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Appends C
Data Collection and Compilation Procedures
The first step in planning for data collection was to design a form that
could be used somewhat like a questionnaire. Pertinent questions were
recorded and subdivided into appropriate categories, and blank space was
provided for answers. The 15-page form, presented at the end of this
Appendix, became the basic case history record of all data collected for
each project studied and provided the information extracted for the data
matrixes, abstracts, and computer retrieval system.
While the form was being designed, a list was made of all mined tun-
nel projects known to subcommittee members that appeared to meet the
study's needs. The list also included the names of agencies/owners
likely to have undertaken projects of possible interest to the subcom-
mittee. The basic criterion was that the project be a mined tunnel,
preferably not so new that pending litigation would preclude writing
about it and preferably constructed during the last 20 years, because
changing technology and difficulty of resurrecting records would other-
wise make it less applicable to drawing conclusions about modern tunnels.
Several hundred tunnels were considered in the process of selection.
The first step in actual data collection was to contact each owner
firm, requesting that a basic data package for each tunnel project be
provided to the subcommittee. When no specific tunnel had been~selected,
the owner was asked to make the decision and volunteer any projects
that seemed most appropriate. The basic data packages were to consist
of the following: contract drawings, specif ications, geotechnical re-
ports, bid abstracts or tabulations (including the Engineer's estimate),
and any other easily obtained documents considered of interest (often
including construction history reports and technical papers).
Meanwhile, Schnabel Engineering Associates of Bethesda, Maryland,
was retained as the engineering subcontractor for data extraction. The
firm's project manager and his assistant were briefed by the subcommit-
tee's senior consultant on the procedures to be followed and the termi-
nology to be used. (Examples of completed data forms were available for
two projects volunteered by the Washington Metropolitan Area Transit
Authority. ~ The need to achieve consistency in recording information
from projects from around the country was emphasized as being of prime
importance.
When the data packages arrived, they were turned over to the engi-
neering subcontractor. All of the packages from any particular owner
were assigned to a single staff member for data extraction; this proce-
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cure saved time and achieved consistency in answering questions. In ad-
dition, each of the subcontractor's six to eight staff members slated to
extract the data had been thoroughly briefed on the proper way of re-
cording answers to questions, so that consistency was achieved in the
way information was transcribed from project to project. Further, all
data forms were reviewed by the subcontractor's project manager and the
subcommittee's senior consultant, which allowed revision of any answers
that did not follow the established approach.
Using the basic data packages, the subcontractor was able to fill
out each 15-page data form to approximately the 40 percent stage of com-
pletion. This percentage varied from project to project because some
packages were more complete than others. Also, if a partially completed
data form had been received from a volunteer (owner, contractor, consul-
tant, subcommittee member), the amount of information available at this
stage increased considerably. It should be noted that the subcontractor
used only factual data from the volunteered forms, leaving the clarifi-
cation of subjective and interpretive answers to a later stage of the
study.
The 40 percent complete data forms were then assigned to interview-
ers who were to complete them to the 90 to 100 percent level by dealing
directly with owners and contractors. Interviewers were assigned from
the ranks of subcommittee members, the senior consultant, and the sub-
contractor for data extraction. In a few instances, interview assign-
ments were made to other interested individuals having the proper back-
ground.
Consistency among answers acquired by the interviewers was achieved
by several means. First, the interviewers were thoroughly briefed on
the proper approach to transcribing information. Second, a single in-
terviewer handled all the projects supplied by a particular owner. In
addition, that interviewer was expected to acquire information from both
the owner and the contractor (and from designers and geotechnical engi-
neers, if necessary). Thus, all projects supplied by a particular
source were generally written up by a single individual who had acquired
the most familiarity with that source's philosophy of geotechnical in-
vestigation, design, and construction. AS a final check on consistency,
the completed data forms were reviewed and often revised by the senior
consultant and by the subcontractor as a prelude to the next stage, the
creation of a project abstract.
In completing a data form to approximately 100 percent, an inter-
viewer was expected to combine answers from the owner, the contractor,
the 40 percent stage forms, and sometimes the volunteered data forms.
In general, most of the information to be collected during the interview
stage could be acquired from the owner; personal interviews were usually
required to check detailed records and to guide direction of the infor-
mation flow. Several pages of answers could be provided only by con-
tractors, and this could often be accomplished through an interview by
mail. To report fully on the projects, various combinations of the fol-
lowing individuals were interviewed: owners, construction managers,
contractors, designers, and geotechnical engineers. For some questions,
all principals were asked to reply and it was the interviewer's task to
sort through the different responses.
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When the 15-page data forms were essentially complete, they were re-
turned to the senior consultant or the subcontractor for reduction into
a two-page project abstract designed by the subcommittee. It was during
this stage that the forms were checked again for consistency and pol-
ished through follow-up telephone discussions with interviewers and
original suppliers of information. The two-page abstracts, which pre-
sent most of the hard, basic data that the reader will wish to review,
are printed in Volume 2 of this report.
Just as each abstract is a first stage in the reduction of informa-
tion from the data forms, the matrix presented in the text is the final
stage in which both original and extrapolated data from all the projects
can be compared in summary form. The matrix was designed and compiled
by subcommittee member Don C. Rose, as part of his task in data analysis.
He and another subcommittee member, Howard J. Handewith, used the matrix
as the basis for preparing graphs, charts, and curves showing relation-
ships between various aspects of each project. These were major tools
used by the subcommittee in analyzing and interpreting the mass of col-
lected data.
A parallel effort in analysis was conducted by G. Wayne Clough and
his students at Virginia Polytechnic Institute and State University.
