Innovation: HDD Design Stress and Profile Analysis for Steel and Plastic Pipe

Our Water and Wastewater Transmission and Utilities team has developed new Horizontal Directional Drilling (HDD) software tools for route alternative analysis and design. The tools, which were successfully used for a force main project in Oklahoma, include an HDD Profile Calculator and Technical Toolbox HDD software that enables greater precision in various stages of the construction process for pipeline projects. The development of these tools recently won a Horizon Award, a quarterly award at Freese and Nichols given to projects that encapsulate our culture of innovation.

Vetting Options for HDD

Below is a snapshot of the HDD route alternatives developed using just Google Earth software to draw the layout, but also using both the HDD Profile Calculator and Technical Toolbox Software to verify it:

HDD route alternatives, showing Option 7 that was ultimately removed after applying our additional tools’ calculations.

Using a combination of Google Earth, HDD Profile Calculator, and the Technical Toolbox HDD software, our team was able to thoroughly review seven different options, then narrow them to two options as requested by the client. Notably, Option 7 (noted on the image above) was ultimately removed, though it appeared sufficient at first. However, after running our HDD Profile Calculator, our team saw that we could not get the minimum pipe depth required to use it.

Then, with the HDD profile calculator, we were able to narrow our options to two different alternatives, Option 2 and Option 6. Using the profile tool to analyze Option 2, we determined a 16’ deep bell hole would be required at our tie-in point. The profile calculator was able to show that the HDD had to be extended to gain sufficient depth below the river with the radius and entry angle shown (“Option 2 HDD calculations” below). This allowed our team to understand some of the construction issues we might face with this option.

Option 2 HDD calculations.

Evaluating Pull Loads and Stresses

The HDD software has a built-in tool that will upload route options allowing ground profiles to be incorporated for running stress and pull calculations. Calculations can be run for plastic or steel pipes.

Spreadsheets are typically used to run these types of calculations. However, our new tool offers new information not previously available. The software develops the profile, runs the calculations for the engineer, and provides a selection. It provides stress analysis along each point in the profile to help determine whether a profile will work for depth and obstructions, and what the stresses are. Additionally, it calculates the required pull loads, and determines the pipes maximum allowable pull load.

Verifying Contractor HDD Profiles

Using our tool, we have been able to verify HDD profiles for projects. Normally, to accomplish this, we use rules of thumb, CAD generated profiles, and spreadsheets. However, with the HDD profile calculator and Technical Toolbox Software we can provide precise analysis on profile and stresses.

Overall, our newly developed ​​​​​​​Horizontal Directional Drilling (HDD) software tools are nimble supporters to a range of design and construction needs in utilities and transmission projects.

For more information, contact Jonathan Faughtenberry,, 539-202-3239.