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Compact SPUI (Grade/Overpass)

mathematically sound grade-highway SPUI (whole integer units!)

highway is x axis
road is y axis

asset is 40 units wide, 28 units tall
excluding ends, intersection is 30 units wide and 20 units tall (measured from node to node)
highway ramps are 2-lane one-way roads that are 10x3 units.
connecting to the road are ramps at 45° angles, 5x5 units.

highway uses the standard spacing (as used in the vanilla cloverleaf). highway slopes are only 6m, the shortest allowable by the game. level terrain strongly recommended.

if you use any of these spuis properly along with a carefully-constructed highway system you should be able to maintain a perfect grid with no wasted space or funny angles!