Dr. Clough served as the subcontractor for computer programming/
processing and created printouts for each project, somewhat in the form
of the subcommittee's abstract but in greater detail and with more ex-
trapolated information. The computer was able to quickly re-sort and
tabulate the various data according to the key parameters chosen by the
analyzer. The final objective of the computer research was to develop a
data retrieval system that would allow management of the tunneling in-
formation compiled from the case histories. A description of the system
and examples of its capabilities are presented in Volume 2.
DATA COLLECTION PROBLEMS AND EXPLANATIONS
As might be expected in a project of this magnitude, problems in data
collection developed that cause some of the forms to be somewhat incom-
plete or not quite consistent with other forms. Many of the problems
will become apparent from a review of the data form presented herein and
the abstracts (Volume 2~. However, other problems are less obvious, and
the discussion that follows is intended to illustrate their nature.
0 The emphasis on "changed conditions claims as a yardstick for
measuring construction problems and cost overruns had to be changed when
it became apparent that many cost overruns are recorded as contract mod-
ifications, even when the initial request for payment is in the form of
a claim or results in the initiation of litigation. A different method
of tabulating the information was formulated, which is indicated by the
following note appended to each data form:
"Cost overrun tabulations make repeated refer-
ences to claims, claimed conditions, differing
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site conditions, disputes, litigation, and set-
tlements. In actuality, the figures are meant
to include all construction cost overruns caused
by unexpected geological/subsurface conditions,
whether pursued as claims/disputes or executed
as mutually agreeable contract modifications.
Where such overruns have failed to be included,
it is due to the difficulty of sorting out and
fully understanding legal/financial matters of
some complexity.
The terminology problem was avoided in designing the abstract
format. Nevertheless, the reader must remember that the word "claim"
(which appears in the data form and recurs frequently in the text of the
report) often may encompass many problems and/ or cost overruns that ap-
pear in owners' records as "contract modifications. "
· Records for older projects, as well as for some more recent
projects, were sometimes difficult to locate or impossible to obtain
because they had either been warehoused in a manner that discouraged
file searching, or destroyed. For newer projects, the difficulty in lo-
cating information generally was due to poor recordkeeping. It appears
that agencies involved in a "one shot" construction program are much
less likely to keep records than are agencies that build tunnel after
tunnel. The latter obviously have a need to build on past experience,
yet even their records were not always readily available for reference.
· Cost figures were not always available because some owners have
an unbreakable policy of not releasing any cost figures. Final costs
could not be obtained for projects under construction or for completed
projects with continuing litigation over changed conditions claims.
· Mined tunnel costs are rarely tabulated separately by owners,
either as estimated or bid, and therefore the cost had to be determined
by selecting the proper tunnel bid items from the total project bid
items. The project items to be included under mined tunnels were always
discussed and agreed upon among the subcommittee, senior consultant, and
subcontractor. Therefore, any possible errors in assumptions are prob-
ably reflected consistently in every project.
· Apportioning mobilization/demobilization percentages and com-
puting final costs for mined tunnels were judgmental procedures. Choos-
ing the percentage to apply to the mined tunnel and the percentage to
relegate to the remainder of the project was often accomplished in con-
sultation with owners and contractors, in order to ensure a reasonable
probability of assigning realistic percentages. Computing final mined
tunnel costs required judgments because final payments, contract modifi-
cations, underruns, overruns, changed conditions, etc., are not cate-
gorized or tabulated as neatly as estimates and bids. Even though con-
siderable effort was devoted to determining and properly assigning such
payments, the final reported mined tunnel costs may not be as accurate
as the estimates and low bids.
· Subsurface investigation costs were not available in most cases
because separate records for payments to drilling contractors, testing
laboratories, etc., were not maintained. When these costs were
available, it was difficult and sometimes impossible to apportion the
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correct percentage to the project under discussion because many investi-
gations overlap several projects. The most reliable of the site inves-
tigation costs reported pertain to the six WMATA projects, because the
owner volunteered a large number of staff and consultant hours to
searching files and apportioning the dollars appropriately.
· Cost escalation factors were not applied to the data forms or
abstracts. Escalation factors were determined for construction costs,
but not until the study was too far advanced to permit revising the data
forms and abstracts; reliable escalation factors could not be developed
for site investigation costs. Therefore, construction costs are pre-
sented as they appeared in the bid tabulations and pay vouchers; the
dollars represent the values for the years in which they were obligated
or paid. For site investigations also, the costs reported represent the
values for the years in which the monies were spent. In addition,
Canadian projects are always reported in Canadian dollars, and no
adjustments have been applied to make them directly comparable with U.S.
projects.
· The number of tabulated boreholes allows no differentiation for
clustering of boreholes or boreholes of limited usefulness. Consis-
tency required reporting all boreholes and drilling footages within a
reasonable lateral distance of the project being cited. Therefore, cer-
tain situations may be less obvious to the reader, such as: off-line
borings not directly applicable to final design/construction and hence
not tabulated, yet used by designers to understand the complete picture;
the percentage of boreholes with too shallow penetration to be of maxi-
mum usefulness; and boreholes clustered in certain areas while long
stretches of tunnel remained unexplored.
