Case Study: Subcontractor Electrical Installation Errors Lead to Rework on Seattle Bridge Project (2021)

Project Overview
• Name: SR 520 Bridge Replacement
• Location: Seattle, Washington
• Year: 2021
• Project Size: $1.5 billion
• Scope: Bridge replacement including complex electrical and lighting systems
• Lead Agencies/Contractors: Washington State DOT /

Category of the Issue, Problem, or Challenge
• Subcontractor Management
• Quality Control & Technical Execution

Summary of the Issue, Problem, or Challenge
Electrical subcontractor made design interpretation errors during installation, resulting in system malfunctions and significant rework.

Root Cause Analysis

• Subcontractor’s engineering staff had insufficient bridge-specific systems experience.
• Poor communication and coordination between subcontractor design and field teams.
• Inadequate quality control inspections and testing prior to handover.
• Lack of prime contractor verification of subcontractor’s technical submittals.

Impacts Due to the Issue, Problem, or Challenge

• Electrical system rework caused 2-month delay.
• Increased costs for labor, materials, and extended equipment rentals.
• Risk of compromising bridge safety and functionality.

Corrective Actions Taken

1. Subcontractor hired specialized engineers with relevant bridge experience.
2. Improved coordination protocols between design and field personnel.
3. Increased frequency and rigor of QC inspections and pre-commissioning tests.
4. Prime contractor enhanced review and approval process for technical submittals.

Lessons Learned

• Subcontractors must have experienced personnel for specialized systems.
• Coordination between design and construction teams prevents errors.
• Early and thorough QC inspections catch issues before costly rework.

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

• Does the subcontractor have specialized technical expertise?
• Are design and field teams coordinated with clear communication channels?
• Are QC inspections comprehensive and timely?