Uniform calculation of loading times and comfort

It is quite difficult to gather preciese data about vehicle loading times as well as the comfort level.
The latter is very vague, so a set of definite criteria to calculate these might be a good idea.

The issue names no files, tests, or entry points. First locate how vehicle loading times and comfort are currently represented and calculated in the pakset, then review the existing discussion before proposing definite criteria. Done means the project has an agreed, uniform method for calculating both values.

Written by the indexing model from the issue text.