The only issue the builders of other regions would have is with the creation of the tunnels.
Tunnel work is being done by masons and farmers. The crafters are all focused on the laying track or developing the locomotive and cars.
Track laying shouldn't be an issue, as they already have the system for it with Minecart.
A track that carries hundreds of lbs in minecarts is one thing and a track that carries tones with a locomotive is quite another beast. They are about as similar as a house cat is to a mountain lion.
And because of the Duke, the process of building the Engine and the Cars can be achieved by any group of Crafters & Smiths (i mean a newbie like Karen was able to achieve it, though minus the mana capacity issue).
Karen is quite the special case. A year before the project ever came up, Miyabi taught her how to train her crafting skills. That with all the pressure put on her from the bathroom project and the winter green houses has made her more capable then the assistant she was before. Conversely dumping that load on a random Craftsmen job holder will only see them collapse in despondent ineptitude.
Keep, in mind, that Crafting is apparently quite a common Job in that world with hundreds or even thousands of people possessing it.
But because the concept of "train to get better in your Job" isn't known to the people, its causing the Crafters to not be able to do any decent work and only do low level work (like fixing fortress walls in dangerous conditions).
And other nobles will suddenly ignore a thousand year for precedence because their competitor claims that's how it was accomplished? More like they would believe that it's misinformation and try using existing methods to accomplish things in their own way.
So, while the whole process would be slower than under MC's supervision, the other regions should still be able to eventually get it set in a decent time.
Not just slower, but likely to be doomed to failure. Not only because people with mining experience can't be brought in, but because of all the extra little things Miyabi does to make it possible. Ignoring for a moment his ability to dig at walking speed, don't underestimate the power of good food and comfortable living and working conditions makes to a workforce.
Then even before you consider Miyabi's thinking process, you need to look at the game like mechanics that fundamentally change how he operates. Sure many miners might be able to make a straight and level tunnel, but could they do it at walking speed while storing the harvested materials at the same time?
Just train a crafter to do it you say? Pft... what insanity are you speaking. Even if they nobles believed it possible, it would take decades even for Karen to build up the capacity let alone some other noble's neglected and woefully trained wall repair crew.
Also the Duke was clearly being careful on not informing anyone about the existence of MC and his capabilities, and didn't inform anyone on how long the project took to complete. Meaning that, even if say it took the other regions to do the work in 5 years, it would still be a decent speed and considered fast.
O . o;
We reading the same manga? Because Duke Green Vale had the jumpedup tailor leak all the details to him in preparation for the ambush they attempted to pull on Duke Berdini.
So they know not only who is the architect, but also the main craftsmen behind the train tunnel plan. They know when it was proposed, when the concept was approved, and when they broke ground on the first tunnel and laid the first track. Giorgi was present at all the major presentations, and leaked it all to Green Vale.
Because of this its highly likely that the Duke won't be be asking MC to work on creating any new routes for other regions.
Even if he does ask him, it would primarily be for creating the tunnel (which technically any Crafters could do, if they train and increase their Mining abilities and Storage size, like how Karen did with her storage). And all the other aspects like creating the train to laying the tracks would be handled by the Crafters and Smiths (i mean, MC only worked on laying the tracks and creating the Stations, primarily because they were short on time as the deadline was approaching fast).
Nope, not any crafter could dig a tunnel at any speed that mattered. And training one would take decades. As I point out above, stone masons and farmers are being used to expand the tunnels Miyabi is digging. He is also collecting and processing the materials they and he are excavating and turning it into building materials for the tunnel walls. Sure other noble could just throw more workers at a project, but the loss in quality and working conditions would effectively kill any other project not led by Miyabi or a specialist team trained by him.
In the end, what the Duke wanted was to increase the prestige and scope of Crafters in the world as they are looked down upon by everyone without getting a chance to prove their worth. And with the underground railway system, which definitely needs atleast one Crafter, it is going to increase their value, even if it takes time for people to build the system itself.
Thing is, it will take decades for such a crafter to be trained up. Even the Third Prince, who is best placed to benefit from family connections was left untrained and neglected, so I would doubt there would be more then a handful of individuals scattered accrossed the kingdom who could even store a broom closets worth of materials, left alone properly construct said broom closet with their skills.
So while I agree Duke Berdini's goals have merit, they are long term goals that will take decades to bare fruit.