I-35 Capital Express South | Austin, Texas

EFCO’s Innovative Solution for Capital Express Supporting 140,000-pound structures over active highway traffic

Austin, Texas

Transforming Austin’s Busiest Corridor

The I-35 Capital Express South project represents a landmark achievement in construction engineering, solving the challenge of building massive pier caps while keeping one of Texas’s busiest highways operational. This 8-mile project is transforming one of Austin’s most congested corridors, adding three lanes in each direction to improve mobility for the growing region. The project includes critical infrastructure from SH 71/Ben White Boulevard to SH 45 Southeast. The signature elements—massive pier caps spanning active traffic lanes—presented engineering challenges that required Innovative solutions. With bumper-to-bumper traffic constantly flowing beneath the construction zone, traditional formwork approaches weren’t viable.

Partnership Built on Engineering Excellence and Integrity

Fluor Heavy Civil, LLC, a contractor with deep engineering expertise, partnered with EFCO to overcome the project’s unique challenges. The most prominent obstacle was supporting enormous 88-foot-long, 20-foot-tall pier caps that extend over one and a half lanes of traffic in each direction. EFCO proposed an advanced Tension Compression (TC) formwork system combined with custom-designed elements created from off-the-shelf products. After reviewing the Innovative design specifications, Project Director Mike Ortiz praised EFCO’s approach and commitment to Integrity, noting that the solution expanded his vision of what was possible in highway construction.

Eliminating Ground Supports for Uninterrupted Traffic Flow

The formwork for each cap weighed approximately 140,000 pounds and was supported by a single 18’ × 6’ column. Traditional approaches would have required extensive guying to prevent overturning and resist wind loads. EFCO’s engineering team developed a solution that eliminated the need for ground-based supports beyond the main column. They designed push blocks—specially engineered bracing components—that used the existing column as an anchor point, creating forces to counterbalance the massive weight of the pier caps. This self-contained system maintained all traffic lanes open during construction, reducing labor costs and construction time across all 78 pier caps in the project.

Doubling Capacity with Revolutionary Tension Compression System

EFCO’s new Tension Compression (TC) formwork system functions as a strength multiplier that effectively doubles the capacity of standard formwork when attached to both top and bottom components. This engineering breakthrough allowed for spans that would have been impossible with traditional methods. For context, standard SUPER PLATE GIRDER® formwork maxes out at around 2400 foot-Kip (a measurement of load-bearing capacity), while the Tension Compression system delivers 4100 foot-Kip—a 70% increase in strength without increasing the physical size of components.

Creating Custom Solutions from Standard Components

Demonstrating their commitment to Innovation, EFCO created a custom shore using standard POWER TOWER 50® (PT-50) components to support the massive structures. This ingenious adaptation delivered 2700 foot-Kip per leg, providing sufficient strength to bear the weight of the concrete pier caps during pouring and curing. Using modified off-the-shelf components, EFCO eliminated lengthy lead times while delivering the necessary strength—a combination no other forming company could match for this project’s timeline and specifications.

Maximizing Efficiency with Quality All-Steel Custom Components

While the structural strength of the system was key, EFCO’s approach also demonstrated a commitment to Quality and efficiency throughout the project. With the foundation of a reliable support system established, the team turned attention to optimizing the construction process itself. They meticulously
planned every aspect of the formwork installation and removal process to maximize productivity.

The project’s scale—161 concrete structures to complete with limited work windows due to nightly traffic management requirements—made cycle time a critical factor in success. EFCO addressed this by providing four sets of bottom forms and two sets of top forms, creating an efficient construction sequence where concrete pours could proceed on some caps while rebar cages were assembled for subsequent ones. The form design eliminated wood completely, using all-steel custom components for every detail, including the distinctive “longhorn” shape integrated into the caps. The lower-form sections alone weighed 27,000 pounds, highlighting the scale of this engineering challenge and EFCO’s capability to handle it.

Why Fluor Heavy Civil, LLC Chose EFCO

Fluor Heavy Civil, LLC selected EFCO because of their ability to think beyond conventional formwork approaches. The Capital Express project demanded a partner who could deliver Innovation and practical solutions to extraordinary challenges. EFCO’s engineering team anticipated potential issues before they arose, developing systems that maximized efficiency while maintaining the highest Quality standards.

The custom shore system’s ability to support massive concrete structures without restricting access or traffic flow demonstrated EFCO’s Super Service and commitment to helping customers achieve the Lowest in-Place Concrete Cost (LIPCC). The success of this partnership has led to EFCO being selected for two additional major infrastructure projects in the Texas region—the I-35 NEX project in San Antonio and the I-35E phase 2 project in Dallas—proving that when contractors face seemingly impossible formwork challenges, EFCO delivers solutions that transform what’s possible through their core values of Quality, Integrity, Innovation, and Super Service.