1 00:00:00,100 --> 00:00:07,070 I’m Norbert Morgenstern, past president of ISSMGE 2 00:00:07,150 --> 00:00:12,500 The video that you are about to watch were first filmed in 1991 3 00:00:12,550 --> 00:00:18,750 with the attempt to capture action leading lights in Geotechnical practice and research 4 00:00:18,800 --> 00:00:23,500 Dr. Ralph Peck was an obvious candidate for this enterprise 5 00:00:23,550 --> 00:00:30,650 given his international status as educator, researcher, and consulting Geotechnical Engineer 6 00:00:30,700 --> 00:00:38,250 Dr. Peck passed away this year on Feb. 18, 2008 at the age of 95 7 00:00:38,300 --> 00:00:43,170 He leaves a legacy of countless students, colleagues, and clients 8 00:00:43,175 --> 00:00:46,165 who inspired by his wisdom and humanity 9 00:00:46,170 --> 00:00:54,700 As Dr. Suzanne Lacasse, managing director of NGI wrote in a moving obituary 10 00:00:54,710 --> 00:00:57,405 we say thank you for the life you lived 11 00:00:57,410 --> 00:01:01,350 for sharing with us your intellect and your patient for soils 12 00:01:01,355 --> 00:01:04,180 Geotechnical Eng., and Civil Engineering 13 00:01:04,185 --> 00:01:08,577 We all enriched, not only by the contents of your contribution 14 00:01:08,580 --> 00:01:12,890 but also by the style with which you practiced your profession 15 00:01:12,895 --> 00:01:18,505 We’re fortunate that the only two years ago the breed of Ralph Peck’s humanity 16 00:01:18,510 --> 00:01:23,355 and his technical contributions were captured in a biographical volume 17 00:01:23,358 --> 00:01:26,565 edited by Nancy Peck Young, his daughter 18 00:01:26,570 --> 00:01:33,005 and John Dunnicliff, a well-known consulting Eng., and past student of Dr. Peck 19 00:01:33,009 --> 00:01:36,400 It is titled; “The Essence of the Man” 20 00:01:36,405 --> 00:01:41,365 after viewing this video and seeking additional guidance 21 00:01:41,367 --> 00:01:45,590 on the art and science of Geotechnical Engineering 22 00:01:45,592 --> 00:01:49,807 you may wish to consult this volume to better understand 23 00:01:49,810 --> 00:01:53,980 the essence of Ralph Peck and his profound contribution 24 00:01:53,985 --> 00:01:56,000 Thank You. 25 00:02:42,865 --> 00:02:46,310 This video marks a new venture on the part of our society 26 00:02:46,312 --> 00:02:51,105 together with BiTech Publishers; we are launching a series of videos 27 00:02:51,106 --> 00:02:54,540 entitled “Leaders of Geotechnical Engineering” 28 00:02:54,542 --> 00:03:00,820 Geotechnical Eng. combines Soil Mechanics, Rock Mechanics, 29 00:03:00,824 --> 00:03:04,614 and Engineering Geology in a wide range of endeavors 30 00:03:04,615 --> 00:03:09,405 that spans from solely theoretical and abstract activities 31 00:03:09,407 --> 00:03:12,634 to the more practical and empirical 32 00:03:12,635 --> 00:03:18,702 While our rich literature is capable of reflecting the technical content of our activities 33 00:03:18,703 --> 00:03:22,670 it is generally unable to embrace the human element 34 00:03:22,672 --> 00:03:28,207 Indeed modern technical writing goes to some effort often to eliminate it 35 00:03:28,208 --> 00:03:34,205 The translation of Geotechnical concepts in the very important engineering works 36 00:03:34,309 --> 00:03:39,623 of our time is not undertaken by conforming to preset rules 37 00:03:39,624 --> 00:03:44,980 but instead relies on the imagination and leadership of our teachers 38 00:03:44,982 --> 00:03:47,710 researchers, and practitioners 39 00:03:47,712 --> 00:03:54,559 It is the intent of these videos to not only present material of lasting technical interest 40 00:03:54,560 --> 00:03:57,927 but also deal beyond the purely technical 41 00:03:57,928 --> 00:04:03,812 and capture the personality, humanity of leaders in Geotechnical Engineering 42 00:04:03,814 --> 00:04:07,140 who have given so much to our subject 43 00:04:07,141 --> 00:04:11,085 To do this, we’re inviting well-known Geotechnical engineers 44 00:04:11,086 --> 00:04:15,998 to donate their time and assist us in filming the series 45 00:04:16,000 --> 00:04:19,167 In this way, we hope to create a visual archive 46 00:04:19,168 --> 00:04:25,269 that is of lasting interest and it captures the science, the art, and the personality 47 00:04:25,270 --> 00:04:26,780 of Geotechnical Engineering 48 00:04:26,781 --> 00:04:30,920 We are particularly pleased that Dr. Ralph Peck 49 00:04:30,921 --> 00:04:35,349 has agreed to assist us in filming this 1st video in the series 50 00:04:35,350 --> 00:04:40,690 The contributions of Dr. Peck and awards that he has received 51 00:04:40,691 --> 00:04:43,512 are too numerous to be detailed here 52 00:04:43,513 --> 00:04:49,005 Ralph Peck as a teacher, as a researcher, and as a practitioner 53 00:04:49,006 --> 00:04:54,275 has touched the lives of virtually every one in the field of Geotechnical Engineering 54 00:04:54,276 --> 00:05:00,130 Detail biographies and appreciations maybe found in the volumes 55 00:05:00,131 --> 00:05:05,990 “Judgment in Geotechnical Engineering, The Professional Legacy of Ralph B. Peck” 56 00:05:05,992 --> 00:05:12,450 and “The Art and Science of Geotechnical Engineering, A volume honoring Dr. Peck” 57 00:05:12,455 --> 00:05:19,627 Most of us, in our written works are contempt to deal with technical issues alone 58 00:05:19,628 --> 00:05:21,961 not so Dr. Peck 59 00:05:21,962 --> 00:05:26,475 In his writings, he has done some