Have you seen Shanghai’s roads? Some of the high ways are
double, triple and quadriple layered. Just like Keppel flyover and
the new flyover over the roads at world trade centre. Shanghai even
has elevated round abouts. The bridges in some US states are also
double layered, like bay bridge and golden gate. Perhaps that may
be the way to go. Double layer our highways. That will make it at
least 6 lanes each way.