I used to bike a lot, about 50-75 miles a week, so I post about cyclist stuff that I find interesting, and here's a map that shows how steep roads are - really helpful for cyclists that are judging their routes by the hills

 this example is of a town in New Zealand

https://www.reddit.com/r/MapPorn/comments/rz7mri/street_steepnessgrade_visualization_for_cyclists/

and if you want all the math, graphs, and stuff about cycling, also applicable to low powered vehicles like Model Ts, VW Microvans, etc see https://www.wired.com/2013/03/whats-the-steepest-gradient-for-a-road-bike/