You can't reach 90+km/h if you mix blue and green car flows in the north-east corner of the level.

This is the only principal difference between original and modified layout.

I've got this:
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3470379195

The score for fast configuration (in my example) was 775, for original configuration (in your run) is 778, so they are comparable.

I definitely could save some concrete here and there, and you too, probably.

The fast one is usually more complex and more difficult to optimize, so I don't advocate for it.

It's just to show that both ways of developing this idea are still on the table. We don't know yet, which has higher limit.

Yeah, if the extra speed can be achieved with smoother curves and going the way I draw them, then 800 should be pretty easily doable. You can even increase the concrete usage to 3500tons and still get the 800 points which does not sound impossible to me.

Yeah, if I compare my variant to yours, I have 91 km/h, but I paid 74 tons for each and every extra 1 km/h. Probably too much. :)

Still, I think 84 km/h is somewhat too modest of a flow for this layout. It should be faster.

And even better score:
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3470053819