Driveway Apron Max slope?

[AceNRC]

We are lowering flow lines on a residential street. It requires us to increase the slopes of driveway aprons and, in the opposite direction, 4 - 6’ of the road. We’re concerned w/ bottoming out cars, or them hitting their bumpers.

Where can I find info on this to determine my max slopes?

 

[bimr]

The state DOT would be a good place to start.

 

[civilperson]

The maximum slopes has no effect, the CHANGE in slope requires either a vertical curve or transition tangent to prevent bottoming. Graphical solutions are easy and sell the solution to owners; cut out vehicle templates to scale and place on proposed grade change plotted to same scale. The long wheelbase trucks and cars with hitches require the most length of curve. Crests are more critical than sags for center clearance, (sags are more critical for bumper dragging).

 

[AceNRC]

Thanks