When engineered structures fail, who’s to blame?

I recently wrote here about the engineer’s right to select the preferred pipe for a specific project. The fact is, it’s outrageous and unfair to hold design engineers responsible in any way for failures in infrastructure when the decision to use this or that component was made by others. 

Of course, frequently, with blame comes actual liability, and this raises the question of the potential financial liability of a design engineering firm — or even of an individual design engineer — in a case where a structure fails as a result of a poor choice of component. When the selection of this or that component is made by a political committee, or by a procurement office, or by any entity other than the design engineer or design engineering firm, then liability should fall to that entity, and not to the engineer.

If the right to choose the component part is removed from the engineer, then so should the attending liability. It just makes sense. 

Recent failures in the news

I don’t really know if structural failures are becoming more common, or if they’re simply being reported on more frequently, but there have been a couple of serious structural failures here in the U.S., which should perhaps act like the canary in the coalmine. In other words, we appear to be entering an era of failures and disasters where engineering decisions seem to have been either wrong or simply ignored. One of these actually involved pipe, while the other did not. 

Perhaps the most obvious example was the 2007 failure of the I-35W bridge. Thirteen people were killed and 145 were injured. In this case, a well-known international engineering firm ended up paying $8.9 million to the State of Minnesota, which had set up a compensation fund. The firm admitted no wrongdoing, and wasn’t even the firm that designed the structure — the international firm had in 1999 acquired the design firm that originally designed the structure in the 1960s. But the company chose to settle for the $8.9 million to avoid further litigation costs. While admitting no liability, the financial award was so significant that it would put a nasty dent in almost any engineering firm’s bottom line.

Fishy business in Texas

In 2009, some parts of a drainage system had to be replaced in at the John D. Parker East Texas Fish Hatchery in Jasper, Texas. A roughly two-mile length of the original high-density polyethylene (HDPE) pipe had collapsed, and a further 11,000 feet of pipe was discovered on inspection to have poor structural integrity. The HDPE pipe had to be replaced with reinforced concrete pipe (RCP), which is a structure in its own right, and thus won’t collapse under the weight of overfill or other pressure. Following a legal settlement, the hatchery’s design firm had to pay more than $3.3 million, which was almost the entire replacement cost. This pipe replacement delayed the project schedule by an entire year. 

This settlement raises an interesting question, because the manufacturer of the HDPE pipe wasn’t part of the hatchery settlement at all. Almost the entire financial responsibility for the failure fell on the design firm. I checked out some of the information provided by a random selection of HDPE pipe manufacturers, and several of them made claims regarding the structural integrity of the product. One manufacturer, for example, uses the phrase “unsurpassed structural integrity.” 

I find this rather debatable. Properly installed, HDPE/PP can deliver overall structural integrity, but the pipe itself only contributes a small fraction of the structural strength, while the remainder is a function of the embedment material used and the compaction efforts undertaken. Correct installation is vital to the overall structural integrity of any finished pipe product. Precast concrete structures and reinforced concrete pipe (RCP), on the other hand, are rigid structures in their own right, so correct installation is a less critical part of the overall structural integrity of the system — although proper installation is still required for the system to perform as designed. In other words, the structural integrity of HDPE/PP pipe is definitely surpassed by RCP, though you wouldn’t think so from the manufacturer’s claim. 

Discovering that the structural integrity of HDPE could indeed be “surpassed” was a more than three-million-dollar lesson for the fishery design firm. 

The question of responsibility

My point is this, if design engineers are going to be held responsible for outcomes based on engineering performance, then they must also have the right to make the engineering choices involved. It strikes me as grossly unfair, for example, to take the choice of pipe material away from the design engineer, but then hold that same design engineer liable for subsequent material failures. 

If other bodies — for example, political bodies, purchasing departments, procurement officers, or others — wish to remove the responsibility for making the design choices, then they must also remove all future liability for failures or expenses incurred by that selection. That’s simply common sense. 

Pressure from the outside

As we all know, our water and drainage infrastructure is in horrible shape. Many systems that were installed decades ago are still in service, despite being due for repair or replacement many years ago. Utility owners are often stuck between the rock of system deterioration and the hard place of political reluctance to raise taxes or fees to cover costs. The result has often been procrastination. When the manufacturers of cheaper pipe promise that their product is able to perform equally with the traditional material, it’s music to some decision-makers’ ears. Finally, they can tackle the problem without breaking the bank. The only problem is this: if they’re using less rigid, less long-lasting, less structurally reliable material to do the job, then the savings may be as long-lasting as they were in the case of the Texas hatchery.  

Design engineers know the difference between an intrinsically rigid structure and an installation that must be made rigid using embedment material and careful installation procedures. If the decision is to go ahead and use the non-rigid alternative, then whoever takes that decision out of the hands of the engineer must also shoulder responsibility for future performance and maintenance costs. 

The right to choose

As I’ve written about before, there’s a reason why design engineers have to study for many years learning their skills. Engineers continue to gain knowledge as they acquire practical experience, past and present. Engineering is a difficult business, and the selection of materials should never be a casual one. While purchase price will always be a factor in choosing pipe material, there are also other vital considerations, not least of which are performance, reliability, planned longevity, maintenance and total life-cycle costs. RCP, for example, has a verified design life of well over 150 years, and is designable, which offers many options to the design engineer. Engineering standards and correct installation procedures are balanced with many other factors — just one of which is purchase price — before a decision to specify this or that pipe material can finally be reached. 

Can you imagine the outrage if a doctor’s medical opinion should be changed by a political body, purchasing department or procurement officer? For many reasons, not least the matter of future liability, the design engineer must retain the right to choose material. To do otherwise is taking a huge risk, and is simply wrong. 

Branimir Kovac, VP, Thompson Pipe Group

P.S. If you’re interested in learning more about a complete range of pipe products from Thompson Pipe Group, visit www.thompsonpipegroup.com. You can sign up for our monthly Pipeline e-newsletters here.