Mass Transit Systems Face Social-Distancing Puzzle

Cities around the world are butting up against an intractable problem as they emerge from their coronavirus lockdowns: It is almost impossible to make their mass transit systems comply with social distancing during the rush-hour crush.

Keeping passengers several feet apart in buses, on train platforms and on board subways could reduce ridership by as much as 80{f08ff3a0ad7db12f5b424ba38f473ff67b97b420df338baa81683bbacd458fca}, according to officials and public transport companies.

Some…