· Deep shafts require a different approach in order to under-
stand their nature and the meaning of the case history data. Deep
shafts generally are built for purposes other than those typical of
civil engineering and, as a result, procedures common to mined tunnel
projects are not always common to deep shafts. For example, deep shafts
may proceed through design and construction without performance of a
comprehensive site investigation, and many deep shaft projects are
acquired by contractors through a process of negotiation rather than
bidding. Also, for some deep mine shafts the process of renegotiation,
of give-and-take between owner and contractor, Nay continue as con-
struction proceeds. The reader should be aware of the differing aspects
of deep shaft and other underground construction projects, and also of
the resulting effects on the ability to collect detailed information on
shafts. The case histories for the three shafts studied will generally
be less complete than for the typical mined tunnel project.
As indicated in the foregoing discussion, the subcommittee's sources
of information included various combinations of contract documents,
technical papers, and interviews with owners, designers, contractors,
and geotechnical consultants. Design and site investigation answers
were relatively easy to determine, but comprehending the construction
history of a project was another matter altogether. Each individual
providing information had a unique perspective of a project, based on
interest, experience, expertise, and access to facts; this often re-
sulted in competing or contradictory responses to questions concerning a
particular project. Much of the ambiguity created by such responses was
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automatically cleared up in cases where a well-reasoned construction
history report had been compiled for the record, but such reports seem
to be the exception rather than the rule. The subcommittee recognized
the problems inherent in data collection and interpretation and took ad-
vantage of every opportunity to reduce or eliminate errors, thereby pre-
senting the most accurate case histories possible.
DESCRIPTION OF DATA = -
The 15-page data form included in this section was the basic means of
compiling and recording information on every project selected for study
as a case history. Many of the questions and information items are self-
explanatory, but others may be subject to interpretations that differ
from the subcommittee's intent. Therefore, this section is provided to
clarify any possible ambiguities. The items selected for explanation
are numbered as they appear in the data form.
I.1.
Length: means total gross linear feet of mining, not just length of
alignment (e.g., with twin tubes the tunnel mining length is generally
about twice the alignment length). In later headings the delineation
is made between footages in different types of ground and construction
methods. For shafts, the depth from the ground surface to bottom was
substituted. -
I.4.
B Line: used actual excavation line if no B line shown on plans.
Face Area: as computed using B line or actual excavation line.
I.5 e B.
Range of Depth: used ground surface to the tunnel crown (rather
than invert) because of ease in figuring from plans.
I.6.
Purpose_of Project: always supplemented with a footnote describing
non-mined tunnel items making up overall contract but generally not
considered in the study.
1.12.
Date of Design: mostly as taken from dates found on contract draw-
.
1ngse
1.13. & 14.
Dates of Construction Start and Completion: means dates for tunnel
mining, or shaft sinking, and installation of initial support (con-
sidered more useful than date of final lining completion).
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1.17.
Design Criteria, Water Pressure Indicated (Range): generally could
not be discovered, so mostly stated in terms of water head above crown.
IT.1.
Total Underground Construction Costs: modif fed to refer to mined
{or sunk, or raised, in the case of deep shafts) construction.
Involved judgments in choosing from the bid forms those items (or
percentage of individual item) that added up to the cost of excavating
and permanently supporting the opening. The cost of the total project
was included to help judge whether (and if so, how) bids may have been
unbalanced. All dollars {U.S. or Canadian) are unescalated and repre-
sent values for the year in which they were obligated or spent.
Claims: evolved into a statement of all construction cost overruns
caused by unexpected geological/subsurface conditions. Any overruns
not included were omitted due to oversight or misunderstanding .
II.3.
Site Exploration Time and Date: for prebid work, generally as esti-
mated from information on boring logs or taken from site investigation
reports.
lI.4.
Underground Construction Time, Scheduled: means calendar days for
excavation and installation of initial support.
III. -
Site Exploration: exceDt for a few items, a tabulation of all ure-
bid data development.
III.3.
Boreholes: includes only those along or close to the tunnel align-
ment (or shaft location).
III.7.
Water Table: range of depths below ground surface.
Head (Range2: depths from top of water table to tunnel crown (or
bottom of deep shaft).
Actual Inflow, Pressure, etc.: taken from construction records
where available (good information was rare).
IIIelO. ~ 11~, 12e
site Investication AdeauacY,
~ Improvability, Impact on Costs:
interviewer's subjective opinion, formed only after all data were con-
sidered and all principals with a viewpoint were consulted.
III.13.
Exploration Costs: information not available in most cases. When
it was available, an attempt was made to assign the correct percentage
of costs from wide ranging investigations to the mined tunnel (or
shaft) portion of the project under study.
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IV.10.-13.
Bidder/Contractor Actions and Attitudes: mostly available only
through an interview with the successful bidder. Answers were many
times unclear, especially if contractor's geotechnical consultant was
not available for comment.
VI.4.
Advance Rate: stated in ft per day, generally the manner in which
it is recorded by owners and contractors.
Minimum Advance Rate: stopped being reported because it always
turned out to be zero.
VI.5.
Problems: some overlap with VI.14., which describes circumstances
affecting progress of work.
Running Ground: may in many cases be a misidentification. The most
acceptable meaning for the term is of a cohesionless material above
the water table which runs from a tunnel face until a stable pile is
built up at the angle of repose. Below the water table, however, the
same material may be transformed into flowing ground, in which the
effects of seepage pressures toward the tunnel face create a flowing
mass that advances like a thick liquid into the heading. Such de-
scriptive accuracy is not always observed in the field and any
invading face material, whether dry or not, is often referred to as
"running" ground. The terminology was carried over from the inter-
views and ''as-built" reports and recorded in the data forms in order
to avoid second-guessing original sources. Hence, there are probably
some instances in which the forms refer to wet tunnel occurrences as
running ground when flowing ground would be a better description.
VII.
