Case Study: Subcontractor Safety Violations Delay Tunnel Excavation in Colorado (2020)

Project Overview
• Name: Denver Transit Tunnel Project
• Location: Denver, Colorado
• Year: 2020
• Project Size: $400 million
• Scope: Urban transit tunnel excavation and lining
• Lead Agencies/Contractors: Colorado DOT /

Category of the Issue, Problem, or Challenge
• Subcontractor Management
• Safety Compliance

Summary of the Issue, Problem, or Challenge
The excavation subcontractor failed multiple safety audits, resulting in work stoppages and a 3-week delay due to required corrective actions.

Root Cause Analysis

• Insufficient safety training and supervision on subcontractor crews.
• Poor hazard identification and mitigation practices.
• Inadequate communication of safety policies and enforcement.
• Lack of prime contractor involvement in safety monitoring.

Impacts Due to the Issue, Problem, or Challenge

• Temporary halt in tunnel excavation activities.
• Additional costs for safety program remediation and training.
• Increased scrutiny from regulatory agencies.

Corrective Actions Taken

1. Implemented comprehensive safety training programs.
2. Increased onsite safety supervision and audits.
3. Enhanced hazard communication and reporting mechanisms.
4. Integrated subcontractor safety performance into prime contractor evaluations.

Lessons Learned

• Safety compliance is essential to maintain schedule and avoid penalties.
• Continuous training and supervision reduce safety violations.
• Collaborative safety culture improves overall project performance.

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

• Are subcontractor safety programs adequate and enforced?
• Is there sufficient onsite supervision and auditing?
• Is safety performance linked to subcontractor accountability?