-
Chapter 35
THE ECONOMICS OF USED TUNNEL BORING MACHINES
By Victor J. Scaravilli, P.E.
PresidentS & M Constructors, Inc.
Solon, Ohio
This report is based on experience developed on the construction
ofone contract for the Buffalo, New York subway. The Buffalo subway
isunder construction for the Niagara Frontier Transportation
Authorityand is called the LRRT-Light Rail Rapid Transit or more
commonly theMetro. The Initial Route of the Buffalo subway
construction startedearly in 1979 and is scheduled for completion
in May, 1984. The ini-tial system includes 5.2 miles of underground
construction, 1.3 milesat grade for a total of 6.5 miles of subway
system. A total of four-teen stations, eight underground and six at
grade are included on thesystem. The Initial Route has a planned
expansion to 17.3 miles intilefuture.
On January 15, 1979, a Joint Venture of S & M Constructors,
Inc.,Solon, Ohio, James McHugh Construction Co., Chicago, Illinois,
andKenny Construction Company, Wheeling, Illinois, was awarded
contract1CO031, the Line Tunnels from Amherst Street to South
Campus in north-central Buffalo between Delaware Park and the State
University, (seeFig. 1, Location Plan) This $35,000,000.00 contract
was designed byHatch Associates Consultants, Inc., Buffalo, N.Y.
The Notice to Pro-ceed was issued January 15, 1979 and the
scheduled completion date isAugust 18, 1981.
The project consists of two parallel rock tunnels with a
minimumexcavated diam of 18 ft O in. and a final concrete lining of
16 ftO in. diam. The tunnels total 14,630 linear ft. In addition to
thetunnels, contract C-31 includes four shafts, an underground pump
sta-tion, three cross passage connections, and other minor work
items.(see Fig. 2, C-31 Project Plan and Profile)
The tunnels were constructed primarily within the Bertie
Formation,an approximately 50 foot thick moderately fractured to
massive, dolo-
547
-
,P,/ 1,.
/ CITY LIMITS /
\/
ExTENT OF CONTRACT/
AMHERST ST.~
HUMBOLOT
)
lxu~
\
z
/:\f
)
II //
/
i BEST ST.NORTH S~
o
N
LAKEERIE
MAIN ST.
~
\L._
~.-,.)
L..1
/ftKENSING ON EXPRESSWAY
II
/lI
m
548 1981RETC PROCEEDINGSVOLUME 1
Fig. 1 Location Plan
-
ECONO
MICS
OF
USEDTUNNEL
BORING
MACHINES
549
N.
m.rL
-
550 1981 RETC PROCEEDINGSVOLUME 1
mitic limestone with some thin interbedded shale layers. No
apprecia-ble gas was encountered. The original water table,which
was at orabove the crown of the tunnels,was lowered below the
invert by an ex-tensive deep well dewatering system. The tunnels
start at the north-east end of the project and were both driven
concurrently toward thesouthwest. The tunnels go downgrade (up to
2%) to the mid-point of theproject at the pump station and then
upgrade (up to 0.5%) to the termi-nation. Temporary support
requirements included three percent (460linear ft) of structural
steel rib-supported and ninety-seven percent(14,170 linearft) of
rock bolted tunnel. (see Fig. 3, Typical CrossSections)
S & M as Project Sponsor was delegated complete managerial
respons-ibility for this project by the Joint Venture partners. The
company,which is today called S & M Constructors, Inc.had its
start in theconstruction business in the late 20s and has completed
hundreds ofmiles of tunnels. As a company with a major commitment
to tunnel work,we perceived a need for an efficient and reliable
mechanized rock tun-neling machine. Consequently, in the fall of
1953, we initiated thedesign of a T.B.M. and place our first
machine in operation in October,1965. Since that date the T.B.M.
manufacturing company - Jarva Inc. -has manufactured 29 T.B.M.s
ranging in size from 6 ft O in. diam to32 ft 3 in. diam utilizing
cutter head drive from 200 hp to 2,400 hp.After firmly establishing
Jarva as the second most successful T.B.M.manufacturing company,we
decided to turn the full focus of our atten-tion to contracting and
sold Jarva to Atlas Copco A. B. headquarteredin Stockholm, Sweden
in August, 1979.
With this background, after the award of the C-31 contract, S
& Mdecided to employ two existing T.B.M.s for the boring of
these tun-nels. The first machine we committed was manufactured by
The RobbinsCompany in 1976 and currently owned by James McHugh
Construction Co.The machine, Robbins Model 185-178, was 18 ft 2 in.
diam, had a cutterhead drive of 900 hp and was completely suitable
for this project.The machine was located in Chicago and had been
stored in an as iscondition after completing 11,000 linear feet of
tunnel, loggingapproximately 1,500 hrs of operations at this time.