Litigation and Disputes Related to Geology: "litigation and dis-
putes" evolved into a statement of problems, including ones that the
owner immediately agreed were legitimate. "Geology" was expanded to
include subsurface conditions in general, in order to accommodate
situations such as buried piling (which is not truly geological but
should be reported in a good site investigation).
VII.1.-7.
Claims and Claimed Conditions : evolved into descriptions of all
construction extras requested, whether pursued as claims or executed
as mutually agreeable contract modifications. Any extras not included
were omitted due to oversight or misunderstanding.
VIII.
Other: used to comment on any significant facts not otherwise cov-
ered. The most common item is a description of operations and mainte-
nance problems in completed tunnels (the data for which was requested
by the Transportation Systems Center in Cambridge, Massachusetts).
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NATIONAL RESEARCH COUNCIL
COMMISSION ON ENGINEERING AND TECHNICAL SYSTEMS
2101 Constitution Avenue Washington, D. C. 20418
U. S. NATIONAL COMMITTEE
ON TUNNELING TECHNOLOGY
I . GENERAL INK ORMATION
GEOTECHNICAL SITE INVESTIGATION SUBCOMMITTEE PROJECT
Data Form
(202) 334-3136
1. Name of Project: Washington Metro Section A-9a, Contract lA0091*
2. Location: Northwest section of Washington D.C.
3. Shape: Circular Length: 7,620 ft for each of the
twin tubes = 15,240 ft
Grade: -3.5% to +3.23%
4. Diameter:
A Line = 18 ft 8 in.
B Line = 19 ft 1 in.
Face Area: 286 sq ft
5. Descr iption of Overburden:
A. Class if y by Rock or Soil Type:
gabbro gneiss, quartz-d~orite gneiss, chlorite schist, and
quartz-mica schist-to-gneiss. Overlain by decomposed rock
(saprolite) and man-made fill.
B. Range of Depth: 82 ft to 132 ft surface to crown.
C. Other:
6. Purpose of Project (water, power, transportation, etc.~: Running
tunnels for subway system. (Note: Contract also included 6
shafts, a tiebreaker station, and a pilot tunnel for a future pas-
senger station. Unless otherwise noted, data presented are for
running tunnels only.)
7. Owner: Washington Metropolitan Area Transit Authority
8. Designer : Parsons Associates {Ralph M. Parsons Company)
9. Construction Manager: Bechtel Associates
10 . Contractor: Mor riven-Knudsen and Associates
11. Geotechnical Engineer: Mueser, Rutledge, Johnston & DeSimone
Bedrock: interfinaerino
.
Note: For clarity in reading, the answers to the information items have been
typed rather than reproduced as originally handwritten. Therefore this ver-
sion of the data form is condensed to 10 neaes
_ , _
(excluding supplements} rather
than the original 15 pages noted in the text, because of the differential in
spacing required to accommodate handwriting as well as the longest answer ex-
pected to any item.
*The contract also included six shafts, a tiebreaker station, and a pilot tun-
nel for a future passenger station. Unless otherwise noted, data presented
are for running tunnels only.
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12. Date of Design: 1972 - 1974
13. Date of Construction Start: September 19, 1975
14. Date of Completion: November 8, 1976
. (excavation and temporary support only)
15. General Ground Conditions Indicated by Specifications: Foliated
to massive, jointed, somewhat sheared, moderately hard rock, suit-
able for either TBM or drill-and-blast mining.
16. Design Criteria, Range of Ground Loads Indicated: Unable to
determine.
17. Design Criteria, Water Pressure Indicated (range}: 70 to 103 ft
head of water above crown.
18. Computerized or Other Special Design Techniques Used (e.g., for
temporary and permanent supports, etc.~: Unable to determine.
19. Monitoring during Construction (ground movement, water flow, gas,
temperature, etch: Rock movements monitored with extensometers.
IT. PROJECT COSTS AND SCHEDULE
I. Total Underground Construction Cost (excavation, support, and
permanent lining):
A. Estimated: $25,362,500 excavation/support, running tunnels
$33,293,520 total contract
B. Bid: $24,993,500 excavation/support, running tunnels
$34,931,600 total contract
C.
As completed:
Including changes other than claims: $25,189,396
(running tunnels)
Claims: $1,975,350 {running tunnels)
D. Total (of C): $27,164,746 (running tunnels)
$36,950, 201 {total contract)
2. Site Exploration Costs (if reasonably available): For breakdown
of costs, refer to III, 13.
Prebid: $101,534 % of 1.D: 0.37
Post Award: % of 1.D:
Total: $101,534 % of 1.D: 0.37
3. Site Exploration Time and Date (prebid--field and office): 12
months in 3 programs between Apr it 1968 and Apr il 1973
Underground Construction Time:
Scheduled: 286 calendar days for mining and placing temporary
support in running tunnels
IIT. SITE EXPLORATION
1. Geologic Studies:
Literature search, regional (general description): Collection
of geologic and topographic maps and government geologic reports
Site {general description}: Rolling Piedmont landscape, urban
alignment beneath major thoroughfares
Surface mapping, ground types (rock/soil!: Only man-made fill
visible at surface.
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Rock/soil structure (general descr iption of folding, faulting
jointing, bedding, etc.) : Complex intruded metamorphics; schist-
ose portion having foliation subparallel to alignment; numerous
shear zones; at least 5 joint sets, 3 of them major.
ck/soil quality (hardness, weathering, consolidation, origin,
etc. ): Rock varying between 750 and 17, 600 psi compressive
strength. Upper portions weathered to depths as great as 60 ft.
but tunnel prof lie mostly below this weathered zone.
