Canals

Boats are the most effcient form of transport. 
So why don't we use rivers and canals more often?
For a start they are slower, but I don't think that has to be a deal breaker for everything.
Another reason is that the infrastructure is either mostly antiquated or doesn't exist, this can be rectified.
I think the biggest problem is river and canal size boats are much more labour intensive for they amount they carry than lorries or trains because of the limited size and their lack of speed.
However I think this is solvable, we can make self-driving cars that almost work properly, there are self driving cars that do work properly in the right enviroment but for a big chunk of the time get controlled remotely.
A self driving river craft, is a less difficult technical challenge, rivers and canals especially are less complicated to navigate than roads, boats travel slower than land vehicles allowing more time to make calculations and less danger when things go wrong.
A self driving craft could travel for nearly 24 hours a day, stopping only for maintainace checks and to change batteries.
Of course there would need to be people keeping an eye on everything and dealing with locks and so forth, but with a reasonable amount of traffic and a smooth running system they could be pretty economical to employ.
Empty boats could be hailed with an app, stop at desginated places to give rides as a way of supplementing income.
Ideally canals should be wide enough to carry boats with shipping containers, but existing canals can be modified and new canals can be dug.
Canals often require water to be pumped, but with the use of reservoirs that can be done using renewables when they are producing energy not required for the grid, (which they tend to do...).
Canals are often useful for drainage and irrigation, they are good for wildlife and if they come with footpaths people tend to like them, all of which is more than can be said for roads.
Or course any canal network could supplement and be supplemented by the global heat pump network...