Tackling Complex Shoring Challenges on the I-25 Over Comanche Road Expansion

How do you widen a highway, add new bridges, and keep traffic moving—all while working in tight spaces and around existing infrastructure? That was the challenge our team faced on the I-25 Over Comanche Road expansion project.

At DHC, we pride ourselves on helping customers find cost-effective, practical solutions to complex construction problems. Every project has its own hurdles—limited space, underground conflicts, or the need to educate reviewers on innovative methods. This project had all of the above.

The I-25 expansion called for:

• Adding new traffic lanes
• Reconfiguring on- and off-ramps
• Creating barrier-separated shared paths for pedestrians and cyclists
• Building new bridges adjacent to existing ones

As cities grow, so must their infrastructure. These projects not only add capacity but also provide a chance to inspect and upgrade aging systems.

To expand the highway, the customer needed to build two new bridges supported by four new foundations, located right next to the existing bridge foundations. The roadway sat about 35 feet above grade, which required four vertical retaining walls to support the elevated highway—all while maintaining three lanes of live traffic in each direction.

This limited space meant a traditional cantilever shoring system wasn’t feasible. Instead, we turned to a grouted tie-back bracing system, paired with soldier piles and lagging.

• Grouted tie-backs: Steel rods drilled 50–65 feet into the soil, grouted in place to engage dense soils.
• Soldier piles and lagging: Vertical piles with horizontal panels to retain soil, working together with tie-backs to provide stability.

On paper, this system seemed straightforward. But in practice, the site threw us a curveball.

The roadway beneath the highway crossed at a 30-degree angle, creating a conflict: some tie-backs near the existing bridge abutments would intersect the structures if installed as originally intended.

We explored several options:

1. Run tie-backs in line with the roadway → created conflicts and large resultant forces.
2. Angle tie-backs in opposite directions → required continuous walers, which wasn’t possible due to bends in the wall and utility conflicts.
3. Hybrid layouts → ultimately unworkable as wall geometry changed.

None of these provided a safe, constructible solution.

The breakthrough came from collaboration. A micropile contractor the customer had worked with proposed a specialized shotcrete wall with angled micropiles. This addressed the tricky geometry near the abutments, while we proceeded with our original tie-back and soldier pile solution for the rest of the shoring system.

The result was a hybrid approach:

• Micropiles and shotcrete where space and geometry demanded it.
• Tie-backs with soldier piles and lagging where conditions allowed.

The final design wasn’t the “pure” system we initially envisioned—but that’s the reality of construction: the right solution is the one that keeps people safe, meets project requirements, and minimizes risk.

In the end, the system wasn’t just a technical solution—it was a collaborative one. By anticipating problems before they became field issues, and by working hand-in-hand with partners, we were able to deliver a safe, cost-effective design that kept the project moving forward.

At DHC, we believe that the best solutions come from teamwork and a commitment to doing what’s right for the project.