Case Study: Denver I-70 Viaduct Design Flaws Cause Rework and Delay (2020)

Project Overview
• Name: Denver I-70 East Viaduct Replacement
• Location: Denver, Colorado
• Year: 2020
• Project Size: $1.2 billion
• Scope: Replacement of aging highway viaduct with new elevated structures
• Lead Agencies/Contractors: Colorado DOT, Design-Build Contractor

Category of the Issue, Problem, or Challenge
• Design
• Structural Engineering

Summary of the Issue, Problem, or Challenge
During construction, discrepancies between design specifications and field conditions resulted in significant rework of structural elements. Design flaws included underestimation of foundation load requirements and insufficient detailing for seismic resistance, requiring redesign and delay.

Root Cause Analysis

• Inadequate geotechnical data integration into foundation design.
• Insufficient seismic load consideration in structural calculations.
• Lack of constructability review led to design details not aligning with field realities.
• Communication gaps between design engineers and field teams.

Impacts Due to the Issue, Problem, or Challenge
• 6-month project delay due to redesign and rework.
• Cost overruns estimated at $8 million.
• Increased safety and quality assurance scrutiny.

Corrective Actions Taken

1. Conducted detailed geotechnical reassessment and updated foundation designs.
2. Revised structural models to incorporate seismic loads per updated codes.
3. Instituted cross-disciplinary constructability reviews during design phase.
4. Enhanced coordination protocols between design and construction teams.

Lessons Learned

• Comprehensive site data must be fully integrated into design early on.
• Seismic and other environmental loads require rigorous assessment and updating.
• Constructability reviews prevent costly on-site design conflicts.
• Strong communication between design and field teams is critical.

Audit & Prevention: Project Control Questions to Ask on Future Projects to Help Control the Situation

• Are site conditions fully captured and incorporated in design?
• Have seismic and environmental factors been rigorously evaluated?
• Is there a formal constructability review involving construction input?
• Are design changes promptly communicated to all stakeholders?