What phantom traffic jams can teach us about crowded Tube escalators

Have you ever stepped onto an escalator intending to walk up the left-hand side, only to find yourself trapped behind a wall of people standing still because a bottleneck has formed ahead?
And wished there were some way to make it clear?
As it happens, there is.
Oddly enough, the answer comes from the way traffic behaves on motorways.
Elizabeth line’s Farringdon station in the rush hour (c) ianVisits
Drivers have long experienced the curious phenomenon of crawling through a traffic jam, ex