Cross sections (how many and what kind): One 7,620-ft detailed
geologic profile on scale of 1" = 80' horizontal by In = 20' ver-
tical.
Boreholes: Yes If yes, were they detailed? Yes
RQDs (were they provided?: Yes
Other classification systems (e.~., RSR, joint frequency):
Geophysical Studies: No
Type of seismic surveys (reflection, refraction, etc.~:
Surface resistivity:
Type of borehole logging (E-logs, temp., Gamma-ray, etc.)
Other: _
3. Boreholes--number: vertical 45
horizontal 0
inclined 4
Total 49
Diameter: Few 2-1/2"; mostly 3-1/2" with NX coring.
Total footage: 1,774 ft soil sampling; 4,348 ft rock
Maximum length: 162 ft
Minimum length: 24.3 ft
Location with respect to centerline: Generally no more than 40
ft away from centerline of one of the tunnels. However, one 1,600
ft stretch has 7 borings that are 60 to 155 ft away because they
were done for an earlier alignment alternative.
Average spacing along centerline: 169 ft
Borehole Tests: No
Permeability: 41 water pressure tests with packers, and 75 fal
ing head tests in borehbles and observation wells.
Water:
4.
Other: Borehole photography in 2 vertical borings.
In situ stress/deformability tests: No
5. Exploration on Pilot Tunnels/Shafts (describe how many, where,
lengths, etc.~: None
6. Construction History Studies of any Nearby Existing Tunnels and
Shaf ts (describe where, what data obtained): Detailed data col-
lected from Metro Section A-4a, an earlier drill-and-blast tunnel
about 2 miles downstation from the subject A-9a tunnels. In addi-
tion, the A-9a contractor had just built the adjoining 9,500 ft
long section, A-6a; he used the same TBM on both jobs.
Hydrology and Groundwater {describe water bearing layer and prop-
erties): Rock tunnel--no particular water bearing layer noted.
Water table: 70 to 103 ft above tunnel crown.
Porosity: Not noted .
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Permeability: Bedrock--low = 1.0 x 10 7 fpm; median = 1.8 x
10-4 fpm; high = 1.0 x 10-3 fpm (packer tests) .
Head (range): 70 to 103 ft at crown.
Prebid predicted inflow (maximum volume, length of time, and max-
imum pressure}: No predictions.
Prebid predicted minimum sustained inflow and pressure: No pre-
dictions .
Actual inflow (maximum volume, length of time, and maximum pres-
sure ): No records .
Actual minimum sustained inflow and pressure: No records.
Chemistry (fresh water , saline, etc. ): Fresh, high in dissolved
carbonate .
8. Laboratory Tests:
Strength: 7 5 unconf ined compr ess ion on rock; unconf ined compr es -
sion, triax~al compression, and direct shears on soil.
Hardness: None
Abrasion: None
Permeability: None
Density: Yes
Soil classification: Water contents, atterberg limits, grain
s i ze analys is
Dynamic properties:
.
Other: Few consolidation tests on soil.
9. Additional Laboratory Testing: Corrosion potential of soil and
water : pH and resistivity plus concentrations of sulfates (SO4),
chlor ides {C1), and carbonates (CO3 ~ .
10. Was Site Investigation and/or Interpretation Adequate to Prevent
"Surprises.? (interviewer's subjective opinion}: Probably not.
If the severe conditions were truly obvious from the 2 applicable
borings, then the owner would probably have sunk other borings to
confirm the conditions and map their extent.
11. Could Site Investigation and/or Interpretation Have Been Improved
or Modified? (interviewer's subjective opinion): Most likely.
However, the owner would have had to foresee the severe conditions
from the 2 applicable borings in the area, and then to sink addi-
tional ones in precisely the right spots to further define condi-
tions.
Would a Modified Investigation and/or Interpretation Have Had a
Significant Cost Impact on the Project? (interviewer's subjective
opinion}: A properly modified program would have had an impact.
With solid advance warning of the severity of conditions in the
one area, the contractor . could have taken precautions (such as
mining his "rescue" tunnel in advance of the mole's arrival at the
spot), thus avoiding considerable delay and saving money.
Breakdown of Exploration Costs (give amount and date):
Drill holes: Subprofessional = $47,146; professional - $24,362.
Mapping: $150
Geophysical: None
Other: Lab = $5,456; office = $24,420.
Total: $101, 534 in 1968 through 1973 pr ices.
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IV. BIDDING PERIOD
Number of Bidders: 3
Requirement for Prequalif ication: None
Were Bid Abstracts Available? Yes
Time Allowed for Bid Submission: 6 weeks originally. However,
an initial bid was rejected because 2 contractors failed to sign
minority participation clause, so job was rebid. The effective
bidding period was then 14 weeks.
5. What Subsurface Information was Provided in the Bid Package?
Maps: No--none compiled by Geotechnical consultant.
Bor ing logs: Yes--bound directly into contract drawings.
Other: Geotechnical reports with profiles and all test results.
(The reports were laid out for bidders' examination, and copies
could be bought from the National Technical Information Service.)
If provided, was detailed information set forth? Yes
6. What Geotechnical Data Were Made Part of the Contract Document?
Geotechnical reports: _ ,
Geophysical logs: No geophysical logs created.
See Question 5. above. If so. identify.
Core samples: Specifically listed as available for inspection on
24 hours notice.
Age of samples: Between ~ And ~ veers -
Condition of samples: _
Geologic mappings and cross sections: See question 5, above.
Test data: See question 5, above . If provided, describe:
Results of all f ield and lab testing on soil samples, rock cores,
boreholes, and observation wells.
