This is an old subject that I first dealt with back in the mid-80's when CAD was in it's infancy. I am really surprised that ASCE hasn't seen fit to address the issue directly.
The real issue here is, what did the Engineer of Record Certify as his design? If the EOR actually prepared the CAD files, and is confident enough of his ability to do so, then he may decide to release his/her files for more detailed construction reference, such as stake-out. But if he reviewed the paper plans generated by CAD staff, and approved only the visual representation of the proposed construction, with annotations as to layout, etc., then you have another situation. Issuing the CAD files for stake-out means the CAD Technician is now the designer of the project. If a feature is to be constructed 10 feet parallel to another feature or property line, and the notation says so, but the CAD Technician fudged his drawing such that the coordinates say that it will be 9.75 feet parallel, and the CAD file is used for stake-out, then the construction would not comply with the EOR's design, for example. The EOR would never have known that the drawing was wrong.
Design surveys have been containing errors since the dawn of engineering design. It happens, and can't be avoided. But the careful layout of a project based on the EOR's design will usually result in the identification of those errors, and provide an opportunity for correction. The exclusive use of CAD files only serves to cover up those design survey flaws and result in a completed project that may not be what anyone wanted.
Since the advent of computers in design, there has been a tendency to accept the computer output as defacto and correct. I have had to send young engineers back to the drawing board many times when their results were obviously off by a significant amount, such as 3 decimal places in computing stormwater volume - something they never even looked at, because "The computer said so". Computers must be used carefully as a tool for design. We still aren't to a point where the computer can d the design.
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Joseph Brown P.E., M.ASCE
Engineering Consultant, Retired
Tallahassee FL
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Original Message:
Sent: 02-27-2018 11:28
From: David Thompson
Subject: Coordinates for Layout
The challenge in providing electronic documentation is the change in mind set all around.
Using paper documents there is an established procedure where all the checking points for accuracy are accepted both during design and construction. Within this qc frame work acceptable time lines for providing information are known. With electronic information provided the checking that was done during construction is not as thorough, The contract drawings are now expected to have the accuracy that was expected for large scale details to be carried to the plans. For complex structures that means locations have to be drawn to the mm (0.04 in). The computing power to tie all the details into the plans on large projects is not there. Also the need to provide and pay for time to carry out all the impacts of a dimensional change is not recognized.
In the case I mentioned earlier, the information on the change would have taken 40 hours of work to revise the complete plans and details. We were provided with it 24 hours prior to tender with the statement it should not be any extra design cost. The large scale details could be fixed in that time but the pile locations could not be moved on the plans. However the pile locations using the plans and large scale details could be located.
The Construction Manager only gave the plans to the surveyor.
The point I am trying to make, is that there has to be a change in Mindset of everyone involved (owners, consultants and both general and sub contractors) on how to work out the time lines and costs in doing electronic projects.
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David Thompson P.E., M.ASCE
Principal
KTA Structural Engineers Ltd.
Calgary AB
Original Message:
Sent: 02-26-2018 00:37
From: Stephen Hemphill
Subject: Coordinates for Layout
In my experience, there is a positive correlation between those who resist providing accurate (read CAD) plans and those who want to charge extra for fixing design problems during construction. Although it can not always be expected in an atmosphere of Engineer selection by less than knowledgeable officials instead of the owner's (or truly independent) engineers to afford competent designers, at some point it will have to be acknowledged by upper management that cheapest is not always the best bang for the buck, as engineering costs are typically only 10% to 20% of construction costs.
It is not that rare for construction extras to exceed design costs. Back-calculating station/offset from lat/long is just not that difficult.
Of course it should always be mandated for the Contractor to confirm geometry by a Surveyor (and underground utility locations) prior to beginning Work, which should negate idle equipment time extra charges.
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Stephen Hemphill
Rio Rancho NM
Original Message:
Sent: 02-23-2018 08:49
From: Karl Sieg
Subject: Coordinates for Layout
Recall that old Manual 45 advised that fees should be at least 35% higher for work involving existing structures.
Although the courts erroneously ruled the curves relating engineering costs to construction costs to be unlawful price fixing, the information in 45 is still valuable.
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Karl Sieg P.E., M.ASCE
Sieg & Associates Inc
Wexford PA
Original Message:
Sent: 02-22-2018 12:04
From: Michael Byle
Subject: Coordinates for Layout
I think there is a big difference between a green-field project and a project involving existing structures, where all details and dimensions may not be completely discoverable until during construction. Regardless, Denis O'Malley asked how we can convince our clients to pay for additional efforts to make drawings more complete. The question is not how to convince our clients, but how to convince the design community that it is not acceptable practice to provide less comprehensive plan sets. If we don't agree on the minimum acceptable level of work product, the one with the lowest standards is the one who wins the project and lowers owner expectations. This devalues all engineering.
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Michael Byle P.E., D.GE, F.ASCE
Tetra Tech Inc.,
Langhorne PA
Original Message:
Sent: 02-21-2018 09:03
From: Rosser Standifer
Subject: Coordinates for Layout
The use of coordinates increased as CAD became common place. The question is generally whether their use is appropriate on a given project. Coordinates are a bit like schedules (tables) in plans and specifications. If thoroughly quality controlled they'd work perfectly without dimensions, that of course would only work in a perfect world. As Shelly alludes to it is the dimensions that allow the Owner and Contractor to confirm the design intent of the Engineer. The goal is after all a successful project. Proper dimensioning of a layout, with some coordinates to allow the Contractors surveyor to quickly complete initial staking or locate corners of individual components of the work is good practice.
Transmittal of electronic files requires caution. Our product designs in most jurisdictions bear a seal. Laws typically place the responsibility for restricting access to the sealed editable design files on the Engineer. Thus, while we may allow distribution of the design or related model files after removal of the seals, paper (or PDF) designs aren't going away soon. It must remain the Contractor's responsibility interpret the electronic data and determine if it matches the sealed design he/she agreed to complete when signing the construction contract. We should resist the temptation to free distribute editable files, there must be a reason behind the Contractor's request. Hopefully one that clearly increases his/her efficiency such as their use in driving grading equipment.
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Rosser Standifer P.E., M.ASCE
Senior Project Manager - Conveyance
Alan Plummer Associates, Inc.
Dallas TX
Original Message:
Sent: 02-16-2018 13:04
From: Shelly Hattan
Subject: Coordinates for Layout
I have to ask if other folks are seeing a trend with horizontal layout sheets.
I was trained to include control points along with bearings and distances. We used to also dimension the hell out of drawings. The Rule of Thumb I was given was to imagine having to be in the field to lay out the project and to provide information that an inspector could use to verify dimensions.
I'm seeing that go the way of the dodo.
Seems like engineers are providing points with coordinates now. That and they're providing CAD files, too.
With GPS units being somewhat ubiquitous on construction sites, I also see contractors not hiring honest to goodness surveyors.
I feel like I'm seeing more busts with layout than I ever did in the past. Anyone else seeing the same thing?
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Shelly Hattan P.E., M.ASCE
Tarrant Regional Water District
Fort Worth TX
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