considerable effort 60 00:05:26,476 --> 00:05:30,588 to discuss the role of “judgment” in Geotechnical Engineering 61 00:05:30,589 --> 00:05:33,463 This is a recurrent theme of his publications 62 00:05:33,464 --> 00:05:37,600 particularly over the past twenty years and it emphasizes 63 00:05:37,601 --> 00:05:42,370 Dr. Peck’s overwriting commitment to advancing our profession 64 00:05:42,371 --> 00:05:48,720 “Judgment” what is it? How do you get it? How do you apply it? 65 00:05:48,721 --> 00:05:54,220 We’re very fortunate that Dr. Peck returns to this theme 66 00:05:54,221 --> 00:05:57,795 of “Engineering Judgment” in the 1st video in the series 67 00:05:57,798 --> 00:06:00,745 “Leaders of Geotechnical Engineering” 68 00:06:00,780 --> 00:06:04,010 Let us now listen to Dr. Ralph Peck 69 00:06:10,500 --> 00:06:11,730 Thank you [Norbert] 70 00:06:11,732 --> 00:06:17,580 Everybody agrees that an “engineer” should have good judgment 71 00:06:17,581 --> 00:06:25,350 Everybody agrees I think that, great “engineers” have been men of “exceptional” judgment 72 00:06:25,351 --> 00:06:28,315 Probably, people would have a hard time 73 00:06:28,316 --> 00:06:32,670 defining what they mean by the term “Engineering Judgment”? 74 00:06:32,671 --> 00:06:35,990 I’m not sure I can define it myself 75 00:06:35,992 --> 00:06:42,260 but I can give some inclines as to what might be involved 76 00:06:42,261 --> 00:06:49,650 The One thing, an engineer of judgment needs a “sense of proportion” 77 00:06:49,651 --> 00:06:53,321 A “sense of fitness of things” 78 00:06:53,322 --> 00:06:57,886 and not all the “engineers”, unfortunately have this 79 00:06:57,887 --> 00:07:00,435 Quite a few years ago, 80 00:07:00,436 --> 00:07:06,464 I was on the examining board for Structural Engineering in the state of Illinois 81 00:07:06,465 --> 00:07:10,015 The people who took these examinations 82 00:07:10,016 --> 00:07:14,406 were required to have graduated from an accredited school 83 00:07:14,407 --> 00:07:21,795 and who have had 6 years of practice under the guidance of a registered structural engineer 84 00:07:21,800 --> 00:07:26,999 So these were men who had already had some experience 85 00:07:27,000 --> 00:07:31,647 Part of the examination was called “general engineering knowledge” 86 00:07:31,648 --> 00:07:36,339 and I used to ask some questions that people 87 00:07:36,340 --> 00:07:41,345 thought of as being quite unfair perhaps and a bit off-beat 88 00:07:41,346 --> 00:07:43,980 I asked for example; 89 00:07:43,981 --> 00:07:47,460 “what is the span of the longest suspension bridge?” 90 00:07:47,461 --> 00:07:52,780 Out the time, the “Golden Gate” Bridge was the longest bridge 91 00:07:52,781 --> 00:07:54,295 it was 4200 feet [˜1280m] 92 00:07:54,296 --> 00:07:57,900 I would have been perfectly happy with any answer between 93 00:07:57,901 --> 00:07:59,950 3000 feet and say a mile [5280 feet] 94 00:07:59,951 --> 00:08:02,450 because that was the right order of magnitude 95 00:08:02,451 --> 00:08:05,875 But there when were men taking examination 96 00:08:05,876 --> 00:08:11,555 who said 300 feet or 8000 feet or 10’000 feet 97 00:08:11,556 --> 00:08:18,105 These men had “experience” in designing 98 00:08:18,110 --> 00:08:22,488 But if they had made a calculation 99 00:08:22,489 --> 00:08:27,351 could you really expect them to test it out for size 100 00:08:27,352 --> 00:08:32,141 to see if they had really got the right order of magnitude of things 101 00:08:32,142 --> 00:08:37,658 The man had many other shortcomings 102 00:08:37,660 --> 00:08:42,671 that might be a little more historical than numerical 103 00:08:42,672 --> 00:08:46,998 I asked for instance, some times about famous engineers 104 00:08:46,999 --> 00:08:53,450 or famous structures, to identify the “Quebec” Bridge for example 105 00:08:53,451 --> 00:08:57,846 The answers I got were range from 106 00:08:57,847 --> 00:08:59,755 world’s longest suspension bridge 107 00:08:59,756 --> 00:09:05,606 the bridge that fell down twice during construction, which is a correct answer 108 00:09:05,607 --> 00:09:11,150 A correct answer, because it has also longest cantilever spans 109 00:09:11,151 --> 00:09:16,520 But whole variety of answers had suggested that these men 110 00:09:16,521 --> 00:09:21,447 might have had “No Conception” as to the magnitude of a big bridge 111 00:09:21,448 --> 00:09:26,571 And sometime I asked a really absurd question like “How big is a column load?” 112 00:09:26,572 --> 00:09:30,283 On the face of it, that doesn’t make sense 113 00:09:30,284 --> 00:09:38,023 If I had noted down and said “How big is a column load for a 3 story structure?” 114 00:09:38,024 --> 00:09:41,480 that was a little easier to answer 115 00:09:41,482 --> 00:09:46,750 And sometimes, I would get answers like 20’000’000 pounds [˜9091 tons] 116 00:09:46,752 --> 00:09:51,235 Out of structural engineer, who have been working for 6 years 117 00:09:51,236 --> 00:09:55,545 thought that a column load from a 3 story building 118 00:09:55,546 --> 00:10:00,190 was wonder would be more suitable safer than “Empire state” building or a serious tower! 119 00:10:00,191 --> 00:10:04,186 That man certainly, lacks the “sense of proportion” 120 00:10:04,187 --> 00:10:11,580 How would he be able to judge the correctness of simple calculation 121 00:10:11,581 --> 00:10:14,475 if he had no feel for the size of things? 