to build it as one single, continuous channel, but instead you might have to consider to gate system to control the water flow. It all depends on how much magic you want/can afford to put into the build.
Do you want the barges to be propel my magic ? Do you want also the light to be magic - to prevent underground fire, air poisoning and suffocation ?

Digging the tunnel might be the easiest part - from a magical point of view:
Let's stick to a 1 km long tunnel at a time (level 35, very manageable by most mage with decent Arts without being over-specialised).
If you consider geometry calculation, strenghtening of the tunnel with other spells (Re/Mu Te), you can probably proceed to dig 10 km a day (1km/hour). Within a season your tunnel is done, assuming no issue during the digging.
So it shows that the issue is not the technical/magical feasibility, it is more the unpredictable aspect of it: are you crossing some faerie/infernal domains ?

Because you are going to build it across the bedrock, I would believe it will be deep enough to be safe from any mundane threat.

About issue with other merchant guilds will depends on how much you used the tunnel. Is it noticeable or does the marchandise transitting through this tunnel only represent one hundreth of the total volume of the goods received in the town ? If it is small enough, only the few business dealing specifically with the items might noticed it. If it starts to be 10% of the total business, then yes, every business will be impacted and people will be looking for the source of these goods.