Photo {display): No photos
Was there a prebid display room exhibiting photos, maps, other
documents, etc. (what did it consist of ~ ? Construction coordina-
tor 's office, where Geotechnical reports could be examined.
Other: Core shed, where geologic samples could be examined.
8. What {If Any) Geological Technological Information Possessed by
Owner Was Not Provided to Bidders? Gover nment geologic maps and
reports considered 3rd party information and not made available; it
was up to interested bidders to locate their own copies.
~ ~ ^ ~~ If so, were questions asked
Please describe the questions and
Soil dessicated: rock good.
9. was There a Preola conference: NO
re subsurface conditions?
answers: _
10. Did Any Bidders Obtain Their Own Expert Evaluation of Subsurface
Data, Particularly the Successful Bidder? Yes
(briefly describe it):
If so, identify
_ Consulting Geotechnical specialists inde-
pendently evaluated the rock core and the owner's Geotechnical re-
ports. Similar studies also carried out by three major TOM manu-
facturers.
11. Did Any Bidders Make an Independent Subsurface Investigation?
Not prior to bid award. If so, describe briefly:
12. What Subsurface Information Did Contractor Rely On in Prepar ing
His Bid? (Object is to discover what contractors rely most on):
Bor ing logs: Yes
Geophysical data:
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Core samples: Yes
Geotechnical reports: Yes
Geological mappings and cross sections: Yes
Other:
Explain why specific types of information were relied on by the
contractor and in order of importance: Relied on all quantified
data or documents; reviewed reports but did not necessarily rely on
judgments, evaluations, conclusions.
Explain why if any types of information were not relied on:
"Facts" were relied on; opinions, not necessarily.
Was there any specific type of data desired by the contractor but
not made available? None remembered by the individual who com-
pleted the prebid geologic evaluation.
What experience, if any, did the contractor have in comparable
underground construction work? 4 5 years in underground construc-
tion. Had just built the adjacent section in similar rock, using
the very same TBM.
V. CONTRACT FORMAT
Contract Format:
Lump sum:
Cost plus:
Other:
If unit price format was used, were estimated quantity variation
limits specified? 15% {plus or minus) without adjusting contract
price.
Was Differing Site Conditions Clause or Equivalent Included?
Yes, but see question 3, below.
Was there a changes clause or equivalent: Yes
If answers in 2 above were no, how was risk of changed conditions
dealt with contractually? Since rock was specifically excluded
from coverage under the changed conditions clause, the contractor
was expected to include sufficient contingency in his bid price to
cover any rock condition encountered.
3. Were There Disclaimers or Caveats on the Owner-Furnished Informa-
tion on Subsurface Conditions? {1) Note that data presented for
information only with no accuracy warranty. (2) Note that rock
not covered by changed conditions clause.
4. Provisions Re Schedule, Time of Completion:
for total contract. (The contractor was required to submit for ap-
proval a graphic network diagram [schedule] indicating construction
dates for various major features, which did include running tunnels
estimated at 286 calendar days for mining.)
Definition of delay: Yes {see Supplement 1~.
Definition of suspension of work: Yes (see Supplement 2~.
Liquidated damages clause: Maximum $5, 000 per day of delay.
Payment Provisions:
Monthly: Yes
Unit pr ice :
per ft of single track
tunnel
915 calendar days
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Retainage percent: 10%
Other : Payment related to progress (see Supplement 3~.
Pricing for Temporary Support (describe briefly): Details of
temporary support strictly the responsibility of the contractor,
with payment to be included in the overall contract unit price per
ft for "single track tunnel."
Construction Methods Specified:
TBM: Option*
Drill-and-blast: Option*
*Job des igned as either TBM or drill-and-blast, with contractors to
bid the option they preferred. Low bidder chose the TBM option.
Other:
8. Restr Actions:
Hours of work: None for TBM mined tunnel. Some shafts restrict-
ed to 7:00 a.m. to 10:00 p.m. or 8:00 a.m. to 6:00 p.~n.
Blasting: Permitted only from 7:00 a.m. to 10:00 p.m., Monday
through Saturday, and 2:00 p.m. to 10:00 p.m. on Sunday.
Hauling: No spec i f fed res frictions.
Other : Noise restrictions (dBA levels) for equipment in various
locations and hours of resident activities .
Disputes Resolving Provisions (i.e., arbitration, suit, etc. ):
To be decided by owner's contracting officer, whose decisions can
be appealed to owner ' s board of directors within 30 days. Board
decision final unless question is one of law that results in liti-
gation in court.
VI. CONSTRUCTION
2.
1. Type of Project:
Hard ground: Yes
Soft ground:
Mixed face:
Other:
Length of Work Week:
Days: 5
Why was this schedule used?
Number of Men:
Day: 20-22 men Swing: 20-22 men Graveyard: 20-22 men
3. Major Equipment Used: Robbins 191-161 tunnel boring machine.
Mucking and hauling: front end loaders, 25 ton locos, 16 cu yd
muck cars, rotary dump cranes.
4. Advance Rate (per day):
Maximum: 125 ft Minimum: 0 tt
Overall average (per day): 65 ft. good rock; 56 ft. poor rock.
Problems:
Excessive overbreak:
Poor ground stability: In one 650 ft long stretch only.
Cave-ins: in same 650 ft Running Ground: in same 650 ft
Groundwater: Gas:
Other:
Residual stresses/swelling/squeezing ground:
Shifts: 3
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7-
Special Conditions:
Utilizing compressed air: No
Subaqueous {under lakes, rivers, bays}: No
Twin bore: Yes; tunnels Dewatering problems: No
driven consecutively by
same TBM; required complete refurbishing between 1st and 2nd bores.