The second machinewas manufactured by The Robbins Company for White
Pine Copper Companyin 1967. (see Fig. 4, Robbins 185-178, White
Pine Copper Co.) Thismachine, Robbins Model 181-122 , was 18 ft O
in. diam and had 1,200 hpat the cutter head. After boring 8,500
linear feet at the mine, thismachine was purchased by S & M,
rebuilt to 18 ft 6 in. diam and drovean additional 8,000 linear
feet of tunnel in Rochester, New York.This machine suffered major
structural failures and after ten years inthe field was
technologically obsolete.
The rebuild of 181-122 consisted of a major redesign of the
cutterhead, modification of the front support, modification of the
rear sup-ports, redesign of the operators area, redesign of roof
drills, andthe rebuilding and replacement of existing machine
components. (seeFig. 5, Original White Pine TBM and Fig. 6,
Modifications to White
-
TYPE .MACH,., EXCAVATION
!.
,
L
MUFALO LIGHT RAll.Wio ,.s,, ,OJC(
t--
. mo.r!.,,,.. u-.
.. -W- .C.
PRIMARY SUPPORT:a
CONCRETE LINING
DETAILS
Fig. 3 Typical Cross Sections aUJ
-
Fig.4 Robbins 185-178 White Pine Copper Co.
1-
-
ECONO
MICS
OF
USEDTUNNEL
BORING
MACHINES
553
I,
.,. 7,...,,,
,,
I
-
554 1981 R
ET
C P
RO
CE
ED
ING
S V
OL
UM
E 1
-
ECONOMICS OF USED TUNNEL BORING MACHINES 555
Pine TBM)
The cutter headstyle. The cutterthough the bearingair oil mist
seal.
was redesigned from the domed style to the flathead was
redesigned around the existing bearing acavity seal was changed
from a grease seal to an
To provide for a flat cutter mounting surface from the cutter
headto the bore, the eight existing muck buckets were modified and
fournew cutter mounting platforms were made--for a total of twelve
spokes,or mounting platforms. The muck paddles were also changed to
conformwith the new face profile.
To complete the redesign of the front of the machine, the front
sup-ports were reworked. A new stationary lower front support was
made toreplace the existing movable lower front support. The side
supportswere extended above springline and the side support
cylinders were re-placed with new shorter stroke larger bore
cylinders.
The existing 4,160 v 200 hp motors were replaced with new460 v
200hp motors.
The existing thrust cylinders were replaced with larger bore
cylin-ders to give the machine greater thrust potential. The thrust
cylin-der rod diam and rod clevis thread diam were also increased
for agreater safety factor.
The main beam was lengthened by four feet between the gripper
hous-ingand the cutter head support to give the operator better
control ofthe machine for both line and grade.
New wear plates were installed in the gripper housing guide
shoes.New Torque cylinders were also installed in the gripper
housing.
At the back of the machine the single rear support leg was
replacedby two legs. This was done to give better control and
stability whenresetting the machine.
Also, at the rear of the machine, the operators area was
redesignedA new platform was fabricated to accommodate the
operators hydrauliccontrol station, all the electrical controls,
and the hydraulic pump-ing station. The new platform was mounted to
existing mounting padson the rear support housing.
Above the operators platform the main beam was extended with
abolt-on section. This section helps support the operators
platform,provides a mounting for a new 320 gal hydraulic resevoir,
and enclosesthe conveyor.
The conveyor was lengthened to accommodate the lengthened main
beamand new operators platform. The conveyor was refitted with all
newcomponents, including head and foot rollers, return and
troughing
-
I556 1981 RETC PROCEEDINGSVOLUME 1
idlers, oarlocks, and drive motor.
Both the electrical and hydraulic circuits were redesigned and
allnew components were used throughout.
A new roof drill platform was designed and fabricated using some
ofthe existing drill components.
The existing drive gear reducers were rebuilt. The flexible
con-nection, between the drive motor and reducer, was modified to
elimi-nate a problem with reducers.
A new exhaust vent line was fabricated and installed along the
topof the main beam.
