×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Engineering Judgement vs. Codes
2

Engineering Judgement vs. Codes

Engineering Judgement vs. Codes

(OP)
Here is a hypothetical situation which has generated much discussion among a few of my colleagues. When, if ever, should engineering judgement take precedence over legally adopted design codes or standards (i.e. building codes)? For example, if during the design process you encounter a situation where following a code would be detrimental to public safety or result in an uneconomical design are you still required to adhere to that portion of a particular code? As an engineer, could I over rule a building inspector's decision, who probably has no formal or technical education in engineering? If I am under a contract with the owner to provide design services, am I still obligated to follow the code and seal the drawings if I believe that the design is flawed due to following  the code? I know that in most codes there is are statements that say something like "in lieu of a more detailed analysis based on engineering principles......." which provides a loophole, but this is not always the case.

RE: Engineering Judgement vs. Codes

Most model codes are written with the concept in mind that if followed by non-engineers, the result will be adequate to protect the health, safety and welfare of the public.  As engineers, we know this to be a fallacy, as many of the code provisions require engineering interpretation.

Having said that, the code often becomes construed as the "minimum standard of care" and to deviate from it puts additional liability on the engineer.  We all know that there are times when engineering judgment should supercede certain provisions.  My suggestion would be to document both sides of the argument, so that if an issue is raised at some point in the future, then there is a clear path as to the decision process.  

Also keep in mind that if the code is not followed and there is a failure, the logical assumption is that if the code HAD BEEN followed a failure would not have occurred.  This too, is sometimes a fallacy.

RE: Engineering Judgement vs. Codes

I don't know about building to code, but with cars we /have/ to meet various legislative requirements, engineering judgement or not.

I have heard of cases where cars have been succesfully homologated,  even though they did not meet all the written requirements, but not on anything safety or emissions related.

We also have internal standards which are substantially more restrictive than the legal ones, but we can design a car that breaks these standards, so long as we can demonstrate that the sub-standard performance still satisfies the customer's requirements, etc.

 

Cheers

Greg Locock

RE: Engineering Judgement vs. Codes

Engineering codes of ethics hold public safety paramount. Economics, however, is not paramount.

RE: Engineering Judgement vs. Codes

A good many of the things in building codes have a dead person or two behind them.  If you have a valid reason to change something in a code you can apply for a variance in most jurisdictions.   You have to state your case and the reasons you want a variance.   If it's logical you'll probably get it.
  A lot of plans inspectors and building officials see things differently than engireers. Their experience and training is more focused on public safety than efficient or seemingly good design.  
Everyone knows why doors of nightclubs open outward ( the Coconut Grove fire )but there are lots of other seamingly trivial things that can have an impact on public safety.  Lots of people don't know what they are and the rules in place because of them.

RE: Engineering Judgement vs. Codes

MotorCity, I guess I don't see the dilema here.  As an engineer, you have a duty to protect the life and safety of the public (per Ron above).  

Building codes set minimum standards.  If you see something in the code that to you feels TOO minimum, just increase your design accordingly.  You can then show that you have met the minimum design required by the code, and you even went the extra mile to increase the design due to your judgement.

RE: Engineering Judgement vs. Codes


Code is not god. Codes are created by human beings and human beings sometimes make mistakes. Part of the reason that our engineering education is structured the way it is, is to teach us to think. I meet too many engineers who blindly design to code without knowing the limitations and applicability of code. I suggest examining the code in detail, try to find out why it is the way it is, learn the limits of its applicability, find out the assumptions that are utilized. A good engineer questions everything and assumes nothing.

RE: Engineering Judgement vs. Codes

Gosh, when you were designing a steel structure did you  measure the young's modulus of the steel? Did you also build the instrumentation used to emeasure the Young's modulus?

I think your final sentence is silly.







Cheers

Greg Locock

RE: Engineering Judgement vs. Codes

Greg - which post are you referring to?

RE: Engineering Judgement vs. Codes

He's probably referring to "A good engineer questions everything and assumes nothing."

TTFN

RE: Engineering Judgement vs. Codes

Did the initial question refer to a case where the code didn't go far enough, or where a better structure would actually be in violation of the code?  If it's the second, can you give a little more information?

