Enhancing Success in NATM Tunnel Construction: Realistic Planning, Real-Time Monitoring, and L4 Scheduling

Introduction:

NATM (New Austrian Tunnelling Method) tunnel construction projects are often driven by the need and strict time constraints under varying geology, prevalent restriction of space and feasibility. This article explores the challenges faced by technical experts, designers, and planners in meeting these demands. It also highlights the importance of considering a range of factors during the bidding and procurement processes to ensure successful project execution. Additionally, we discuss mitigation strategies that can be employed to optimize efficiency and reduce risks in NATM tunnel construction.

Challenges in NATM Tunnel Construction Projects

Pressure to Minimize Construction Time for ROI

Time Constraints in Non-Strategic Projects

In non-strategic projects funded by investors or financial institutions, minimizing construction time is paramount to achieve ROI. Promoters, developing agencies, and owners are under immense pressure to expedite the project's completion during the preliminary phase, such as the Project Feasibility Report (PFR). Technical experts and designers subsequently inherit this time constraint, making it challenging to comprehensively address all project aspects. The fear of losing the consultancy job further intensifies the pressure on PFR consultants to comply with the established rules without question.

Influence of External Factors on Strategic Projects

Even strategic projects are not immune to external factors, including geopolitical, international, domestic, and economic conditions. These exigencies significantly impact project requirements and objectives. While the report is submitted, it is crucial to acknowledge the potential influence of these multidimensional factors and adapt accordingly during the planning and design phases.

Overlooking Factors during Procurement Process

Limited Bid Preparation Time

The procurement process plays a vital role in selecting the contractor for the project. Contractors must adhere to the timeline defined in the Instruction to Bidders (ITB) or customer requirements to remain competitive. Failing to meet the timeline may result in disqualification and forfeiture of the bid security. Unfortunately, several factors are often overlooked during the procurement process due to limited bid preparation time and reliance on past experiences. This can lead to inadequate consideration of potential problems and unaccounted-for factors.

Neglecting Confined Space Constraints

Lack of deep understanding regarding work methods and constraints in confined spaces is a common issue. Factors such as the necessity of niches, construction time for niches, cushion of unsupported length, and sequence of parallel niche activities are frequently overlooked. In some cases, due to financial constraints or ambitious turnover targets, critical activities like niche maintenance and drainage are neglected over a significant length. This affects the construction cycle time and can lead to delays. Furthermore, if niche activities are required at a later stage, it can disrupt ventilation and further delay the project.

Inadequate Preparation for Uncertainties

Oversimplification of Ground Consolidation and Grouting Sequences

Underground space is inherently uncertain, and this uncertainty is often overlooked or inadequately addressed. Spreadsheet-based calculations may oversimplify activities like ground consolidation, grouting sequences, and probing. When these activities become necessary, delays can extend for weeks or even months. Proper preparation and arrangements for such uncertainties are crucial to avoid significant project setbacks.

Lack of Coordination between Execution and Planning/Design Teams

Challenges with Designers and Planners

Unrealistic planning frequently arises from a lack of coordination and understanding between execution teams and planning/design teams. This issue is compounded by a fundamental lack of domain execution experience among designers and planners, as well as a limited working knowledge of design and project management software within the execution team. Consequently, the execution team encounters practical constraints and deficiencies on numerous occasions, exacerbating delays, while the planning team struggles to provide effective support. To ensure successful execution within the designated time limit, improved coordination, daily updates to project schedules, and proactive resource management resulting from the consequences of earlier activities are essential.

Strategies for Efficient NATM Tunnel Construction

Detailed Scheduling during Feasibility Studies and DPR

Utilizing Ample Time for Comprehensive Schedules

To mitigate these challenges and enhance efficiency in NATM tunnel construction, the following strategies may be beneficial:

Utilization of the ample time available during feasibility studies, Detailed Project Reports (DPR), investigations, and bid preparation to develop comprehensive schedules in parallel.

