street cleaner hierarchy

there is a secret hierarchical structure in existence on the streets of london. it relates to street cleaners. i like street cleaners and always shout a cheery hello to them on my walk to work. sometimes they even reply.
here is the starting point – a brush and a trolley on wheels:

once you have earned an upgrade you get a pushalong jobby with brushes. (some of these have seats which is a feature upgrade i think)

finally, when you have actually made it, then you get to drive in a proper machine with a windscreen and everything. this is a temporary vehicle. (maybe it moonlights as an occasional table)