A roadside slope is considered "recoverable" if it is equal to or flatter than:

A roadside slope is considered "recoverable" based on its steepness, with the criterion that the steepness is equal to or flatter than a specified ratio. The recoverable slope ratio of 1 vertical unit to 4 horizontal units (1V:4H) is recognized as a standard that provides sufficient stability for vehicles that might unintentionally leave the roadway.

When a slope is 1V:4H, it allows for an easier recovery by a vehicle compared to steeper slopes. If a vehicle leaves the road, the flatter slope presents less of a risk for rollover and allows the driver more opportunity to regain control while attempting to return to the roadway safely. This characteristic is particularly important in the context of roadside safety and accident mitigation.

In contrast, steeper ratios—such as 1V:3H and anything steeper—pose greater risks for vehicles that depart the road, potentially increasing the likelihood of severe accidents. The consideration of ratios like 1V:8H or 1V:10H would be more favorable in terms of vehicle recovery, but anything beyond 1V:4H typically veers into a category where it's less favorable for vehicle recovery. Therefore, a slope of 1V:4H stands