Hg

RE: Engineering Judgement vs. Codes

(OP)
Just to clarify a few points:

1. I agree 100% with the fallacies Ron described.
2. Public safety and protection is not an issue, as
   everyone agrees that this should dictate the design
   above all else.
3. I also agree with JAE in that providing the minimum
   (or more) as required by code is the way to go when
   possible.

The point I was referring to is a case when a safer structure, in the opinion of the engineer, would result if it were in violation of a particular code requirement. I think that its not a matter of if the code goes far enough, but rather if it goes too far in some cases. I do not have a particular situation in mind, it was just a question discussed among fellow engineers. I hope this makes the topic more clear. Any other thoughts?

RE: Engineering Judgement vs. Codes

I'm just having trouble coming up with a hypothetical situation.  Not that I probably haven't come across them, I just can't think of any at the moment.

Hg

RE: Engineering Judgement vs. Codes

It seems to me that there are two directions to this thread, firstly if the hypothetical situation is purely that, hypothetical, then surely it is basically a philosophical debate on whether an engineer can justly disregard a section/s of code and for what reasons. If that is ever the case then the code that is in conflict with the engineers views could be in need of ammendment.

Secondly, if Motorcity (or anyone) has become aware of a situation (via hypothetical reasoning or otherwise) where there is a genuine deficiency in a code that could give rise to a safety issue then surely it then becomes a duty to bring this to the attention of whatever body is responsible for maintaining the code. Codes do evolve to reflect changing developments in materials / methods etc.

Afterall is not the hypothetical situation (if Motorcity had a specific design or structural problem in mind) a form of FMEA ? albeit informal in this case, and are not the codes (generally) the result of formal FMEA and real tragedies, written to prevent failures happening again ?.

RE: Engineering Judgement vs. Codes

Codes especially design codes are devloped based on considerable research and experince. Provisions are often developed to address actual problems or failures. On the other hand, Natue is fixed, yet the code is constintly evolving, so obviously we are still figuring out exactly how buildings work. Look at the significant revisions to the seismic codes. Codes are not perfect. Further they are written in the abstract, a design guide for projects yet to be concieved. It is possible you have concived of a structure that requires an application of the code not anticipated by the writers that in your situation may not be safe. My advise would be to thoughly analyze the situation so you are convinced there is a problem. Then call the agency who wrote the code. They can probably put you in touch with some one on the committe that is responsible for the provision. Explain the problem to him and listen to the response. If you are still convinced,lay out your reasons carefully and clearly show the varrience on the plans. Then meet the building offical to explain it to him. It will be much easier for him to approve it if he has not rejected it first. My answer is that if you feel the code is wrong for your application, you should do what is prudent, but be sure you are right.

RE: Engineering Judgement vs. Codes

That's what I was wondering--whether there's a situation at hand that might warrant changing the code in question.  

I've gotten a number of minor code changes through various bodies by pointing out some discrepancy or other to people in the position to change things.  It can be done.  If what you have is a weird enough case, though, they would probably say that's not an intended application.

Most contracts, codes, specifications have an option for "the Engineer" to allow exceptions to the code, so your hypothetical situation could be handled under that provision.  Just document the hell out of it--if applicable, show calcs both ways demonstrating that what you did is better, and also set down in words the overall logic of your reasoning.

I'm having a major "d'oh!" moment here--most of my job involves handling exceptions to codes, just on a more minor level than I'd thought you were talking about.  And very often we'll let something go that's in violation of the spec but still structurally adequate, because the cure may be worse than the disease--for example, a small area reduced in thickness because a defect was ground out often isn't worth introducing a welded repair to the area.  Dunno if that answers the original question.

Hg

RE: Engineering Judgement vs. Codes

Over a decade ago a doctorate level chemical engineer from a different office identified a flaw in API RP 520 for sizing safety relief valves.  His sizing requirements included partial differentials for the correct solution.

I supervised over 40 engineers at that time.  I advised that we would follow API RP 520 which is a requirement of many of our contracts.  I also recommended that the PHD type should present his concerns to API.  As far as I am aware no change occured.

