Well you just made a pretty unfair comparison since you added up to 64000 for all four lanes vs 100000 people /per track/ on a 4-track railway. But I think your assumptions are all pretty optimistic. You wouldn't be able to run cars that close together on a multilane roadway because cars would need to move between lanes to enter and exit which would cause pipeline shocks if there was that little room.

Anyway the main difference between my claims and yours is that yours are speculation, while mine are based on history. We've seen five million people disembark at actual railroad stations. It's happened. We don't have to speculate.