Indecent Haste that Ignored Tunnel Project’s Viability Within a Risk-based Framework

For a technically challenging project, the proposed tunnel has not been through the required public selection processes for consultants and bidders, environmental studies, public hearings, design completion and independent reviews. It does not have a detailed, bottom-up cost estimate. It does not even spell out the number of lanes it going to build. If this is not a rush job, why has the state government opted for a short cut to bulldoze through the award of letter of intent? 

Underground construction presents unique risks that are not typically encountered on other types of heavy civil construction. It is industry practice to evaluate any tunnel project’s viability within a risk-based framework. This has not been done for the tunnel and it is not accounted for in the tendering process.

Until today there is no effort to carry out additional subsurface exploration and testing or revisit designs, construction sequences, and associated costs and schedules to mitigate the risks reflected in the anticipated subsurface conditions, and identify other elements including agency, owner/operator or local requirements, which could cause major scope increases during final design or construction.

Without preliminary engineering study, there is insufficient info to complete a level of tunnel design that can be used to conclude the selection of a tunnel boring machine (TBM) and arrive at a credible estimate of the TBM advance rate. One of the largest cost factors associated with tunnel construction is determining what kinds of geological conditions exist between the portals or shafts of a tunnel. Modern geotechnical engineers utilize a variety of imaging technologies and boring samples to determine rock type and groundwater penetration. These technologies can provide an acceptable level of confidence in the type of rock that needs to be bored through. The major geological and geotechnical factors that pose a high level of uncertainty to the current design and estimates of schedule and cost are totally ignored by Lim Guan Eng administration throughout the tendering process.

The developer is obligated to provide safety equipment and high levels of insurance. For example of a construction safety cost which must be considered is proper ventilation, which is necessary to provide for the health of workers during construction. These costs can be very high which often results in construction management companies making the bare minimum investment in safety required. 

Since there is no preliminary engineering study, no normal operations ventilation analysis has been performed. This would normally be expected in order to give confidence in the sizing of ventilation system components, particularly the ventilation shafts. In the absence of this analysis, ventilation shaft sizes remain unconfirmed. An increase in shaft size will have significant cost implications. 

Additionally, there are costs associated with providing for the safety of people using a tunnel after construction. All transportation tunnels will require more portals and ventilation shafts than may be necessary during the construction phase. One of the largest safety costs is associated with preventing and suppressing tunnel fires. Protecting against fire involves detection and communication systems to determine the source of a fire. Tunnel fires and smoke can spread rapidly, which necessitates fire suppression and ventilation systems. In addition, there is a need for a means of egress and regular intervals to allow for the swift exit of individuals using the tunnel in question.

Lastly, there is a cost associated with protecting structural elements from fire so that the tunnel will not immediately collapse in the event of a fire. 

There have been cases of unexpected water penetration which have drastically increased the price of tunnelling and severely reduced the profit for the contractor. One such case was during the construction of the Burnley tunnel, part of Melbourne’s CityLink project. The Burnley tunnel passes deep beneath the Yarra River, and consequentially resulted in having a very high water pressure surrounding the tunnel. As a result of unforeseen condition in the design stage, some of the 1.8m thick concrete floor panels or inverts were lifted out of place by the water pressure, causing the contractor to lose $154m in damages (Samuel, 2007). Problems like the Burnley tunnel cause contractors to place higher percentage contingencies into the bid price than any other infrastructure projects. This variance in the type of substrate present in different countries has a profound effect on the cost of tunnelling.

In the case of cost overrun, what should we do? Abandon the project? Bailout the developer at our expenses? Allow the developer to build sub-standard tunnel and ignore safety requirement in order to prevent cost overrun? Lim Guan Eng need to clarify how he going to handling issues of cost overrun and safety if he insists that the tunnel project should proceed as planned.