Still, the use of engineering judgement is also required.  We often speak of codes and standards.  As with many standards, the API standard mentioned is a recommended practice.  It is common for standards to include verbage that permits exceptions.  Document deviation well, distribute to those in authority and proceed with approval.

John

RE: Engineering Judgement vs. Codes

JOhn,

Was the API method more or less safe than that established by your "Chemical engineer doctor"?

Regards

James

RE: Engineering Judgement vs. Codes


Interesting post.  Getting away from the structural aspects of building codes, I can give you a good example of deviation of code and applying for a variance.  The handling of fuels, specifically the dispensing of gasoline, is strictly forbidden indoors.  However, we at a car assembly plant dispense gasoline as the cars near the end of the assembly line to enable driving off and facilitate vehicle testing.  Our case for dispensing gasoline indoors is logical and by showing that our equipment, methods and safety precautions exceed the code for the handling of fuels, we had no problem obtaining a variance.  This of course is not a unique situation, as every vehicle assembly plant in the world does the same thing.  I think the point is that had we not applied for a variance, regardless of our equipment, methods and safety precautions, we would have been in violation of code.  Maybe the scenarios are not parallel but as codes are written by engineers and variances granted by engineers when the design and safety criteria exceeds minimums, the inspector's black and white interpretation of deviation/violation of the code means nothing.    

RE: Engineering Judgement vs. Codes

"Public safety and protection is not an issue.."
"The point I was referring to is a case when a safer structure, .., would result.."

Can't have it both ways. Either safety is an issue or it isn't. If it is an issue, it must come before code requirements.

RE: Engineering Judgement vs. Codes

The poster posited a structure that is "safer" than than a compliant design.  

A compliant design is assumed to be "safe" and is therefore indeed not a safety issue.

TTFN

RE: Engineering Judgement vs. Codes

I would propose that an engineer's obligation to public safety doesn't end with a code making committee's today's definition of "safe." "Safer" is always a desirable goal. Codes by nature lag technology, and engineers can affect changes.

"...if during the design process you encounter a situation where following a code would be detrimental to public safety..."

Sounds like safety is very much an issue. Can't have it both ways.


To take this beyond the hypothetical:

A clause in the 1997 and earlier versions of the National Electrical Safety Code was being interpreted in a way I considered to be detrimental to the safety of construction workers in an electrical substation. I let the committee know in a letter, and proposed an exception. The committee took my exception and added to it. See exception 3 of rule 110B in the '02 NESC, and IR507.
 

RE: Engineering Judgement vs. Codes

JamesCG,
The chemical engineer claimed that the error in the API standard was unsafe - his method safer.

John

RE: Engineering Judgement vs. Codes


The issue is:

Do you follow the letter of the law, or the intent of the law?

In my mind, the intent of the law is paramount.*  

Justifying such a departure from code -to establish the true intent of the law- would at a later time be easier to explain than, in this context, justifying blind legalism.


* If the law (code) is properly written, the intent becomes the letter.

RE: Engineering Judgement vs. Codes

Specific to the Canadian National Building Code, there is something called an equivalence which can be demonstrated by an engineer.  A large chunk of our companies activities and from developing equivalences.

There are many mistakes/holes in the NBC and NFC in Canada, engineers don't generally exploit them but others using the code sometimes do.

Even worse are mistakes in some of the local authorities regulations.  They do not grant equivalencies.

A specific example is in Nova Scotia, the NS Building Code Regulations that append the NBC require limits placed on building occupany not based on the exiting provided but by using the design factors for minimum exit standards.  No credit is given for providing additional exiting from room.

This is a serious limitation making it near impossible to allow graduation ceremonies in gymnasiums etc even if sufficent exits are designed and provided. The authority looks at the table showing the minimum design loads for exits and makes that the maximum number of people permitted.

The funny thing is the table they reference has an appendix entry explicitly saying the table is not intented to limit occupant loads and that it has been mistakenly used to do that by authorities.