122 00:10:15,170 --> 00:10:18,165 Another important aspect of judgment 123 00:10:18,166 --> 00:10:21,722 is being able to select and solve the “right” problem 124 00:10:21,723 --> 00:10:24,429 Number of years ago 125 00:10:24,430 --> 00:10:30,782 a little town in southern Illinois had a nice new junior high school 126 00:10:30,783 --> 00:10:33,367 Two story school, they were very proud of 127 00:10:33,368 --> 00:10:36,507 it was rather long and narrow structure 128 00:10:36,508 --> 00:10:39,354 A long structure two classrooms wide 129 00:10:39,355 --> 00:10:43,229 unfortunately, after a year or so 130 00:10:43,230 --> 00:10:45,177 it began to crack up rather badly 131 00:10:45,178 --> 00:10:49,655 and it begins to tear itself apart 132 00:10:49,656 --> 00:10:52,150 School board was about to 133 00:10:52,151 --> 00:10:55,360 give a contract for “under pining” the building 134 00:10:55,369 --> 00:10:58,505 But before they committed themselves to this expensive 135 00:10:58,506 --> 00:11:02,855 operation, they decided to have one more look at the problem 136 00:11:02,856 --> 00:11:07,070 They asked the University of Illinois if somebody could come and help them 137 00:11:07,071 --> 00:11:10,865 at that time the head of the department, Prof. Huntington 138 00:11:10,866 --> 00:11:13,850 was well-know as an expert in building construction 139 00:11:13,851 --> 00:11:16,080 he said “Yes” he would come 140 00:11:16,081 --> 00:11:20,010 and he bring me to look after the underpinning side of the question 141 00:11:20,011 --> 00:11:23,830 When we looked at the building, we noticed some rather interesting things 142 00:11:23,831 --> 00:11:25,320 It was cracked up indeed 143 00:11:25,321 --> 00:11:27,785 but there were “No cracks” in the 1st story 144 00:11:27,786 --> 00:11:30,410 All the cracks were on the 2nd story 145 00:11:30,411 --> 00:11:33,445 There were hardly any cracks near the center of the building 146 00:11:33,446 --> 00:11:37,250 They were all concentrated out near the ends of the building 147 00:11:38,138 --> 00:11:40,806 Couldn’t have been a foundation failure 148 00:11:40,807 --> 00:11:43,112 because, nothing had happened at the 1st story 149 00:11:43,113 --> 00:11:48,513 But much more likely, and certainly the cause of the problem here 150 00:11:48,514 --> 00:11:53,723 was “thermal effects” on the roof, which was reinforced concrete 151 00:11:53,724 --> 00:11:56,607 As the roof expanded and contracted in this long building 152 00:11:56,698 --> 00:11:59,339 it pushed the end walls out, pulled them back 153 00:11:59,340 --> 00:12:05,102 it pushed the columns between the windows to and through and develop cracks 154 00:12:05,103 --> 00:12:07,304 of course it didn’t cracked near the middle of the building 155 00:12:07,305 --> 00:12:11,133 because there, the total movements were small as in the center of things 156 00:12:11,134 --> 00:12:15,849 So the problem that was being looked at 157 00:12:15,850 --> 00:12:18,519 the problem, for which people would have spent a lot of money 158 00:12:18,520 --> 00:12:22,766 was the “wrong” problem 159 00:12:22,767 --> 00:12:25,879 The problem was in the “roof” not in the “foundation” 160 00:12:25,880 --> 00:12:28,580 The “engineer” who recommended underpinning 161 00:12:28,582 --> 00:12:31,110 somehow had missed that point 162 00:12:31,111 --> 00:12:34,137 He was solving the wrong problem 163 00:12:34,990 --> 00:12:37,958 Another similar example, a little more complicated perhaps 164 00:12:37,959 --> 00:12:41,518 occurred in connection with a vertical lift-bridge 165 00:12:41,519 --> 00:12:44,129 for the rail road in the city of Cleveland 166 00:12:46,470 --> 00:12:50,528 The bridge was being built for the rail road by another agency 167 00:12:50,529 --> 00:12:53,570 And the rail road was quite understandably 168 00:12:53,571 --> 00:12:57,057 being quite sure that they got a good job 169 00:12:59,050 --> 00:13:03,140 Vertical lift-bridge consists of a span 170 00:13:03,141 --> 00:13:07,836 that is raised like an elevator between 2 tall towers 171 00:13:07,837 --> 00:13:12,666 When the ship comes down the river, the lift span is raised 172 00:13:12,667 --> 00:13:16,299 ship goes under it and then the span comes back down together 173 00:13:16,300 --> 00:13:21,942 Rail road was very concerned about the settlements of the foundation 174 00:13:21,943 --> 00:13:25,662 they were concerned because they felt if the foundation is tilted 175 00:13:25,663 --> 00:13:28,676 then the span will change 176 00:13:28,677 --> 00:13:33,850 and the lift span itself might not be long enough 177 00:13:33,853 --> 00:13:36,373 for worse still if the pan span shortened 178 00:13:36,374 --> 00:13:39,837 if the towers tilted toward each other 179 00:13:39,838 --> 00:13:42,352 span might get stuck somewhere 180 00:13:43,165 --> 00:13:47,806 So the criterion was set up that the foundation settlements 181 00:13:47,807 --> 00:13:51,257 differentially couldn’t exceed ¾ of an inch [˜19mm]. 182 00:13:51,258 --> 00:13:57,042 There were some 300 feet [˜90m] of clay beneath the structure 183 00:13:57,043 --> 00:14:03,500 and the only foundations for which one could make a settlement calculation 184 00:14:03,625 --> 00:14:06,293 that indicated less than ¾ of an inch settlement 185 00:14:06,294 --> 00:14:10,085 would be deep piers extending all away to rock 186 00:14:10,938 --> 00:14:17,899 But at that time, piers to rock at that depth were unpersonated 187 00:14:17,900 --> 00:14:21,254 It would have been expensive and perhaps a risky operation. 