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Unknown Foundations

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FHWA Unknown Foundations Summit

Technology For Today And Tomorrow: Panel Discussion by Industry
Khamis Haramy, moderator

Panel Members:
Larry Olson
Darrin Holt
Ned Billington
Ed Mercado
Yajai Tinkey
Alan Rock

Khamis: I will ask the panelists several hard questions and I will the audience a chance to comment on every question:

Question 1: Over 86,000 US bridges have been identified as having unknown foundations according to the National Bridge Inventory. Many other bridges with unknown foundations also exist in Foreign Countries. Does the industry have the capabilities today to characterizing the type, size, depth, configuration, materials, and structure conditions of unknown foundations?

  • If the answer is YES-- What are these tools, applicability for different settings, capacity of the industry to conduct the work, and how successful are they?
  • If the answer is NO—What is the industry doing to provide these services? Or what should FHWA/State DOTs do to accelerate new developments in this field?

Larry Olson: Answer is yes, but lots of qualifiers. 2 limits: access to piles. Let's take 1 at a time. Type is shallow vs. deep foundations. [some audience agrees] research has been focused on that.. But you've got cost and risk assessment. Scan with radar, get footprint of that pile. Can't get buried pile yet, have to dig it up and look at it. Configuration, where are piles placed, without digging it up and looking at it. Germany doing a lot with re-using old foundations. Material, if can get access to it can determine by velocity. Timber varies, concrete varies. Structure condition, can get answers to most questions.

Darrin Holt: With technology available we can conduct analysis of piles below ground, but qualitative not quantitative. Buried footings.

Alan Rock: Lot of data collection tools that not looking at the big picture . Instead of just counting blows while driving rods, what about when they drive piles, why not put sensor on drill or on rods to collect as much information as possible…

Khamis: Larry talked about that earlier, for example the CPT.

Alan Rock: We have so many data collection techniques that exist, maybe we just try improve processing.

Ed Mercado: Agree with Larry. In oil, tech called 3D seismology. Borehole data acquisition is expensive, wouldn't want use it because of expense. Only technique besides tomography give 3d image.

Khamis: You expect this kind of answer from this group. They tell us something we like to hear, but maybe some of you tried it and didn't work.

Q: Limited number of companies doing the work and lot of work out there to be done. Until work can be packaged and put in hands of people with limited education, these tools are of dubious value.

Darrin Holt: Number of people in industry is correct. Very few of us, emerging industry, talking on order of 10-15 years. To handle volume, we call can't do 86,000 bridges. Lack of qualified people is true. Can we package into black box. All factors that take to do non-destructive testing is huge, and takes more than studying. Only understand it when worked for years in industry. We look for people to help us carry the torch. I have hard time find people I can train for 5 or 10 yrs. Need do every day or week get good at it. 10/20 years from now probably have black box. Our capacity limited by our manpower we have to solve. How much of chance we willing to take?

Khamis: Need shorter answers.

Larry Olson: it evolved where train people to obtain good quality data. Have specialists look at lot of data.

Khamis: We still need specialized people to process the data. Their answer was yes. How many of you (asking the audience) feel we have technology today and will hire one of these guys? [1 or 2 hands]

Q: Where are funds coming from? Won't get good quality info?

Khamis: Money is dangerous discussion. Money means different things. … it's important, but matter of urgency. : I've seen lots of DOTs pay the price.

Question 2: Has there been any new development in NDE methods and/or processing software in recent years that we are not aware of? (Are there emerging technologies and/or technology deficiencies).

  • If the answer is YES—What are these methods and have they been tested and where?
  • If the answer is NO—Is this an area where the industry can support on it's own?

Alan: There are new technology NDEs in other industries to be transferred over. Ultrasonic methods in welding. More communication with other industries, like the medical field. There are new developments come out all time, need look at other industries see what are and how bring them over.

Larry: Are new developments. If had to punch boring and check depth do it more economically. There are basic metal logging. Europeans look at how much can push technology to reuse building foundations.

Q: We have a major problem, have a bridge with unknown foundation, don't have time for being just nice to one another, need practical methods for what can we use so we can move on. Can't be more accurate than technical data we're using.

Ed: Accuracy of data depends on quality of data in first place. Lot of redundancy in data. As data redundancy increases need to balance off level of redundant data you want and then you have to pay for it. If pier is buried in mud and lots of rip-rap around it, diver can't tell you anything. I think always is how much money you want to spend.

Larry: I think what's lacking in engineers mind is ground truthing, which is a boring based test.. I encourage some ground-truthing. Until build it up you get some real confidence. [leaves]

Q: Grouping bridges together don't have to analyze all of them.

Khamis: We'll get into that tomorrow. Good point.

Q: Why need more than 1 method to investigate. In many applications, the best approach is stay open to multi methods.

Q: Lot of things can do without drill hole, but lot of things need to drill hole for. Can a bridge design from 30s handle specific load. Are there other ways of obtaining geological data?

Ed: Depends on geology of specific bridges. On parallel seismic method can get good handle on bridge and radioactive logging tools that are available, competent soil layer.

