[DanWaterworth]

It may well be the case that they are all topologically equivalent, but they needn't be, so long as bridges are allowed. Perhaps that's how they could make F1 more interesting.

[alexkus]

Suzuka has a bridge:-

https://en.wikipedia.org/wiki/Suzuka_Circuit

[DanWaterworth]

Unfortunately, the presence of a bridge is necessary, but not sufficient. Think knots.