188 00:14:21,255 --> 00:14:23,478 Friction pile foundations 189 00:14:23,479 --> 00:14:26,518 would have indicated the settlement of perhaps about an inch [˜25mm] 190 00:14:26,519 --> 00:14:29,951 which didn’t seem to be all that much more than ¾ of an inch 191 00:14:29,952 --> 00:14:32,404 But matters were at an impasse 192 00:14:32,405 --> 00:14:35,045 and there was a meeting between all the parties concerned 193 00:14:35,046 --> 00:14:39,767 At the meeting fortunately, was invited a consulting engineer 194 00:14:39,768 --> 00:14:43,320 whose whole life time practically, had been involved 195 00:14:43,321 --> 00:14:46,582 in the design and supervision of erection and maintenance 196 00:14:46,583 --> 00:14:48,563 of vertical lift spans 197 00:14:48,564 --> 00:14:52,757 When he listened to the discussion, he was asked for his opinion 198 00:14:52,758 --> 00:14:54,910 he smiled quite broadly 199 00:14:54,911 --> 00:14:58,625 he said “You know we always allow about 3 inches play ... 200 00:14:58,626 --> 00:15:01,558 at each end of our lift spans 201 00:15:01,559 --> 00:15:04,902 we can’t erect the tower that’s vertical 202 00:15:04,903 --> 00:15:08,320 when we are erecting steel tower and the sun comes up in the East 203 00:15:08,321 --> 00:15:10,850 and goes around to the South and then goes to the West 204 00:15:10,851 --> 00:15:12,827 the tower twists around it and moves 205 00:15:12,828 --> 00:15:14,899 we have to make allowance for that 206 00:15:14,900 --> 00:15:21,342 a ¾ of an inch is much too rigid a criterion” 207 00:15:22,100 --> 00:15:24,960 Again “the wrong” problem was being looked at 208 00:15:24,960 --> 00:15:30,800 A solution would have been devised that produced a very expensive foundation 209 00:15:30,801 --> 00:15:35,130 that would have really nothing to do with the critical mum thing 210 00:15:35,131 --> 00:15:37,050 the movements of tower 211 00:15:38,375 --> 00:15:43,195 A third aspect of judgment is the “ability to establish reasonable criteria” 212 00:15:44,900 --> 00:15:48,390 Sometimes, the unreasonableness comes about 213 00:15:48,391 --> 00:15:51,390 because of different disciplines involved in the same problem 214 00:15:51,391 --> 00:15:57,400 Number of years ago, the telephone company 215 00:15:57,405 --> 00:16:00,562 was extending its microwave system across the country 216 00:16:00,563 --> 00:16:03,875 with a series of microwave towers 217 00:16:03,876 --> 00:16:05,415 From each tower 218 00:16:05,416 --> 00:16:08,370 there was an antenna that broadcast signals to the next one 219 00:16:08,371 --> 00:16:12,359 where was picked up and amplified and passed on 220 00:16:21,953 --> 00:16:27,925 Again ¾ of an inch across the width of the towers; seems reasonable 221 00:16:14,820 --> 00:16:21,952 The telephone company sets some criteria for tilt of the towers 222 00:16:27,926 --> 00:16:31,443 but sometimes it was very difficult to achieve this criterion 223 00:16:31,444 --> 00:16:34,057 where the soil conditions were difficult 224 00:16:34,058 --> 00:16:39,442 Spacing of the towers and their location was pretty carefully defined 225 00:16:39,443 --> 00:16:44,410 because of other constrains such as mountains on the way, 226 00:16:44,411 --> 00:16:48,846 buildings on the way, minimum distances and so on 227 00:16:48,847 --> 00:16:53,584 So that the settlement criterion quite often came to be a ruling one 228 00:16:55,145 --> 00:16:59,966 As we began to discuss this matter with the electronics people 229 00:16:59,967 --> 00:17:02,961 who had worked on the wave guidance system 230 00:17:04,430 --> 00:17:07,127 finally, the top man came in to the picture 231 00:17:07,128 --> 00:17:11,523 and he said “I don’t know where that criterion came from ... 232 00:17:11,524 --> 00:17:16,185 We spread our signals over a much bigger area than the tower occupies 233 00:17:16,186 --> 00:17:20,000 If the tower moved a foot or so we still will pick up the signal 234 00:17:20,005 --> 00:17:22,677 It wouldn’t be a loss; it wouldn’t be a serious matter.” 235 00:17:22,678 --> 00:17:26,860 This immediately of course simplified the design of foundations 236 00:17:26,862 --> 00:17:28,175 and saved a lot of money 237 00:17:28,176 --> 00:17:31,347 But somebody somewhere along the line originally 238 00:17:31,348 --> 00:17:35,129 had set an unrealistic criterion and from then on 239 00:17:35,130 --> 00:17:39,604 matters became difficult and expensive for that reason 240 00:17:40,300 --> 00:17:45,305 What then are the bases for “Engineering Judgment?” 241 00:17:45,306 --> 00:17:48,008 What is a judgment founded on? 242 00:17:48,009 --> 00:17:52,173 There are probably two important ones 243 00:17:52,174 --> 00:17:56,451 One is “empiricism” or “precedent” 244 00:17:56,452 --> 00:17:58,321 What is worked in the past? 245 00:17:58,322 --> 00:18:01,593 A “good” engineer knows what is worked in the past 246 00:18:01,594 --> 00:18:04,521 He also knows what is not worked in the past 247 00:18:04,522 --> 00:18:12,120 That means he must be familiar with history of his field of engineering 248 00:18:14,190 --> 00:18:17,318 Empiricism saves people from making many mistakes 249 00:18:17,319 --> 00:18:19,900 But of course if we design things only 250 00:18:19,901 --> 00:18:21,740 in accordance of what have been done in the past 251 00:18:21,741 --> 00:18:23,547 we wouldn’t make any progress! 