Manageable Complexity – BIM and Risk-Based Construction Controlling in Tunnelling

Credit/Quelle: Salzmann

1 | BIM- and risk-based controlling effectively reduces the risks in tunnelling, improves cost transparency and thus ensures the yield target of the overall construction works

Credit/Quelle: Salzmann

Credit/Quelle: Vose Software

2 | Distribution function, planned position (most likely; mode), 50:50 (median) and average (mean). The most likely scenario (red line) in this example estimates 15 days of construction time. The probability distribution however also shows that construction time could extend to 35 days under certain circumstances

Credit/Quelle: Vose Software

Credit/Quelle: Salzmann/Faro

3 | Left: planned cross-section of a tunnel cross passage; right: cross passage in the construction phase. Point cloud images document the current state, which is compared with planned state through a model check

Credit/Quelle: Salzmann/Faro

Credit/Quelle: Salzmann

4 | Risk-based construction variations cause numerous changes of plan in the entire construction process. Tunnel drive (left), construction of cross passages (middle) and removal of excavated material (right) etc.

Credit/Quelle: Salzmann

Credit/Quelle: Salzmann/Vose

5 | List of construction items with completion rate, expected value of the costs (likeliest) and risks and insecurity. In a model iteration, values (distribution) are gathered under the triangular function and displayed as a bar chart

Credit/Quelle: Salzmann/Vose

6 | Total costs bar chart: the probability of budget overrun lies in this example with about 117 million at 5 %; the construction budget lies with a 95 per cent probability under 133 million

Credit/Quelle: Salzmann/Vose

7 | The tornado diagram shows what risks and insecurities of individual bill items have the largest influence on the cost budget (in millions of dollars) and structures these in a hierarchy

Credit/Quelle: Salzmann/Vose

Credit/Quelle: Amberg Technologies

8 | Quality assurance by scanning the top heading vault with a Faro laser surveying instrument: the scan data is analysed in “Amberg Tunnel” and the planning of measures is derived from this

Credit/Quelle: Amberg Technologies

Credit/Quelle: Salzmann/Faro

9 | The laser scan documents dynamic changes to construction components. Their effects on time, costs and construction state are
reported to the client organisation

Credit/Quelle: Salzmann/Faro

Four out of five major projects are not completed within the planned time and the budgeted costs. The reasons for this great uncertainty lie in the lack of integration of a quantitative risk analysis (QRA) and the duty of documentation laid down in BIM. Although the BIM standards specify this, both risks and the chances arising in the course of construction are seldom documented. This leads to incorrect estimates and ad-hoc assumptions cumulating over the construction period. One solution is to integrate the BIM duty of documentation and the QRA into risk-based construction controlling. The rapidly developing BIM processes using laser scan technology can also help to improve construction documentation and the controlling of costs, time and progress. The effects of the described procedure in BIM and risk-based construction controlling effectively reduce risks, improve cost transparency and thus ensure the intended return of the overall project.

Complexity in Tunnelling

In modern tunnelling, numerous requirements are imposed in the phases of design, construction and operation. From the start, it is necessary to harmonise the premises of site management, coordination and technology due to the complexity of tasks and organisation
(Fig. 1).

The client wants to implement the project within the projected cost and time framework and provide for high standards of quality and safety. Construction companies on their side have to keep costs low and bear numerous geological and construction risks. On many major tunnel projects, harmonising these...