Chapter 4 - Elements of Design

4.3. Vertical Alignments

4.3.5. Maximum Changes in Vertical Grade without Using Vertical Curves

GDOT typically uses vertical curves for changes in vertical grades. However, there are situations where it is either impractical or impossible to utilize a vertical curve. Such situations include:

• temporary vertical tie-ins

• profile tie-ins such as overlay transitions

• avoidance and/or minimization of an environmental impact

• point profiles in overlay and widening sections

• profile reconstruction near fixed objects such as bridges and approach slabs

Table 4.7. Maximum Change in Grade that Does Not Require a Vertical Curve lists the maximum vertical grade changes that do not require a vertical curve. Note that these values change per design speed. Grade breaks should only be used when necessary (vertical curves should be used, wherever practical). If two or more of these vertical grade breaks are utilized in succession (i.e., a point profile), the cumulative effect of these grade breaks in the profile shall be evaluated for stopping sight distance and it shall be verified that typical stopping sight distance is always provided. If the cumulative effect of a series of vertical grade breaks violates stopping sight distance criteria, the values in Table 4.7. may need to be reduced.

Table 4.7. Maximum Change in Grade that Does Not Require a Vertical Curve
	Design Speed (mph)
	20	25	30	35	40	45	50	55	60	65	70
Maximum Change  in Grade (%)	1.20	1.10	1.00	0.90	0.80	0.70	0.60	0.50	0.40	0.30	0.20