252 00:18:23,548 --> 00:18:27,338 So we have to go beyond precedence sometimes 253 00:18:27,339 --> 00:18:30,565 in designing our structures, our foundations, 254 00:18:30,566 --> 00:18:32,620 our engineering works 255 00:18:32,621 --> 00:18:37,868 and empiricism can’t be pushed too far in that direction 256 00:18:37,869 --> 00:18:43,288 For example, back in the early part of the century 257 00:18:43,289 --> 00:18:48,405 spans of suspension bridges were increasing almost year by year 258 00:18:48,406 --> 00:18:54,059 they went from 1500 feet [˜457m] to 2000 feet [˜610m] to 2500 feet [˜762m] 259 00:18:54,060 --> 00:18:57,022 and eventually of course up to 4200 feet [˜1280m] 260 00:18:59,200 --> 00:19:04,158 The builders, the designers of the Tacoma Narrows Bridge 261 00:19:04,159 --> 00:19:09,994 had a span that was within the realm of experience 262 00:19:09,995 --> 00:19:14,428 they did not realize that there was another factor 263 00:19:14,429 --> 00:19:18,687 that entered in the stability of the suspension bridge besides the “span” 264 00:19:18,688 --> 00:19:23,463 That was the “ratio of span to the depth of stiffening girder” 265 00:19:23,464 --> 00:19:29,298 Although the span of Tacoma Narrows Bridge was 2800 feet, 266 00:19:29,299 --> 00:19:32,661 only 2/3 that of the Golden Gate 267 00:19:32,662 --> 00:19:37,338 its ratio of span to depth was about twice that of Golden Gate 268 00:19:37,339 --> 00:19:40,487 How far that matter of any other suspension bridge? 269 00:19:40,488 --> 00:19:45,657 So following precedent with respect only to span 270 00:19:45,658 --> 00:19:48,580 led to the disaster that you all know about 271 00:19:48,581 --> 00:19:51,508 The bridge tore itself down in a wind storm 272 00:21:15,894 --> 00:21:21,895 Sometimes seemingly small extrapolations from precedent 273 00:21:21,896 --> 00:21:23,489 have also led to disaster 274 00:21:24,590 --> 00:21:27,486 The builders of Great Medieval Cathedrals 275 00:21:27,487 --> 00:21:30,999 kept building structures of higher and higher vaults 276 00:21:31,000 --> 00:21:36,262 As we can see by the sketch drawn by A. W. Skempton in the 1950s; 277 00:21:36,263 --> 00:21:40,135 Rheims 12% higher than Chartres, 278 00:21:40,136 --> 00:21:43,756 Amiens 13% higher than Rheims 279 00:21:43,757 --> 00:21:48,678 but when Beauvais attempted only 10% higher than Amiens 280 00:21:48,679 --> 00:21:54,041 it proved to be too far beyond precedent and collapsed disastrously 281 00:21:54,042 --> 00:21:58,550 It was finally rebuilt to a much lower height. 282 00:21:59,373 --> 00:22:02,836 Here again, the designers of that time 283 00:22:02,837 --> 00:22:06,245 followed precedent extrapolated a bit 284 00:22:06,246 --> 00:22:09,693 but they couldn’t tell how far they dared extrapolate 285 00:22:09,694 --> 00:22:11,363 and sometimes they overshot 286 00:22:12,188 --> 00:22:16,344 So the empirical basis for judgment 287 00:22:16,345 --> 00:22:19,087 is important but cares so many so far 288 00:22:19,088 --> 00:22:23,100 There is another basis, is the “theoretical” basis 289 00:22:24,133 --> 00:22:30,286 Theory also has its limitations but it gives us a feel for things 290 00:22:31,545 --> 00:22:35,300 I remember this, I suppose when I was in Chicago 291 00:22:35,301 --> 00:22:39,000 working on the subway project there 292 00:22:39,001 --> 00:22:43,835 Karl Terzaghi was writing his book on “Theoretical Soil Mechanics” 293 00:22:43,836 --> 00:22:48,000 One of my best friends in Chicago Al Cummings 294 00:22:48,001 --> 00:22:51,594 was district manager for the Raymond Concrete Pile Company 295 00:22:51,595 --> 00:22:53,569 Very unusual man 296 00:22:53,570 --> 00:22:58,019 by day, he was an extremely persuasive pile sales man 297 00:22:58,020 --> 00:23:01,549 He could sale piles in almost any circumstances 298 00:23:01,550 --> 00:23:07,554 By night, he entertained himself by delving into theory, 299 00:23:07,555 --> 00:23:11,478 particularly theory of elasticity and theories applied to soil mechanics 300 00:23:11,479 --> 00:23:15,055 and he not only studied the theories and knew them 301 00:23:15,056 --> 00:23:21,243 but he corresponded vigorously with the people who were working in the theories of that time 302 00:23:21,244 --> 00:23:22,872 So Terzaghi knowing this 303 00:23:22,873 --> 00:23:27,288 asked Al to review the manuscript of “Theoretical Soil Mechanics” 304 00:23:27,289 --> 00:23:29,835 and since Al and I saw each other a lot, 305 00:23:29,836 --> 00:23:34,202 Al began to pass the manuscript to me and I red it also 306 00:23:34,203 --> 00:23:38,194 and soon Terzaghi found out about this and we both became his guinea pigs. 307 00:23:38,195 --> 00:23:43,290 I was never given any reputation as a theoretician 308 00:23:43,291 --> 00:23:45,295 and indeed I am not a theoretician 309 00:23:45,296 --> 00:23:48,035 But going through these theories, 310 00:23:48,036 --> 00:23:51,346 examining which ones were really applicable, 311 00:23:51,347 --> 00:23:54,034 on the what circumstances they were not applicable 312 00:23:54,035 --> 00:23:58,325 and seeing the relationships, the theoretical relationships 313 00:23:58,326 --> 00:24:00,232 among the variables had entered the problem 314 00:24:00,233 --> 00:24:05,100 turned out to be an important part of my background 315 00:24:05,101 --> 00:24:06,395 This is not something I use, 316 00:24:06,396 --> 00:24:10,108 I don’t make calculations on the theoretical basis very often 317 00:24:10,109 --> 00:24:11,710 But those relations are there 318 00:24:11,711 --> 00:24:16,646 There are in the background and they help “guide” judgment 319 00:24:16,647 --> 00:24:23,014 in areas where precedent is not a wise thing to use 320 00:24:24,797 --> 00:24:27,993 I suppose the question then comes 321 00:24:27,994 --> 00:24:32,201 how do we cultivate engineering judgment? or can not be cultivated? 