Consolidating Drawings, Calculations, Models, and Timelines with BIM

Embrace digitization and Building Information Modelling (BIM) to consolidate drawings, calculations, models, and timelines in a unified format. This enables easy visualization and empowers contractors to optimize their bids and consider associated risks.

Assisting Contractors with Digitized Information

Replacing Lengthy Tenders with Digitized Information

Assisting Contractors with Digitized Information: Instead of relying on traditional lengthy tenders, provide contractors with digitized information, enabling them to better understand the project and allocate bidding time towards optimizing their proposals. This approach promotes fair estimation, competitive bidding, and reduces bidding time.

Promoting Fair Estimation and Competitive Bidding

Efficient and successful NATM tunnel construction requires a comprehensive understanding of project constraints, adequate planning, and effective coordination between design and execution teams. By proactively addressing challenges, embracing digitization, and implementing mitigation strategies, project stakeholders can optimize construction timelines, reduce risks, and achieve better outcomes in NATM tunnel projects.

Realistic Planning and Real-Time Monitoring

Thorough Assessment of Project Requirements and Risks

Realistic planning involves a thorough assessment of project requirements, constraints, and risks during the PFR stage. It considers factors such as geotechnical conditions, resource availability, and project objectives to develop a feasible and achievable construction plan. Realistic planning helps set clear expectations, identifies potential challenges, and enables stakeholders to make informed decisions to optimize project outcomes.

Continuous Tracking and Analysis of Project Progress

Real-Time Monitoring: Real-time monitoring involves the continuous tracking and analysis of project progress and performance during construction. It provides timely updates on key parameters such as schedule adherence, resource utilization, and quality control. Real-time monitoring allows project teams to identify deviations from the plan, take corrective actions promptly, and mitigate potential delays or issues. It enables proactive decision-making, reduces the likelihood of surprises, and improves overall project management.

Implementation of L4 Scheduling during PFR Stage

Granular Representation of Construction Sequence

The L4 schedule refers to a detailed and granular project schedule that breaks down activities into smaller components and includes specific timelines, resource requirements, and interdependencies. Implementing an L4 schedule during the PFR stage provides a more accurate representation of the project's construction sequence and allows for better planning and optimization. It helps identify critical paths, enables efficient resource allocation, and facilitates the identification of potential bottlenecks, risks, or conflicts in advance. The L4 schedule improves coordination among various project stakeholders, enhances communication, and assists in making informed decisions to meet project timelines effectively.

Efficient Resource Allocation and Identification of Critical Paths

By incorporating realistic planning, real-time monitoring, and implementing an L4 schedule during the PFR stage, project teams can experience several benefits, including improved project control, reduced risks, enhanced decision-making, and better overall project outcomes. These practices ensure that the project remains on track, avoiding costly delays and enabling stakeholders to meet their ROI objectives while maintaining high-quality standards.

Furthermore, these practices eliminate the possibility of overlooking potential risks and conflicts. By tracking the preparation and subsidiary procurement of resources, project teams can ensure that all necessary elements are accounted for and effectively managed.

Another significant advantage is the reduction of disputes related to delays, extended stays, and claims. By tracking all micro events and their consequential effects, these practices provide a clear record and enable proactive management, minimizing the likelihood of disputes arising.

Overall, by implementing realistic planning, real-time monitoring, and an L4 schedule, project teams can optimize project performance, minimize risks and conflicts, and achieve successful project outcomes.

Conclusion:

Efficient and successful NATM tunnel construction necessitates a comprehensive understanding of project constraints, realistic planning, and effective coordination between design and execution teams. By proactively addressing challenges and implementing the recommended strategies, project stakeholders can optimize construction timelines, reduce risks, and achieve better outcomes in NATM tunnel projects. Realistic planning, real-time monitoring, and the implementation of L4 scheduling during the PFR stage provide a solid foundation for success. These practices ensure that the project stays on track, avoids costly delays, and enables stakeholders to meet their ROI objectives while maintaining high-quality standards. In the world of NATM tunnel construction, these strategies pave the way for enhanced project control, reduced risks, and better overall project outcomes.