Ken

RE: Engineering Judgement vs. Codes

     Follow the codes to the letter - then sit back and let our wives and building inspectors design.  For if the code designs, what is our purpose?  
     I have seen several times where codes are being followed and the resulting design is garbage - why?  The code didn't identify some peculiar point that the actual site condition had - like adjacent footings.  Or, the code requires, say 40kg stone for slope protection when engineering tells us that 1kg stones is sufficient. In other words the codes were inappropriate, yet they were codes so . . .  
     I took up geotechnical engineering years ago because they didn't have many if any codes at the time.  I would be surprised if any of the great advances in geotechnical engineering by the pioneers would have been possible if they were constrained by codes.

RE: Engineering Judgement vs. Codes

I like how EddyC put it his/her post, only with a subtle change...Codes were created by engineers for use by laypeople....We make the codes and we can design around them if good engineering practice dictates.  We then take responsibility for the design....After all this is what it means to be an engineer...

BobPE

RE: Engineering Judgement vs. Codes

Interesting thread.
motorcity asks 'if...you encounter a situation where following a code would be detrimental to public safety...'.
This is a hypothetical situation, and I can't think that there could be many cases where this would apply.  Usually codes specify a minimum standard of safety.  Exceeding this minimum is rarely a problem.  If the code were to actually prohibit something that could improve safety, then it would be necessary to understand the reason for this.  It might be possible to get round it, but only by following some very definitive steps.
If the code tells me I have to use a 40kg stone, then I think I would tend to use 40kg stone rather than a 1kg stone, even if that was all that was really required.  I would, of course, make sure I fully understood the code first to make sure that there were no get-out clauses.  But I think it would be cheaper and easier to do that than try to convince my insurance company that the code is excessive, or worse still persuade a judge and jury that 1 kg is adequate for the worst reasonable design case and that it wasn't reasonable to design for the 500 year storm that just hit.  If using a 40 kg stone compromised safety on the other hand...

RE: Engineering Judgement vs. Codes

TrevorP - the 40kg stone is a safety hazard to the poor 50kg worker who gets the hernia carting it about!  I understand your point but there are some codes that rely on "the bigger the better", "the more the better".  To compact an expansive clay to 95% modified Proctor is asking for problems once the moisture content increases and causes excessive swelling - still, the spec says to do it.

RE: Engineering Judgement vs. Codes

BigH:

If you are the engineer, change the code and stand behind your decision for all to see....it is that simple...

BobPE

RE: Engineering Judgement vs. Codes

BobPE - I'm happy to do it - but sadly, I don't have the final say as I am not the "Engineer" (as per FIDIC or contract) and so so many worry about the "auditors."  I fight my battles when I see I have a chance to win.  Thanks for the back-up!

RE: Engineering Judgement vs. Codes

"I can't think that there could be many cases where this would apply"

Think harder. The code writing bodies are made of reasonable people, but they cannot possibly imagine all of the interpretations the AHJs will put them to. A little feedback, and they'll close off a misinterpretation or two in the revision cycle.

My October 4 example involved the temporary storage of an electrical vault in a substation yard. The  first suggestion by the AHJ was to move the vault outside the substation fence. We patiently explained that the vault was slowly filling with rainwater, and that making it easier for kids to drown would certainly not enhance public safety. Their second suggestion would put workers at risk.

RE: Engineering Judgement vs. Codes

An example of code not accommodating reality:  A building being built on, or retrofitted with, base isolators, total motion being up to 18" horizontally from rest position.  Code requires that flexible conduit in service entrances be limited to six feet.  That range of motion can not be accommodated in only six feet of 4" flex conduit.  The risks of an energized service entrance feed being ripped asunder during a seismic event are far greater than those associated with using more than the code permitted amount of flex conduit.

RE: Engineering Judgement vs. Codes

Aha, a few good exceptions to prove the rule...(and aren't these always the most interesting?).
Please note the phrase - "I can't think there would be many..." rather than "I can't think there could be any...".
Anyhow, I can't think of anything more valuable than getting the code changed where necessary - so a star for stevenal for that!  
Actually, by doing this, you followed what I was meaning by 'definitive steps' - to the end point.
My point was really that, if it is merely an inconvenience to follow a code, then you do so at your own peril.  Legislation is becoming more and more onerous all the time, and public expectations of safety higher and higher.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources