Tunnel Business Magazine

AUG 2017

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addition, the GBR should represent a "reasonable interpreta- tion" of the subsurface information assembled for the project that is compatible with and supportive of the plans and speci- fications included in the contract. Such is the overriding goal of a "good" GBR. However, and this is a big however, that is not always the case as sometimes the contract contains a "bad" GBR! By defini- tion a bad GBR represents one last, mistaken attempt by the Owner and it Designers to shed liability onto the Contractor by establishing extremely conservative and unreasonable "interpretations" and "baselines" for the work. Sometimes an Owner believes that by grossly exaggerating the information uncovered during the subsurface investigation he can create a wall of liability protection that will somehow "insulate" the Owner from a DSC claim. Unfortunately, and more often than not, this plan will backfire. For instance, it is highly likely that experienced tunneling contractors will realize what is happen- ing and 1) come to the realization that the Owner is not serious about working together, and 2) begin to carry large contingen- cies in its bid to cover the liability implications of a bad GBR. Even worse, if things do not work out in the field as the Owner anticipated, experienced tunneling Contractors can be both highly imaginative and highly aggressive in pursuing various claims against the Owner almost no matter what is written in the contract. In general, and based on experience, a majority of claim resolutions by DRBs and by the courts have been some- what sympathetic to the Contractor based on a realization of how truly difficult it is to bid a tunneling project and to accom- plish all of the hard work and complex logistical requirements needed to build a tunnel in a proper manner. Hence, a "good" GBR is a thing of beauty and will legitimate- ly contribute to the successful outcome of a tunneling project. A "bad" GBR does not. In fact, a bad GBR is less than worthless because it actually contributes to the creation of an adversarial relationship that is so highly detrimental to a successful proj- ect. In conclusion, the concept of a good GBR, as defined by the ASCE Guidelines, is a positive part of a tunneling contract while a bad GBR is not. – The last topic that needs to be discussed as part of Intelligent Tunnel Design© is construction monitoring. It is absolutely imperative that the tunnel Owner assign experienced tunneling professionals to observe and document every aspect of construction activity taking place in the field. In general, these activities consist of observing ground conditions and ground behaviors, documenting con- struction means and methods, and monitoring the behavior of overlying and adjacent third parties. Good construction monitoring is one more important part of Intelligent Tunnel Design©. Accurate project records are essential to making sure that the work is being performed in accordance with contract requirements and that the ground conditions and ground behaviors are compatible with the geo- technical documents. If trouble does develop, then both the Owner and the Contractor must have in their possession ac- curate and complete project records that can be used to help re- solve alleged claims either in the field, as a result of alternative dispute resolution (i.e., a Dispute Review Board), or, if all else fails, as a result of litigation. It is the height of false economy for the Owner of a tunnel project to believe that a tunnel can be constructed without adequate professional observation and assistance in the field. Given below is a flow chart that summarizes all of the top- ics discussed above and serves as the basis for Intelligent Tun- nel Design©. Using the above flow chart in a manner as described in this paper is the best way to pave the way for a successful tunnel- ing project. In summary, and as shown in the chart Intelligent Tunnel Design© consists of the following: Project Layout – Create the space that is needed both for construction and for the final facility. Subsurface Investigation – Perform a comprehensive sub- surface investigation and prepare an accurate GDR and a "Good" GBR. Ground Behavior vs. Ground Control – Do a good job of brainstorming all of the design requirements and construction procedures needed to build the subsurface space in the exist- ing ground condition. Project Design – Establish all of the design criteria needed both to create a safe and stable underground opening and to provide a highly satisfactory finished facility. Construction Methods – Specify only those construction methods that are necessary to construct the temporary facili- ties in a safe and stable manner. Third P e certain that proposed design criteria and construction methods are sufficient to safeguard existing overlying and adjacent third parties. Contract Document – Assemble a contract document that is specifically tailored to tunnel construction and which ad- equately describes everything that needs to be performed by the Contractor in order to accomplish the above design and construction requirements. Project Procurement – Create a positive and cooperative environment for the successful completion of your tunneling project. Construction Monitoring – Assign highly experienced tun- neling professionals to monitor and record all aspects of con - struction activities. If you actually do all of the activities listed above as part of your plan for Intelligent Tunnel Design©, then there is every reason to believe that you can and will achieve a successful tunneling project. TUNNELINGONLINE.COM TBM: TUNNEL BUSINESS MAGAZINE // AUGUST 2017 F E A T U R E S T O R Y 30 Dr. Gary S. Brierley is President of Doctor Mole, Inc. Dr. Arthur J. McGinn is President, Brierley Associates Corporation.

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