322 00:24:32,202 --> 00:24:35,550 Some people are inclined of think you are born with it 323 00:24:35,566 --> 00:24:38,406 and you have it or you are not born with it and you don’t 324 00:24:38,407 --> 00:24:44,301 I think it can be cultivated and I think it even can be taught 325 00:24:46,200 --> 00:24:49,393 One way to cultivate it is to make a conscious effort 326 00:24:49,394 --> 00:24:51,567 to determine the size of things 327 00:24:51,568 --> 00:24:57,333 to see how very structures have been built what their dimensions are 328 00:24:57,334 --> 00:25:03,528 To know how deep is feasible to excavate a foundation and so forth 329 00:25:03,529 --> 00:25:05,936 This means to keep up with the literature. 330 00:25:05,937 --> 00:25:10,156 To have a good education and followed by reading literature 331 00:25:10,157 --> 00:25:14,286 is a very good step toward developing judgment 332 00:25:15,009 --> 00:25:20,036 A second thing that a young person can do to cultivate judgment 333 00:25:20,037 --> 00:25:22,941 is to plan his career 334 00:25:24,675 --> 00:25:34,255 To select jobs of different kinds in the 1st few years of that career 335 00:25:34,256 --> 00:25:37,380 if you are structural engineer for example 336 00:25:37,381 --> 00:25:42,456 it would be a good idea to have some experience in design 337 00:25:42,457 --> 00:25:46,829 It would be a good idea to have some experience in the fabrication of structures 338 00:25:46,830 --> 00:25:50,408 It would be a very good idea to have some experience in construction 339 00:25:50,409 --> 00:25:53,604 so you would find out what you could put the things together 340 00:25:53,605 --> 00:25:55,248 that had been designed. 341 00:25:56,005 --> 00:26:00,350 The most employers do not make it 342 00:26:00,351 --> 00:26:06,807 their highest priority to see that a young person gets a varied experience 343 00:26:06,808 --> 00:26:10,873 Many employers only do one thing for example they only design 344 00:26:10,874 --> 00:26:14,021 and they can’t put an employee on the construction 345 00:26:14,022 --> 00:26:18,763 and so if you are a person looking for a breed of experience 346 00:26:18,764 --> 00:26:21,500 I think you have to do it yourself 347 00:26:21,501 --> 00:26:24,765 you have to owe it to yourself to decide 348 00:26:24,766 --> 00:26:27,213 which kinds of experience you would like to get 349 00:26:27,214 --> 00:26:31,760 to change jobs occasionally until you get that breed of experience 350 00:26:31,761 --> 00:26:36,228 This involve a certain amount of scarify sometimes 351 00:26:36,229 --> 00:26:41,987 It means losing seniority in some firms, 352 00:26:41,988 --> 00:26:43,484 it means moving your family around, 353 00:26:43,485 --> 00:26:46,377 it means putting the kids in different schools not like 354 00:26:46,378 --> 00:26:51,320 but it is still very important thing to get that variety of experience 355 00:26:51,321 --> 00:26:56,050 which is an invaluable asset in building judgment. 356 00:26:56,970 --> 00:27:01,096 A very good way to cultivate judgment is to keep a notebook 357 00:27:02,400 --> 00:27:07,351 Terzaghi insisted on this when I first went to work on the Chicago subway 358 00:27:07,352 --> 00:27:11,923 He insisted that I write down everything I had done that day 359 00:27:11,924 --> 00:27:15,159 everything I had seen on the job 360 00:27:15,160 --> 00:27:20,500 every conversation I had that was of some technical interest. 361 00:27:20,501 --> 00:27:24,884 I was in and out of tunnel headings very often 362 00:27:24,885 --> 00:27:26,496 several headings a day quite often 363 00:27:26,497 --> 00:27:32,810 and I would come back to the Lab and seat down to write in my notebook. 364 00:27:32,811 --> 00:27:37,124 I would try to make sketch of what I had seen in the heading 365 00:27:37,125 --> 00:27:39,297 the bracing, how went together 366 00:27:39,298 --> 00:27:43,274 where the excavation was with respect to the bracing and alike 367 00:27:43,275 --> 00:27:45,238 and I would discover all too often 368 00:27:45,239 --> 00:27:47,158 that when I came back I couldn’t do it. 369 00:27:47,159 --> 00:27:49,407 I missed some particularly detail. 370 00:27:49,408 --> 00:27:51,538 I didn’t really know how things went together 371 00:27:51,539 --> 00:27:54,450 and then I have to go back to the heading and look. 372 00:27:54,451 --> 00:27:56,643 After I done that 2 or 3 times 373 00:27:56,644 --> 00:28:00,147 I began to learn how to look in the first place and remember 374 00:28:00,148 --> 00:28:03,780 and then come back and be able to make satisfactory sketches. 375 00:28:03,781 --> 00:28:07,150 The power of observations is greatly improved 376 00:28:07,151 --> 00:28:11,362 by this very simple operation of keeping a notebook. 377 00:28:11,363 --> 00:28:14,120 It’s something that one might do all his life 378 00:28:14,121 --> 00:28:17,384 but certainly should be doing as a young person 379 00:28:17,385 --> 00:28:25,572 until the ability is achieved to register what is seen with your eyes. 380 00:28:26,046 --> 00:28:30,334 Judgment I think can be taught in the classroom in many ways. 381 00:28:32,330 --> 00:28:34,575 The instructor if he has experience 382 00:28:34,576 --> 00:28:37,285 can certainly brings his experiences to his class 383 00:28:37,286 --> 00:28:38,917 and this is extremely valuable 384 00:28:38,918 --> 00:28:43,000 It helps student get an idea of the size of things 385 00:28:43,001 --> 00:28:45,643 and what is quite important in the profession 386 00:28:45,644 --> 00:28:48,062 A professor can also 387 00:28:48,063 --> 00:28:52,780 teach students to make back of the envelop calculations 388 00:28:52,781 --> 00:28:55,093 for more complex problems 389 00:28:55,094 --> 00:29:00,060 Not all instructors feel this way I am afraid, 390 00:29:00,061 --> 00:29:01,715 I think unfortunately. 391 00:29:01,716 --> 00:29:05,650 One of my colleagues at the University of Illinois 392 00:29:05,651 --> 00:29:09,897 has said for many years “if you can’t make a back of the envelop calculation 393 00:29:09,898 --> 00:29:14,550 to get a rough idea of what the situation is, what the important variables are 394 00:29:14,551 --> 00:29:18,200 you have no business even trying to do a finite element calculation” 395 00:29:18,201 --> 00:29:22,398 That “back of the envelop” calculation 396 00:29:22,399 --> 00:29:28,066 again gives one an idea of the size of things of the answer what to be 397 00:29:28,067 --> 00:29:31,450 and if somebody hasn’t had that experience 398 00:29:31,451 --> 00:29:35,241 and set something up with an elaborate computer program 399 00:29:35,242 --> 00:29:37,069 and gets so many numbers to look at, 400 00:29:37,070 --> 00:29:40,176 he has nothing to compare those numbers with 401 00:29:40,177 --> 00:29:43,275 He has no way of comparing this with reality; 402 00:29:43,276 --> 00:29:45,909 he has no way of looking at it in simple manner 403 00:29:45,910 --> 00:29:48,258 to see if it makes sense at all. 404 00:29:48,259 --> 00:29:52,608 And so the ability to make those back of the envelop calculations 405 00:29:52,609 --> 00:29:59,312 represents something that I believe every instructor should feel obliged to teach. 406 00:30:00,040 --> 00:30:02,742 One can of course and should study precedence. 407 00:30:04,387 --> 00:30:08,050 That goes on all ones life. 408 00:30:08,051 --> 00:30:11,005 One does this by reading the engineering periodicals; 409 00:30:11,008 --> 00:30:16,698 one does this by looking at advertisements in the engineering periodicals. 410 00:30:16,699 --> 00:30:19,014 To see what the latest equipments may be? 411 00:30:19,015 --> 00:30:21,052 How things are being done in the field? 412 00:30:21,053 --> 00:30:23,162 One needs to keep up in that way 413 00:30:23,163 --> 00:30:25,499 and that is the way to sharpen judgment. 414 00:30:27,000 --> 00:30:30,953 And another very valuable way of developing judgment 415 00:30:30,954 --> 00:30:34,138 is by what might be called “apprenticeship” 416 00:30:34,139 --> 00:30:38,767 This isn't quite the same kind of apprenticeship I had in mind 417 00:30:38,768 --> 00:30:43,013 when I was talking about changing jobs from one position to another 418 00:30:43,014 --> 00:30:47,135 This is learning from somebody with experience 419 00:30:47,136 --> 00:30:52,275 on a particular job to do a certain complicated thing 420 00:30:52,276 --> 00:30:58,164 For example the foundation of every dam differs form that of any other dam. 421 00:30:58,165 --> 00:31:03,099 If it’s a rock foundation, there are all sorts of things that can differ; 422 00:31:03,100 --> 00:31:07,737 the presence or absence of faults, weathered zones 423 00:31:07,738 --> 00:31:11,337 when the foundation consists of beds that are tilted, 424 00:31:11,338 --> 00:31:15,212 are flat lining, are irregular, 425 00:31:15,213 --> 00:31:17,703 whether the abutments have many steps, 426 00:31:17,704 --> 00:31:19,111 where they have overhangs, 427 00:31:19,112 --> 00:31:22,103 all these things are important if one is going to put an earth dam 428 00:31:22,104 --> 00:31:24,306 on top of such a foundation. 429 00:31:24,307 --> 00:31:29,652 It’s almost impossible to write specifications that cover all these variables. 430 00:31:29,653 --> 00:31:32,145 You can’t write specifications in advance, 431 00:31:32,146 --> 00:31:34,946 because usually the site has not been excavated, 432 00:31:34,947 --> 00:31:37,259 so you can’t see what the conditions are, 433 00:31:37,260 --> 00:31:39,073 until the construction started. 434 00:31:39,074 --> 00:31:43,346 And so if somebody insists on writing specifications there is probably, 435 00:31:43,347 --> 00:31:45,215 not going to fit the picture. 436 00:31:45,216 --> 00:31:47,572 What seems to work the best 437 00:31:47,573 --> 00:31:52,903 is for the designers, and experienced people come out at the appropriate time 438 00:31:52,904 --> 00:31:54,824 when the foundation is uncovered. 439 00:31:54,825 --> 00:31:59,233 Get together with the contactor’s man who is going to actually do the work. 440 00:31:59,234 --> 00:32:02,774 Get together with the resident engineer who is going to supervise him. 441 00:32:02,775 --> 00:32:05,500 And go for spot to spot 442 00:32:05,501 --> 00:32:08,680 on the foundation and decide how each 443 00:32:08,681 --> 00:32:11,711 of the things that were seen would be treated. 