I would think Powder Mountain Road SR158 going from Eden to Powder Mountain Ski Resort 16% grade for 7 miles.
Steepest Road in the UK, Ffordd Penllech, Harlech
8%
The steepest road in San francisco
Herberton Street is a sealed road in Queensland.
Steepest is an adjective.
District Line - Bow Road to Bromley By Bow at 3.57%
Utah
About 3,050 road miles.
Scenic World's railway line is the steepest
The terrain is the steepest when it's on the left side of the map.
The Utah road use tax rate varies somewhat from county to county. It is about 0.30% in most counties and is called the highway tax rather than the road use tax.
Sacrament and Utah