I sometimes watch a program on the educational network called “Mega-structures,” which generally shows how large structures are built. Two recent programs dealt with potential future mega-structures that will likely have a large impact on our world.
The first is the idea that the motor car will become obsolete and will be replaced by pods. In cities these pods will be connected to a system of overhead rails that will transport people to where they want to go. When you get in you give the destination and the pod will take you there, using GPS and its in-built knowledge of the network. The whole system will be like the pods that pick up and deliver goods in a huge warehouse, as in such companies as Amazon. The pods are controlled by a computer system that tells the pod what to do, but each pod has sufficient autonomy that it can find the best way to its destination. If there is an obstacle in its way, like a fallen package, it detects it and goes around it and also tells the central system that it is there so that it ensures other pods know about it. There are thousands of such systems working successfully in the USA, but most of them have hundreds of pods, even thousands, but not more. In order to run a huge system like a city-wide transportation system with perhaps hundreds of thousands of pods will require a significant upgrade of the control system. But, in effect, it is just an expansion of a working system, the basis is already there.
The other idea is that there will be a tunnel between Siberia and Alaska that will mostly transport freight from China and Russia to North America. The distance is ca. 62 miles, and this would be the longest tunnel in the world. Much of the tunnel will be made of pre-fabricated steel sections that will be assembled on the ice during the winter and when the ice melts the sections will be sunk to the bottom, and there connected together and then covered over with earth/sand. This is called a submersible tunnel and is much cheaper to make than drilling, especially thru rock. Such a tunnel would reduce energy use significantly since it will replace the need to use ships and planes to transport most goods from China and Russia to the whole of the Americas. There are many other places in the world where submersible tunnels could greatly reduce the time and cost of transporting goods around the world.