Vertical curves are provided where algebraic difference between grades is equal to or A. less than 2 mm/m B. more than 2 mm/m C. less than 4 mm/m D. more than 4mm/m

The correct answer is: A. less than 2 mm/m.

Vertical curves are provided where the algebraic difference between grades is equal to or less than 2 mm/m. This is done to provide a smooth transition for drivers as they travel over the change in grade. If the algebraic difference between grades were greater than 2 mm/m, it would be too jarring for drivers and could cause accidents.

Vertical curves are typically designed in a parabolic shape. This shape helps to create a smooth transition for drivers as they travel over the change in grade. The length of the vertical curve is determined by the algebraic difference between grades, the speed limit of the road, and the type of vehicle that is expected to use the road.

Vertical curves are an important safety feature on roads. They help to prevent accidents by providing a smooth transition for drivers as they travel over changes in grade.