Inspection and maintenance procedures for tunnels and underground structures are valuable tools, which help preserve the design life and keep these structures at a safe and operational level.

As with above grade facilities, inspection and maintenance should begin at the transition from construction closeout to operations.  Knowledge of the design, environment and construction materials is essential for the evaluation of the overall structure.

Inspection procedures should first establish an initial inventory/condition, which will serve as baseline for future inspections. The inspections should cover the following categories: Structural elements, mechanical systems, electrical systems, and other systems appurtenances.  Ideally all data collected during the initial and follow-up inspections should be gathered in an electronic database and offer a presentable graphic interpretation.

Maintenance remains the key in preserving the operational status of all underground structures.  Not only deficiencies discovered during the inspections must be addressed and corrected but also all ventilation, fire, life & safety and drainage installations shall be tested and kept operable at all times.

Inspection and Maintenance Projects:

Dallas Area Rapid Transit (DART), Shotcrete Mapping Methods for DART’s Shotcrete Lined Tunnels, November 2003
Virginia Department of Transportation (VDOT), Midtown Tunnel Inspection, September 2003
Dallas Area Rapid Transit (DART), Tunnel Inspection Report, October 2002
Dallas Area Rapid Transit (DART), Tunnel Drainage System Video Inspection Report, May 2002
Washington Metropolitan Area Transit Authority (WMATA), Tunnel Inspection & Rehabilitation Concept, May 2002
Dallas Area Rapid Transit (DART), Tunnel Drainage System Cleaning, June 2001
Dallas Area Rapid Transit (DART), Tunnel Inspection Report, May 2000