Bridge/Culvert Section Critical Velocity Override Option
There are many different methods for computing critical velocity. The methods used by the Office of Structures are as follows:
- ABSCOUR 10: For cohesionless soils, the recommended method is the modified Neill method described in the H&H Manual Chapter 11. For cohesive soils, the recommended approach is to use the method presented by Neill described in the H&H Manual Chapter 11 and illustrated below.
- NCHRP 24-20 method: Use the Laursen equation for cohesionless soils. No method is recommended for cohesive soils.
The user can override the critical velocity computed by the program by checking this option. This option is not recommend unless it is approved by the Office of Structures.
Suggested Values for Critical Velocity in Cohesive Soils
Neill - Guide to Bridge Hydraulics, June 2001