Is the maintenance cost of a shield machine higher than that of a tunnel boring machine? The maintenance cost of a shield machine is indeed generally higher than that of a tunnel boring machine, mainly due to the following reasons:

  1. Complexity: The structure of a shield machine is more complex, containing multiple subsystems, such as cutting system, propulsion system, sealing system, installation system, etc., each of which requires regular inspection and maintenance.

  2. Maintenance frequency: Since shield machines work continuously for a long time in harsh underground environments, their wear and failure rates are relatively high, which means that more frequent maintenance and replacement of parts are required.

   3. Maintenance cost: The maintenance cost of a shield machine includes not only regular maintenance costs, but also the maintenance and replacement of advanced components such as cutting heads, which are often very expensive.

  4. Professionals: The maintenance of a shield machine requires professional technicians who have the corresponding knowledge and skills to deal with complex maintenance issues, and the training and employment costs of these professionals are also high.

  5. Downtime: When a TBM fails, it may take a long time to repair, during which time normal construction activities cannot be carried out, resulting in potential economic losses.

   6. Spare parts inventory: The key spare parts of the TBM need to be kept in sufficient inventory to cope with sudden maintenance needs, which also increases maintenance costs.

   7. Depreciation cost: The purchase cost of the TBM itself is higher than that of the TBM, and coupled with the higher maintenance cost, its overall depreciation cost is also relatively high.

   Therefore, the maintenance cost of the TBM is high, which needs to be fully considered in the project budget and long-term operation plan.