Lost 5 weeks from completion of 1st tunnel to start of the 2nd.
Grouting (for running ground or settlement): Yes, but it proved
ineffective and was quickly dropped.
Other:
Primary Support:
Steel sets (describe) : W6x20 on 4 ft centers in bad ground and
in portion through the future station location. (Note: Applies to
standard tunnel section. Shotcrete, longer rock bolts on different
patterns, heavier steel and thicker concrete used in cross edit and
shaft breakout areas.)
Rock bolts (describe): 6 ft bolts with wire mesh on 5 ft x 5 ft
in top arch used in 63% of tunnel length. (Applies to standard
tunnel section, as noted above.)
Shotcrete:
Other:
8. Final Linings (none, shotcrete , cast-in-place , segments , other ):
Reinforced cast-in-place concrete, 1 ft thick. This final lining
omitted in the 653 ft long section where a future station was to be
blasted out of the rock between the running tunnels and the pilot
drift. (Applies to standard tunnel section, as noted in 7, above.)
9. Excavation Equipment Manufacturer (TOM, roadheader, etc.~:
Model: Robbins 191-161 Diameter: 19 ft 1 in. (O.D.)
Weight: 285 tons Cutterhead power: 900 horsepower
Thrust: 1,850,000 lbs. Torque: 3,500,000 lbs.
Grippers: 2 horizontal Cutters: 45 (15-1/2 in. discs)
opposed
Down time: 18.1%
10. Shield (description): Not applicable
11. Ventilation (type and volume): Joy 48 in. fan line.
12. Mucking {descr ibe system): Endless belt to muck train par ked in-
s ide back of TBM. Muck hauled through Contract A-9a and Contract
A-6a (previous tunnel built by same contractor I, stockpiled at the
por tal and hauled away by tr uc k .
13. Were Changes in Design Made After Award Due to Unforeseen Geologic
Conditions? No
Was contract flexible enough to allow this? No, not without a
formal contract modif ication.
Other conditions:
14. Was Progress of Work Affected by Any of the Following:
Redesign: No
Contractor inexperience: No
Squeezing ground: No
Cave-in: In the one bad ground area there was a chimney to the
bottom of the street pavement.
Groundwater inflow: Yes, once. But the pocket of water in bad
ground drained within a few days.
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Fault zones: No
Other: Intensely weathered shear zones associated with a contact
zone between country rock and an intrusive.
15. Was a Contingency for Geologic Uncertainty Included in Bid? No
Could it have been reduced if more exploration had been made?
How much reduced?
16. Safety Record with Regard to Geologic Conditions: Miners ' claims
of damage by s ilica from the rock dust .
VI I . LITIGATION AND DISPUTES RELATED TO GEOLOGY
1. Were There Signif icant Claims by the Contractor ?
claim for $7 million.
2. Were There Signif icant Claims by Owner Against Contractor? No
Against engineers? No
If so, identify by brief description and amount in dollars:
3. If Contractor Claim Was Based on Differing Site Conditions, Please
Describe the Claimed Condition and How it Allegedly Differed:
The contractor encountered ground so bad that the mole became stuck
and efforts to turn the Butterhead resulted in flows of mud and
water into the tunnel, with some caving above the tunnel. The mole
fought its way through 300 ft of this ground but a top heading,
hand-mined "rescue" tunnel had to be driven from ahead to meet the
machine; a similar top heading was driven for 650 ft in the adja-
cent tube. These operations resulted in much extra work and tunnel
support and delays. The contractor claimed the problem was due to
unforeseeable deep weathering so bad that there were actually
"pendants" of saprolitic soil extending down into the rock tunnel.
What was the owner's position with respect to any such claims?
The owner's initial position was that the contractor had simply en-
countered intense weathering along a concentration of shear zones
so common in the area and quite predictable from contract document
information. The bad material was sheared and weathered rock and
not soil-like until the mole ground it up. The claim was thus
denied because rock was specifically excluded from changed condi-
tion provisions in the contract. However, during the early stages
of litigation, the owner conceded that the condition encountered
was unusually severe and agreed to the soil-like nature of some of
the material. This made it coverable by the changed condition pro-
visions and freed owner and contractor to negotiate an extra e
4. Were the Claims Settled? Yes
Short of arbitration board or litigation? Litigation began, but
settlement was achieved before it actually came to tr ial.
What percentage was recovered in settlement of the claims? 28%
(asked for $7 million and received $1,975,350~.
Was interest included in settlements? No
If Claims Were Arbitrated, Before What Panel? Not arbitrated
What result?
What percentage of claims was recovered?
What was the cost of arbitration?
How long did it take to get a decision?
Yes, one major
. . .
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6. If Claims Were Litigated, Before What Forum? Corps of Engineers
Board of Contract Appeals.
What result? Litigation proceeded through the pleading and dis-
covery stages, but the parties reached agreement on their own
before trial was actually begun.
What percentage of claims was recovered? 28% (see question 4
What was the cost of litigation? No information
How long did it take to get a decision? No decision; time frame
unknown for mutually agreeable settlement.
7. To What Extent Were Contractor Claims Asserted and Resolved Con-
temporaneously with Performance? Asserted during performance but
not resolved until several years later.
