Ideally you would want to do this all over Europe.
Ideally you would want to do this all over Europe.
Those are not nice things. Double decker trains take longer to load/unload than regular trains for only a small increase in capacity. Single deck trains can make more stops in the same amount of time thus serving more people, or they can take less time in the stops thus getting people where they want to be faster. Time is important to humans, anyone who says slow down to others has no idea how they live or where their needs are. If you want to slow down and smell roses that is fine: go to a park and do so - meanwhile a lot of people need less time on transit so they get more time at home with their kids (or whatever else they do in life)
Larger loading gauges are a good things for a lot of reasons, but the ability to run double decker trains is not one of them.
If the size of your blocks are an issue, then that is a problem worth solving. If you are can't fit in all those trains, then you need to build more track not try to compromise. Yes track is expensive, but if you can't fit all the trains then the passenger volume is high enough to support it. This likely requires better operations though and some people see a loss of their direct train and don't see how a fast (fast is critical!) transfer is overall better for them.