How To Calculate the Hydraulic Radius of Elliptical Pipe

Posted on July 11, 2022

One important element to understand when working with elliptical pipes is how to calculate the hydraulic radius of the pipe. Read on to discover more about elliptical pipes, what they are used for, and how to calculate the hydraulic radius of an elliptical pipe.   

What is an elliptical pipe, and what is it used for?

A reinforced concrete pipe, or RCP, is one of the standard materials used in drainage pipes, storm sewer systems, sanitation systems, and large irrigation projects. 

In comparison, the reinforced concrete elliptical pipe is ideal for areas where various constraints may prohibit the use of standard RCP. While elliptical pipe can provide structural design benefits for design engineers, RCP is still the more cost-effective solution in most applications. 

When it comes to elliptical pipes, there are both horizontal and vertical options to choose from. In most scenarios, horizontal elliptical pipe accommodates higher flow capacities at shallower depths. In comparison, vertical elliptical pipes are often used to accommodate higher flushing velocities at low flows. In addition, both vertical and horizontal elliptical pipe can be ideal substitutes for round RCP and arch pipe where various height or width restrictions are present. 

Some common applications for elliptical pipe include:

  • Storm drains 
  • Irrigation projects
  • Culverts
  • Sewer systems 
  • Outfalls 
  • Pedestrian tunnels 
  • Groundwater recharge systems 
  • Jacked or tunneled installations 

What is the hydraulic radius of an elliptical pipe, and why does it matter?

A hydraulic radius is important because it is one of the main properties that controls the amount of fluid discharge of a channel and its ability to move sediments. In most cases, a high hydraulic radius value indicates that the channel contains a lower volume of contact fluid and a greater cross-sectional area.

How do you calculate the hydraulic radius of a pipe? 

To learn the hydraulic radius of an elliptical pipe, you must know how to calculate a hydraulic radius. 

The following is the hydraulic radius formula


Overall, R, a measure of channel flow efficiency, is defined as the ratio of the cross-sectional area of fluid flow, A, to the length of the wetted perimeter, P.

Curious about how to calculate flowable fill? Check out our How to Calculate Flowable Fill article here.

Looking for more resources?

Calculating the hydraulic radius of an elliptical pipe can be intimidating. Luckily, AmeriTex Pipe & Products can offer robust project management for your elliptical pipe projects. We have years of experience in the industry and look forward to sharing our expertise and partnering with your company on your next pipe project! 

Contact us today for more information on our products and services. 

Take a look at some resources about what we can do for your team: