By Don Del Nero
The engineering community has historically followed the truism that means and methods of construction are in the realm of the builder on a design-bid-build project. In the realm of the tunnel industry though, this truism does not apply explicitly. In a competitive environment where low bid often prevails, a tunnel contractor is obligated to make optimistic assumptions and attempt to implement on-hand or idle equipment in order to win work and stay in business. This is not intended as an incendiary comment, but part of the inherent nature of being a savvy contractor.
On the other hand, an owner is obligated, especially without contractor pre-qualification, to set limits on means and methods or even specify specific machine attributes or technologies that are not appropriate in order to ensure the best equipment is employed. This trend has become much more prominent in the last 10 to 15 years and is based on the premise that an owner “owns” the ground and the simple fact that a consulting engineer generally studies ground conditions for a year or two. If this is compared to the typical bid period of four to eight weeks, the tunnel contractor has a very limited amount of time to study ground conditions compared to the engineering phase.
This creates a certain risk element that is imputed to an underground project. As such, the means and methods arena, historically only the domain of the construction industry, has been blurred by the shear risky nature of the underground business. A dilemma is thus created for designers and contractors and with most general conditions written for performance-based specifications published by many agencies.
Means & Methods and Specifications
David Hatem (1998) describes the means and methods of construction as, “the means and methods, sequences, techniques, and procedures of construction, as well as any associated safety precautions and programs, and all incidental or temporary devices required to construction the project.” Traditionally, means and methods of construction have been the sole domain and exclusive responsibility of the construction contractor primarily because the contractor was viewed as the party best suited to decide what works and what does not work in the construction of the intended facilities and the most experienced in determining and designing what temporary facilities are required to construct the end-product. Hatem (1998) puts it this way, “The Contractor has the skill and experience to devise the means and methods of construction; he or she is in control of the construction work, and his or her competence in performing that role provides the contractor with the best prospect to control the risks of construction and the opportunity to win bids and reap profits.”
In many respects, this is an inalienable truth. Readers on the consulting side can testify to the old truism and aversion to the specifying of means and methods in tender documents. Early in the construction industry it was taboo to even think of specifying the type of support for an excavation or directing the contractor on the actual equipment to be used for excavation. Yet, the issue of means and methods being specified in tender documents has gone through profound changes over recent decades in the underground industry including engineers taking significant responsibility, intended or unintended, for them. The root of this trend has been construction cost escalation far beyond inflation and claims and disputes.
What is so unique about the underground industry that has fostered changes in how means and methods are addressed is that, based on the author’s experience, somewhere between 2/3 to 3/4 of construction cost is in the means and methods employed just to create the underground space. What that means is that the final facilities ultimately placed into service only play a small role in the monetary value of an underground project. As such, there is a heightened awareness that the means and methods in many cases are where the project is won or lost from the standpoint of fiscal success and constructability. With so much riding on implementing optimal means and methods it has become common practice for engineers to enter into this traditional domain of a construction contractor during the design phase. It really boils down to who has the best recipe!
A synopsis of both “recipes” as applied to tunnel boring machine design is provided by Reilly (1997).
“The prescriptive approach fully defines the type and characteristics of the tunnel boring machine and the sequence of tunneling and ground support operations.”
“The performance approach requires only that the contractor meet key project performance requirements and leaves substantial freedom of choice to the contractor, regarding machine types, methods and sequence of operations – so long as he meets his contractual requirements.”
Having two different recipes raises many difficult questions for the underground construction community including, but definitely not limited to, 1) is it possible to be too prescriptive in a prescriptive specification; 2) to what extent is the “low-bid” competitive environment responsible for the trend toward more engineer-specified means and methods; 3) to what extent do more prescriptive specifications tend to increase bid prices and final project costs including the cost of change orders and differing site condition claims; 4) to what extent does an engineer’s means and methods design discourage contractor innovation; 5) to what extent does an engineer’s means and methods design dull a contractor’s competitive edge; and 6) to what extent does the owner/engineer team “own” the means and methods specified?
Giving definitive and indisputable answers to these questions is challenging, if not impossible, because the answers tend to be a mix of project experience (bad experience to be more exact), orientation of the party answering the question, construction philosophy, ground conditions in question, conditions of the contract, and administrative law. This dilemma, and one can argue controversy, has far reaching implications and one that impacts all parties to the construction phase.
One of the ways the underground community has dealt with this issue is to “get married!” As such, many projects now use some form of early contractor involvement, or at a minimum, using specifications that are a blend between prescriptive and performance specifications. That being the case, maybe the question is not really whether to use prescriptive vs. performance but how much is too prescriptive? This is still a difficult question for a definitive and unchallenged answer. An abbreviated position statement for each approach is provided by Reilly (1997).
“The basis for the prescriptive approach is that the owner, advised by tunneling, geotechnical, and other experts, has the time, knowledge and ability to determine the best machine type, machine characteristics, methods and sequence of operations project requirements.”
“The basis for the performance approach is that the contractor, with his experience, is best able to determine the most appropriate methods and techniques, using practices that best suit his equipment and experience. This should result in a bid that represents the best price for the underground work.”
These points provide poignant perspectives for each approach, but there are numerous other viewpoints. Highlighting many of the other parallel considerations in this dilemma may shed some more light and help define a direction forward on the subject.
Bases against Engineer-derived Means and Methods
There are situations where it is fairly clear that engineer-derived means and methods pose potential risks to a project or that simple precaution by an owner greatly reduces the need for engineer’s overindulgence in means and methods. Some of these are highlighted below.
- If pre-qualification of tunnel contractors is used, the owner has some assurance that the best means and methods will be implemented so there is far less need for engineer-derived means and methods;
- Keeping means and methods in the contractor’s domain promotes contractor innovation – they have an incentive to innovate;
- Excavation support is often linked with the equipment and means and methods being used so it can’t reasonably be fully prescribed and forecasted by an engineer;
- A well accepted motto for risk management is to assign risk to the party best able to control the risk. Who better to control ground risk than the contractor who is the party actually mining the ground? The reason the answer is no one to this question, is that contractors can use the observational method to monitor ground conditions and behavior and readily adjust to a pre-engineered Plan B if Plan A is not working;
- Mechanized tunneling methods have become more and more sophisticated and therefore the selection and design of these systems should be conducted by the equipment manufacturer and the tunnel contractor who actually has to operate the equipment;
- Engineers simply do not have the depth of experience in actual operation of construction mining equipment;
- The owner typically forces a strict contract with limited scope, LOE and budget. This provides a disincentive for the engineer to spend effort to think outside the box (more work) or be innovative. When engineers on a lean budget are asked to include prescriptive requirements to help level the playing field and hopefully reduce owner’s risk (of DSC claims), such engineers may not have the budget to fully investigate options, evaluate risks and develop the most effective prescriptive specs. The result may be either more-costly-than-necessary specifications or defective specifications;
- Construction constraints associated with noise, vibration, ground and structure settlement, muck disposal, dewatering, and staging are so intrinsically connected to the construction phase that an engineer can’t possibly consider the impact to all these factors if the engineer defines the means and methods of construction;
- In a survey depicted in Tirolo & Almeraris (2005), only 15 percent of heavy construction contractors believe the introduction of suggested methods of construction in the contract documents actually improved constructability;
- An engineer’s specified method is an implied warranty and if it fails, the owner pays for the failure;
- Some engineers in the industry sell tunnel design capacity as a primary business function but have very limited actual experience; and
- Some of the major underground contractors have engineers on staff, which enhances owner confidence that the best means and methods will be implemented.
Bases for Engineer-derived Means and Methods
Considering the fairly strong positions for avoiding engineer derived means and methods just highlighted may give the impression of an “open and shut” case. Yet, there are many situations where engineer derived means and methods seem to make good dollars and “sense”! They are briefly highlighted below.
- Owners own the ground – with legal rulings assigning ground risk to project owners it is a natural progression to also take on heavy participation in the means and methods to be used;
- Engineers study the ground for several months and in many cases for 1 to 2 years compared to contractors who study the ground for a 4- to 10-week bid period;
- It is difficult to separate means and methods from ground behavior. When something goes wrong it is very difficult to ascertain whether it is the equipment and/or contractor causing the problem or an unexpected response from the ground in the application of the equipment. As such, it is easier to simply direct the contractor on what was envisioned;
- A contractor may be inclined in a competitive bidding environment to use on-hand equipment and “make it work”;
- A contractor may make overly optimistic assumptions in a bid proposal in a competitive bidding environment;
- A spurious contractor (thank God we have few) may feel that loopholes in the specifications or GBR may result in a differing site condition claim to help recover costs not covered in their bid;
- Specifying certain equipment or equipment elements evens the field for all bidders. This presumes that doing so eliminates obvious inappropriate means and methods and the risk associated with them;
- Including engineer derived methods and methods in design documents often facilitates permit approvals;
- A customized/site specific tunnel boring machine is considered necessary for the anticipated ground conditions and the engineer has studied the ground longer than anyone;
- Bid comparisons are facilitated because few options are considered and the methods to be used are conceivably workable as they have been baselined in the tender documents;
- Presumably reduces owner risk of DSC claims in unproven ground conditions;
- Most of the project cost is in the methods of mining and excavation support so let the “guy or gal” who has studied it the longest direct them;
- TBM manufacture must be started during the design phase to meet schedule requirements;
- Often one design engineer is involved in the design of multiple tunnels in a given ground, yet the construction is completed by multiple contractors. The knowledge gained in that given ground is most often not transferred to the next contractor. Tunnel systems in the City of Atlanta and Cobb County, Ga., are examples of systems that involved a very limited number of designers but were all constructed by different tunnel contractors; and
- The excavation support needs to be considered in design of the final lining otherwise the final lining becomes extraordinarily conservative and may result in a much thicker concrete lining than is actually required when the excavation support and final lining are considered in a synergistic way.
One thing is evident from the various position statements, there is no clear “winner” on the subject and the decision may be more project specific than anything else.
The quote below, framed by the author, encapsulates the primary risk in specifying a method that forces the contractor’s hand.
“He who directs contractor means and methods may inherit some responsibility for them.”
Although there are real teeth to this quote, the perennial questions posed early in this article will certainly remain a viscerally disputed topic for the industry. No matter the position taken, at a minimum the design of an underground project should include a reputable construction lawyer, retired contractor, experienced third-party construction manager or other professional with directly related construction expertise. Preferably a mixture of these individuals is used.
When a decision is made to encroach on this traditional domain of a contractor, a risk/reward evaluation is prudent. That way a fully educated decision can be made. That evaluation must also include the residual risks that remain when the tender documents include designed means and methods. Additionally, if the design team does engage in some degree of prescriptive specifications, it is also a necessity to have a value engineering change proposal included in the tender documents. This mechanism will help to foster contractor innovation that may have been stifled by an engineer’s unimaginative means and methods specification.
The conditions of a contract typically set specific boundaries around the role of the contractor and role of the engineer relative to means and methods. Over-encroachment of these roles without modifications to standard general conditions may have legal implications including protracted litigation. Generally, the author is supportive of engineer’s design of means and methods in a blended specification as long as the conditions of the contract properly reflect that responsibility.
No matter what notions and beliefs one carries with regard to the issue of means and methods, the best projects are always those that involve a close and trusting relationship between the owner, engineer and contractor. Nothing else is more important in the final outcome. Healthy working relationships must be viewed in an almost sacred light to continue the incredible progress this industry has seen in the last few decades.
Don Del Nero, P.E., C.D.T., is with CH2M HILL and is based in Atlanta.
Hatem, D.J. 1998. “Professional Liability and Risk Allocation/ Management Considerations for Design and Construction Management Professionals Involved in Subsurface Projects,” Chapter 10, § 10.2.2 in Subsurface Conditions, D.J. Hatem, ed., (New York: John Wiley & Sons, Inc., 1998);
Reilly, J.J. 1997. Owner responsibilities in the selection of tunnel boring machines with reference to contractual requirements and construction conditions, Tunnels for People – Proceedings of 1997 World Tunnel Congress, Vienna Austria. Balkema. 1997.112. p749-756.
Tirolo, Jr., V., and Almeraris, G., (2005). Suggested and Prescriptive Means and Methods-Are They Really in the Owner’s Interest. Rapid Excavation and Tunneling Conference, 2005. C5. pp. 20-31