Case Study: Atlanta I-285/I-85 Interchange “Spaghetti Junction” Design Rework (2019)

Project Overview
• Name: I-285/I-85 Interchange Reconstruction
• Location: Atlanta, Georgia
• Year: 2019
• Project Size: $750 million
• Scope: Major interchange reconstruction with new ramps and flyovers
• Lead Agencies/Contractors: Georgia DOT /

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

Summary of the Issue, Problem, or Challenge
During construction, design errors in ramp geometry and clearance led to partial demolition and redesign of ramp sections. Errors were linked to inadequate design verification and failure to consider updated vehicle size standards.

Root Cause Analysis

• Insufficient design checks against current AASHTO vehicle and clearance standards.
• Limited 3D modeling and clash detection in initial design.
• Failure to engage traffic engineers early to validate ramp functionality.
• Incomplete design review processes lacking constructability focus.

Impacts Due to the Issue, Problem, or Challenge
• 7-month delay to reconstruct affected ramp sections.
• Additional costs of approximately $15 million.
• Traffic disruptions and public dissatisfaction.

Corrective Actions Taken

1. Comprehensive design validation against updated standards and codes.
2. Integration of 3D modeling and clash detection tools.
3. Early involvement of traffic and constructability experts in design phases.
4. Enhanced design review processes with multiple disciplinary checks.

Lessons Learned

• Design validation must incorporate up-to-date standards and practical use considerations.
• 3D modeling tools are essential for detecting spatial conflicts.
• Multidisciplinary collaboration improves design accuracy and constructability.
• Thorough review processes prevent costly rework and delays.

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

• Are designs checked against the latest standards and real-world conditions?
• Are advanced modeling and clash detection tools used?
• Are traffic engineers involved early in the design process?
• Is the design review process comprehensive and multidisciplinary?