Khamis: There are several geophysical methods for that purpose.

Question 3: What role should the FHWA/State DOTs/NCHRP or researchers play to assure that we have the proper tools/advancement in the accurate characterization various types of Unknown Foundations? Different conditions, foundations, should we spend lot more money? Should FHWA spend $100 million? Should go after support from NCHRP, FHWA. Time to find good methods w/very high accuracy? Agree FHWA should spend money? [audience: yes]

What role should the industry play?

Ned Billington: Look at what's been done so far that Olson and others did. Lot of work done, more to be done.

Khamis: NCHRP spent about $3/4 million on report Olson did and didn't publish it. We spend lot of money, why was the report not published? Did we go in wrong direction on that? Should these guys go after NCHRP money? Keep evaluating same methods? Should we look at what oil biz is doing?

Ned: I support research. What can we do to reduce level of uncertainty?

Khamis: You did not answer the question.

Ned: I defer that question to those that do research.

Holt: Fund research not studies. Digital signal processing. Fund it at industry level as well as university level.

Yajai: Have 5-10 experts from industry come in and do blind prediction. Then invite the Panel to came and discussed what they found. More money, do test, presents results, then dig up bridges.

Khamis: You say different tests work in different conditions. You say we test all these methods. Does this method work and that doesn't?

Yajai: Learned about limitation.

Ed: Need funding make prototype to test on bridges. Only by doing test where can move from prototype stage to move forward. Need program to look at research gotten to prototype stage.

Q: Role of FHWA, they're way behind. When company comes and tell you we go have 90 percent accuracy. They tell you we can't give you what we want. They oversell their products. Don't deliver what promise. They say give us what we want.

Khamis: Ask this because FHWA took initiative put this together. None of you paid fees to come. FHWA want to know where are we today. Panel meeting on Thursday to refine this. Where are we today?

4: Are these statements valid:

A) The actual type of NDE method chosen has been project specific depending on access, foundation configuration, nature of subsurface soils, and the skills and equipment of the practitioner.

Holt: Strongly agree.

Ned: But cost goes, up can't do it all the time. Drilling and casing of bore-hole drives cost up. With CPT/PS do multi bridges at once. There are levels of uncertainty.

Q: Boring is important because can't use CPT in Hawaii. Interested in quality of piles, not depth. Pounded down before it hit refusal. Want figure out how get more out of it. Is that all we need?

Khamis: Good question. Quick answer.

Holt: Use parallel seismic. If want do it for all piles , xxx. To do for pile group only get selective xxx.

B) NDE methods are cautiously evolving and interpretation is still somewhat subjective based on the interpreter's judgment and experience.

Holt: Strongly agree.

Khamis: Only 3 or 4 companies are doing this work.

C) NDE methods for unknown foundations are generally not reliable and relatively expensive. FHWA policy makers and US Transportation Departments should abandon the use of NDE for unknown foundations and rely more on risk-based analysis and bridge retrofitting with countermeasures.

Ned: No, seen lot of success w/NDE methods. Doesn't work with every case but better than nothing. In terms of cost, with research and testing, we collecting data and give to DOTs and they do risk-based analysis. Talk about do RBA, but what go base that on? Looked at bridges xxx. Tough to go from broad assumptions.

Khamis: skip question on cost benefit.

6) One of objectives of this summit is for the policy makers to gain knowledge that will assist them in the development of guidance and management strategies based on the outcome of this meeting for state DOTs and other bridge owner. A committee will be formed for this purpose immediately following this summit. If you were part of this committee, would you incorporate the use of NDE as measurement tools for Unknown Foundations? If so at what capacity?

Ned: Yes, I'd incorporate NDE methods as part of tool box. Some type of risk-based analysis.

Alan: I'd look how can we take existing working methods, make more objective, and automate them. There's enough knowledge from this group that's been amassed to use it. Go in direction of automation and objective analysis. Subjective methods, put into automated analysis system. Can be done.

Holt: A good UF program … Let's look for info, and then get together and talk about it when can't find it. Gather all info and sit down and discuss. NDT I'd categorize as field work. Do 1 hour for document search per day.

Ed: Bulk of expense is in data gathering. Get payback from invested funds to improve data acquisition.

Yajai: If have 100% reliability, cost is zero, everyone do it. Cost-benefit is key.

Ned: Depends, very site specific.

Yajai: That's it. Define expensive. It's less expensive than lawsuits. Keep costs down by doing testing at same time.

Q: Don't have way telling us how to get to design factor. Research needs to focus on encompassing value structure. Can't focus on one little piece.

Q: From owner standpoint, have whole bunch of bridges to look at, to go from experimental to production level. Where experts are actually needed. Bring experts in for interpretation.

Khamis: Is Alan Rock's work worth the investment?

[majority of audience raises hands]

Adjourned 5:03

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More Information


Silas Nichols
Office of Bridges and Structures
E-mail Silas

Joe Krolak
Office of Bridges and Structures
E-mail Joe

Updated: 04/07/2011

United States Department of Transportation - Federal Highway Administration