Risk Management for Tunnels

All tunnel projects face unknowns and uncertainties during planning, design, construction, and/or operation. With tunnels playing an ever-increasing role in a community’s infrastructure mix, it’s important to understand how to mitigate the risk of these inherently complex undertakings. A proactive risk management process, implemented as early as possible in the process, can significantly reduce negative outcomes, and increase the chances of success.

What is Risk Management? Risk management generally means recognition, evaluation, and prioritization of risks followed by the economical application of resources to minimize, monitor, and control the likelihood and impact of unfortunate events. This is typically done through four strategies: avoid, transfer, mitigate, or accept.

Examples of risk management activities that may be used for tunnels and underground projects include establishing a risk policy and risk acceptance criteria, a risk assessment of the project, detailed analysis of areas of special interest or concern, contract evaluation, determination of risk clauses in the contract, design/construction risk assessments, and many others.

Risk Planning and Identification: To form a common reference point for all parties involved (e.g., the owner, designers, insurers, and contractors), the owner establishes a project risk policy. The risk policy outlines how risks will be addressed and managed by the project team. This also includes the identification of risks, which is an essential task early in a project.

For most tunneling projects, the scope includes: a) Risk to the health and safety of workers and third parties, including personal injury and, in the extreme, loss of life. b) Risk to property, specifically existing buildings and structures, cultural heritage buildings, and above and below ground infrastructure. c) Risks to the environment, including possible land, water, or air pollution and damage to flora and fauna. d) Risk to the owner in delay of completion, causing financial losses and additional unplanned costs.

Certain risks may be transferred, either contractually or through insurance, others may be eliminated, mitigated, or accepted.

Risk Analysis: Next is the analysis to determine the likelihood and impact of each identified risk. One effective tool is a Probability and Impact Matrix. It uses the combination of probability and impact of occurrence for each risk. This helps to determine those risks that need more attention and/or detailed response plans.

During the early design stage, a qualitative risk assessment will be carried out focused on the identification of potential hazards expected to be included in the project. The main purpose is to raise the awareness of all concerned to the major risks and provide a structured basis for the mitigating decisions to be taken.

When a contractor has been chosen, further discussions with the owner and designer may lead to a more quantitative risk assessment and sensitivity analysis. This will be based on the intentions of the owner and suggested procedures of the contractor.

Risk Planning: After risks have been identified and analyzed, it’s time to develop a plan. This includes determining how the project team will avoid, transfer, mitigate, or accept each risk. It’s important to make sure each risk is covered by an appropriate mitigating response, as well as assigned to the individual/project team member best equipped to address it.

Risk Monitoring: As the project progresses, the risks identified need to be monitored to determine the effectiveness of your risk management plan.

Some items to consider include: Has the risk been mitigated? Has the priority of the risk changed? Will the risk impact additional stakeholders? Is the individual assigned to manage the risk still the best choice?

Considerations for Construction of

Tunnels and underground projects involve significant uncertainties as it is not possible to know exactly what conditions will be encountered during mining, and how the materials will behave when excavated. At this stage, risk transfer options are minimal. The best strategy is to reduce the severity of as many risks as possible in the early stages of planning and conceptual design.

Thankfully, there are tools for better understanding site conditions and reducing risks during construction. The results of a subsurface investigation are typically reported in a Geotechnical Data Report (GDR), which describes the ground properties and presents boring logs and laboratory test data. A Geotechnical Baseline Report (GBR) provides an interpretation of these results as a bidding baseline. However, most GBRs are not 100% accurate, and actual site conditions will be different (to some extent) from the technical parameters used as a baseline.

To assist in the resolution of disputes between the owner and contractor, such as Differing Site Conditions, an owner can include in the contract the establishment of a Dispute Resolution Board (DRB). The intent of the DRB is to consider the disputes fairly and objectively, and provide recommendations for resolution that benefit both parties.

In Summary

Even the best risk managements systems and procedures alone are not enough. A commitment by each member of the team to developing and consistently implementing high quality mitigating actions is the key to a successful project.