TUNNEL OPERATIONS & MAINTENANCE Tunnel O&M - Estimating Approach
The Stitch’s proposed deck over the Downtown Connector creates a road tunnel requiring special elements and mechanical and electrical systems to support safe traffic operation. As such, the project team developed order of magnitude cost estimates to operate and maintain these systems. The following five key O&M cost components associated with these types of road tunnel operating systems were identified: (1) dedicated operations staff, (2) required inspections, (3) routine maintenance, (4) anticipated repairs and upgrades, and (5) annual electrical power costs. Cost escalations were not included in these estimates. The project team then developed the O&M costs for the three different operational periods that align with the Stitch’s phased development approach: • The Near-term – This considers the period in which the first phase of the Stitch would be in construction and no permanent road tunnel systems are yet in operation. As such, no tunnel O&M costs are assumed for this period. • The Mid-term – This period assumes the Stitch’s first phase road tunnel is complete and operational. Tunnel O&M costs for this period were estimated for a road tunnel of approximately 900 feet in length. • The Long-term – This period assumes all three of the Stitch phases to be complete and operational. Tunnel O&M costs for this period were estimated for a road tunnel of approximately 2,900 feet in length. Specific tunnel infrastructure and system operational requirements are not yet defined since the road tunnel concept design is not yet developed. These requirements will be more fully determined during the concept development and design stage of the Stitch. Therefore, to establish the order of magnitude O&M costs presented herein, the following key assumptions have been made: • For the road tunnel, each phase of the Stitch will be required to comply with NFPA 502 Standard for Road Tunnels, Bridges, and Other Limited Access Highways. • The road tunnel facility inspections will be required to comply with the Federal Highway Administration’s National Tunnel Inspection Standard
• The transport of hazardous cargo will be restricted from this tunnel.
• The following tunnel operating systems and elements will be required for both the Mid-term and Long-term Phases:
Normal and Emergency Power
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Tunnel Roadway Lighting
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o Supervisory Control and Data Acquisition
Traffic Control and Monitoring
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