AASHTO Vertical Crest Curve

Purpose: Use this calculator to estimate the minimum required length and K value for a crest vertical curve connecting two vertical tangents, based on the selected stopping or passing sight-distance criterion.

How to use: Select AASHTO Stopping, RCOC Stopping, or AASHTO Passing. The calculator applies the matching sight-distance table and default heights automatically. Then enter the initial and final tangent grades plus the design speed. If needed, you can still edit the eye and object heights manually for a custom check.

Select Sight Distance Type

AASHTO Stopping Sight Distance RCOC Stopping Sight Distance AASHTO Passing Sight Distance

Height of Driver's Eye (feet):

Height of Object (feet):

The heights in the calculations above should match the sight distance of interest. RCOC SSD: h1 = 3.5 ft, h2 = 0.5 ft. Passing: h1 = 3.5 ft, h2 = 3.5 ft. AASHTO SSD: h1 = 3.5 ft, h2 = 2.0 ft.

Crest vertical curve check: the initial tangent grade should be greater than the final tangent grade (`g1 > g2`).

Initial Tangent Grade, g1 (%):

Final Tangent Grade, g2 (%):

Design Speed (mph):

Algebraic Grade Difference, A:

N/A

Required Curve Length, L:

0.00 ft

K Value:

0.00

Method Used

N/A

AASHTO Vertical Crest Curve

Google Earth Pro (Desktop) Steps

Algebraic Grade Difference, A:

Required Curve Length, L:

K Value:

Method Used

Algebraic Grade Difference, A:

K Value:

Maximum Supported Design Speed:

Sight Distance Used:

Method Used