444 00:32:13,000 --> 00:32:17,169 All the people would come to an agreement after discussing these things 445 00:32:17,170 --> 00:32:19,663 and decide how the job should be done. 446 00:32:19,664 --> 00:32:22,118 And this is a form of apprenticeship 447 00:32:22,119 --> 00:32:27,108 because those who have the feel, the experience in many projects 448 00:32:27,109 --> 00:32:29,410 can be the persons to come around 449 00:32:29,411 --> 00:32:36,709 and educate the folks "on the job" as to the situation that requires remedy. 450 00:32:37,734 --> 00:32:41,561 So in these various ways one cultivates judgment; 451 00:32:41,562 --> 00:32:45,437 by studying precedence, by varying experience 452 00:32:45,438 --> 00:32:48,853 and even by studying the lives and biographies of 453 00:32:48,854 --> 00:32:51,979 famous engineers to see how they approached their problems. 454 00:32:51,980 --> 00:32:56,380 Judgment is I think an acquired trick, 455 00:32:56,381 --> 00:33:01,432 something that every engineer should have and can have if he works at it. 456 00:33:03,426 --> 00:33:04,827 Few years ago Dr. Peck, 457 00:33:04,828 --> 00:33:09,290 you gave a talk at the University of Val on “Nature in civil engineering” 458 00:33:09,291 --> 00:33:13,781 In the last few years we’ve seen a growth in the environmental issues 459 00:33:13,782 --> 00:33:16,419 and the involvement of Geotechnical Engineering. 460 00:33:16,420 --> 00:33:19,659 Would you like to give some idea 461 00:33:19,660 --> 00:33:21,900 of how you see Geotechnical Engineering will play 462 00:33:21,901 --> 00:33:25,280 an important part and addressing future environmental problems? 463 00:33:25,290 --> 00:33:32,287 I think Geotechnical Engineering is basic to most of the environmental issues. 464 00:33:34,267 --> 00:33:38,713 I think we should remember that a century or two ago, 465 00:33:38,714 --> 00:33:45,343 the great English water supply engineers 466 00:33:45,344 --> 00:33:50,540 who built water supply systems for cities in England 467 00:33:50,541 --> 00:33:56,445 and thereby ended the episodes of cholera 468 00:33:56,446 --> 00:34:01,742 and many other devastating plagues that occurred at that time. 469 00:34:01,743 --> 00:34:05,267 Those engineers were very farsighted; 470 00:34:05,268 --> 00:34:09,688 they insisted that sewers be built to go with the water supplies, 471 00:34:09,689 --> 00:34:14,254 because they recognized that the waste would be a serous problem. 472 00:34:14,255 --> 00:34:18,680 That combination of supplying pure water 473 00:34:18,681 --> 00:34:26,631 and taking away the water that has been contaminated 474 00:34:26,632 --> 00:34:33,509 goes very back to the roots of practice of civil engineering 475 00:34:33,510 --> 00:34:37,930 and it’s as important today as it was to them. 476 00:34:37,931 --> 00:34:41,657 Civil engineers have built facilities that have 477 00:34:41,658 --> 00:34:45,934 helped produce some of waste we have, no question about it 478 00:34:45,935 --> 00:34:53,564 But are the civil engineers who have the “know how” to handle much of the waste; 479 00:34:53,565 --> 00:34:58,547 to store it, to conduct it, to do whatever is necessary. 480 00:34:58,548 --> 00:35:04,189 And much of this is done by pounding, 481 00:35:04,190 --> 00:35:07,028 by injecting into the ground, 482 00:35:07,029 --> 00:35:16,678 by various activities that directly call on the services of the Geotechnical Engineer. 483 00:35:17,050 --> 00:35:20,787 Dr. Peck you are still as enthusiastic about engineering 484 00:35:20,788 --> 00:35:24,871 as when I first met you at the University of Illinois over 30 years ago 485 00:35:24,872 --> 00:35:28,973 would you like to explain why your interests still so keen? 486 00:35:28,974 --> 00:35:33,025 I was enthused about being an engineer before I became one. 487 00:35:33,026 --> 00:35:34,896 My father was one, 488 00:35:34,897 --> 00:35:38,202 he was rail road bridge engineer in Colorado 489 00:35:38,203 --> 00:35:41,036 he enjoyed what he was doing, 490 00:35:41,037 --> 00:35:43,014 I wanted to do what he was doing, 491 00:35:43,015 --> 00:35:45,144 I wanted to be a bridge engineer, 492 00:35:45,145 --> 00:35:47,286 I got started down that road, 493 00:35:47,287 --> 00:35:49,554 and then I got deflected into 494 00:35:49,555 --> 00:35:53,246 what then was a newer branch of Geotechnics 495 00:35:53,247 --> 00:35:58,998 Everything that was done on those early days was new 496 00:35:58,999 --> 00:36:00,600 it was different 497 00:36:00,601 --> 00:36:07,005 and everything is being done today is likely to be bigger 498 00:36:07,006 --> 00:36:08,610 different, and better. 499 00:36:08,611 --> 00:36:12,479 I can’t imagine not being involved in engineering. 500 00:36:12,480 --> 00:36:16,404 I suppose one reason for why I enjoy it is that 501 00:36:16,405 --> 00:36:19,341 I can do “real” engineering. 502 00:36:19,342 --> 00:36:23,995 That is perhaps all that I tried to do, 503 00:36:23,996 --> 00:36:28,250 I don’t have to be running an organization, 504 00:36:28,251 --> 00:36:31,500 I don’t have to feed many mouths, 505 00:36:31,501 --> 00:36:37,239 I can pay attention to jobs that intrigue me because they’re different, 506 00:36:37,240 --> 00:36:39,883 because they have some sort of challenge. 507 00:36:39,884 --> 00:36:43,802 I think life without such a challenge would be pretty dull, 508 00:36:43,803 --> 00:36:47,891 and engineering is the thing I most like to do. 509 00:36:47,892 --> 00:36:50,000 I see no reason to stop it.