Technology Shaping Tunnel Rehabilitation

Twenty-five roadway tunnels are integral to allow for travel in geologically isolated portions of the Rocky Mountains throughout the state of Colorado. Every 24 months, each of these tunnels, according to Federal Highway Administration (FHWA) National Tunnel Inspection guidelines, are inspected by a team of engineers and geologists that report defects in the tunnel’s critical systems that include Structural, Civil, Mechanical, Electrical, and Fire/Life Safety elements. These inspections help the Colorado Department of Transportation (CDOT) to manage their tunnel infrastructure assets by improving the life cycles and safety for upcoming fiscal years. This paper illustrates that inspections can locate critical defects affecting the strength of the unlined tunnels. The inspection and following rehabilitation of the tunnel is discussed in this paper. The use of a handheld LiDAR scanner during this inspection significantly decreased the time and budget required to evaluate and rehabilitate the existing unlined rock tunnel and allowed the design team to maintain traffic clearance.