VIII. OTHER
Operations and Maintenance Problems: Trains are not yet running in
these particular tunnels, so the full extent of operations and maintenance
problems are not yet evident. There was (and still is) intrusion of diesel
fuel into the tunnel from a garage site spill. Although not serious enough to
be a safety hazard during or after construction, the oil does continue to seep
into the drainage system and to be concentrated at the nearest pumping station.
From here it is released into a small natural stream in sufficient concentra-
tion to be an environmental problem.
Calcium carbonates are creating the longest-term operations and mainte-
nance problems. The CaCO3 is picked up from calcite joint fillings in the
rock. Carried in fairly heavy concentrations in the groundwater, it precipi-
tates when pressure is released as the water emerges into open air inside the
tunnels. One-third of the hydrostatic pressure relief (HPR) pipes were
clogged by the time of tunnel acceptance, and perhaps three-quarters of them
are clogged by this time. The precipitates also clog drainage slots, lines,
and gratings, and probably any gravel filter blankets under the concrete in-
verts. They tend to form messy, slippery deposits that can be a hazard on the
safety walks.
It has proved practically impossible to ream the carbonates from the
small HPR pipes, but the drainage slots, lines, and gratings can be kept rela-
tively clean by periodic treatment with a rotary cleaning tool and high pres-
sure water. It is important to attack the deposits while they are still in a
gel state and not completely solidified. Testing the degree and speed of cal-
cification of the gravel filter blankets and then trying to stop or reverse it
is still an unsolved problem.
Interviewer
C.W. Daugherty
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Supplement 1
Washington Metro Section A-9a
1. 5 TERMINATION FOR DEFAULT - DAMAGES FOR DELAY - TIME EXTENSIONS
(a) If the Contractor refuses or fails to prosecute the work, or
any separable part thereof, with such diligence as will insure its
completion within the time specified in this contract, or any ex-
tension thereof, or fails to complete said work within such time,
the Authority may, by written notice to the Contractor, terminate
his right to proceed with the work or such part of the work as to
which there has been delay. In such event the Authority may take
over the work and prosecute the same to completion, by contract or
otherwise, and may take possession of and utilize in completing the
work such materials, appliances, and plant as may be on the site of
the work and necessary therefor. Whether or not the Contractor's
right to proceed with the work is terminated, he and his sureties
shall be liable for any damage to the Authority resulting from his
refusal or failure to complete the work in the specified time.
(d) The Contractor's right to proceed shall not be so terminated
nor the Contractor charged with resulting damage if:
(1} The delay in the completion of the work arises from un-
foreseeable causes beyond the control and without the fault or
negligence of the Contractor, including but not restricted to,
acts of God, acts of the public enemy, acts of the Authority
in its contractual capacity, acts of another contractor in the
performance of a contract with the Authority, fires, floods,
epidemics, quarantine restrictions, strikes, freight embar-
goes, unusually severe weather, or delays of subcontractors or
suppliers at any tier arising from causes other than normal
weather beyond the control and without the fault or negligence
of both the Contractor and such subcontractors or suppliers;
and
(2) The Contractor, within 10 days from the beginning of any
such delay (unless the Contracting Officer grants a further
period of time before the date of final payment under the con-
tract), notifies the Contracting Officer in writing of the
causes of delay. The Contracting Officer shall ascertain the
facts and the extent of the delay and extend the time for com-
pleting the work when, in his judgment, the findings of fact
justify such an extension, and his findings of fact shall be
final and conclusive on the parties, subject only to appeal as
provided in the "Disputes article of these General Provisions.
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Supplement 2
Washington Metro Section A-9a
1.38 SUSPENSION OF WORK
(a) The Contracting Officer may order the Contractor in wr iting to
suspend, delay, or interrupt all or any part of the work for such
period of time as he may determine to be appropr late for the con-
venience of the Authority.
(b) If the performance of all or any part of the work is, for an
unreasonable period of time, suspended, delayed, or interrupted by
an act of the Contracting Officer in the administration of this
contract, or by his failure to act within the time specified in
this contract (or if no time is specified, within a reasonable
time), an adjustment shall be made for any increase in the cost of
performance of this contract (excluding profit) necessarily caused
by such unreasonable suspension, delay, or interruption and the
contract modified in writing accordingly. However, no adjustment
shall be made under this article for any suspension, delay, or in-
terruption to the extent (1) that performance would have been so
suspended, delayed, or interrupted by any other cause, including
the fault or negligence of the Contractor or (2) for which an equi-
table adjustment is provided for or excluded under any other pro-
vision of this contract.
(c) No claim under this clause shall be allowed (1) for any costs
incurred more than 20 days before the Contractor shall have noti-
fied the Contracting Officer in writing of the act or failure to
act involved (but this requirement shall not apply as to a claim
resulting from a suspension order), and (2) unless the claim, in
an amount stated, is asserted in writing as soon as practicable
after the termination of such suspension, delay, or interruption,
but not later than the date of final payment under the contract.
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Supplement 3
Washington Metro Section A-9a
2 . 9 DETERMINATION OF PROGRESS
(a) Independent of progress payments made pursuant to Article 1.7,
Payments to Contractor, progress schedules prepared under the re-
quirements of Article 2.8, Progress Schedules - Network Analysis,
shall provide as schedules progress for only 50 percent of the esti-
mated invoiced cost of materials or equipment delivered to the site
but not incorporated in the work as of the time of the scheduled de-
livery thereof.
(b) In determining progress accomplished, the Engineer will allow
as an element of work accomplished (progress toward completion) only
50 percent of the invoiced cost of materials or equipment delivered
to the site but not incorporated in the construction up to the time
the materials or equipment are actually incorporated in the work.
148
Representative terms from entire chapter:
mined tunnel
