Would subways around the world need to update current subway systems to handle increased passenger counts?

Yes, subway systems would need to be upgraded. These locations would need to add subway cars and modernize subway stations. Many stations would require additional entrances and exits at most station stops. It would be the goal, if possible, to enter and exit each subway station at the same speed prior to the beginning of Park-n-Rail_™.

In Washington DC for example, Metro is discussing the need to add capacity by adding an additional subway line under the Potomac River. This would certainly help with the increased demand in the Washington DC area and would certainly help when introducing Park-n-Rail_™.