As the new and rebuilt parts and assemblies were received in
theshop, the machine was reassembled and tested to assure the
proper op-eration of all the machines components. (see Fig. 7,
Modified WhitePine TBM, Robbins 181-122)
The overhaul of the 185-178 T.B.M. for the C-31 project included
achange in diam from 18 ft 2 in. to 18 ft 7 in. by the extension of
allten muck buckets and the addition of one gauge cutter. All the
elec-trical motors were removed, overhauled and reinstalled on the
machine.All the gear reducers were removed, new clutch assemblies,
bearingsand gears were provided. The main bearing seals were
removed and re-placed. A new conveyor belt including the tension
mechanism and id-lers were installed on the machine. The tail
pulley was overhauledand new seals and bearings were installed. A
new inching motor wasinstalled on the machine. The complete
hydraulic system was rebuiltincluding new fittings, valves and the
rebuilding of pumps as required.The electrical system was
completely reviewed and modifications andrepairs to meters,
switches and consoles was accomplished as necessary.The gripper
ways were shimmed for the new clearance and new wiperswere
installed. The machine was equipped with a new 1500 KVA
trans-former. A new trunnion block and pin was installed for the
grippersystem and all cylinders and ball bushings were reworked and
tested.The roof support cylinders were rebuilt and the side support
cylinderswere rebored and bushed. New pins were installed for all
the cylin-ders. All structural fasteners were replaced.
Both machines, 185-178 and 181-122 were used on the C-31
projectand performed satisfactorily.
-
ECONO
MICS
OF
USEDTUNNEL
BORING
MACHINES
557
-
1981RETC PROCEEDINGSVOLUME 1
Itern
Excavation Diam
Gross Wt
Cutter Head Drive
Cutter Head rpm
Total Cutter HeadThrust
Total Cutter HeadTorque
Cutter Size
No. of Cutters
Total hp
Estimated MaximumPenetration Rate
T.B.M. COMPARISON - Design
McHugh White PineOverhauled Modified185-178 181-122
18 ft 7 in. 18 ft 6 in.
235 tons 350 tons
900 hp 1,200 hp
5.1 7.5
1,911,000 lbs 2,155,000 lbs
924,286 1,720,000ft-1bs ft-1bs
15% in. 15% in.
43 43
1,025 hp 1,375 hp
10 fph 12 fph
New QuotationTypical
18 ft 6 in.
280 tons
1,000 hp
7.8
2,000,000 lbs
1,000,000 ft-lbs
15% in.
42
1,100 hp
10 fph
-
ECONOMICS OF USED TUNNEL BORING MACHINES 559
T.B.M. COMPARISON - Cost & Production(Based on Estimates
& Records)
Itern
EstimatedDelivery Tiem
ActualDelivery Time
First Cost
ModificationsIncluding Opera-ting Expense
Total Job Cost
Estimated Salvage
Estimated Jobcost
Linear FeetBored
Operating hrs
PenetrationLinear fph
Cutter Cost
Total Cost
Cost per LinearFoot Bored
McHughOverhauled185-178
3 mons
4 mons
$1,500,000
$ 615,000
$2,115,000
$ 750,000
$1,365,000
7,003
1,750
4.0
$ 160,000
$1,525,000
$217.86
White PineModified181-122
6 mons
9 mons
$ 700,000
$1,090,000
$1,790,000
$ 500,000
$1,290,000
7,000
1,750
4.0
$ 160,000
$1,450,000
$207.14
New QuotationTypical
12 mons
$2,900,000
$ 300,000
$3,200,000
$1,000,000
$2,200,000
4.5
$ 200,000
$2,400,000
$342.86
-
560 1981RETC PROCEEDINGSVOLUME 1
The tabulations presented are based upon actual records and the
es-timates for new equipment. Due to the vagaries of field cost
report-ing and the limited data from this project, a recapitulation
temperedby experience and logic leads me to the following
conclusions:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
A properly overhauled, relatively new machine may or may not
bethe most economical for a given project.
A minor modification of a relatively new machine is more
economi-cal than a new machine.
A major modification of an existing machine is more
economicalthan a new machine.
A new machine is the most expensive for a given project.
A major modification of an existing machine including an
updateincorporating the latest technological advances can be
accom-plished with a reasonable cost outlay and can be completed in
lesstime than the current delivery for a new tunnel boring
machine.If this work is properly executed, the resultant T.B.M.
will beequal to or better than a new machine.
The use of rebuilt or overhauled T.B.M.s can be a major
advantagein the construction schedule.
Due to the lower initial cost, a used T.B.M. will generally
proveto be more economical than a new machine.
A used T.B.M. with minor modifications and overhaul will
requireless time to erect and debug for a given project.
As the use of T.B.M.s increases, a major market will develop
forused machines.
The operating characteristics of overhauled and updated,
rebuiltand new T.B.M.s are not distinguishable.
The operating costs of overhauled, rebuilt and new T.B.M.s
arenot distinguishable.
The cutter costs of new, overhauled or rebuilt T.B.M.s are
notdistinguishable. The economic life of T.B.M.s is
certainlygreater than 10,000 hrs as has been proven in the
field.
The ownership of a used T.B.M. can be a major asset for
under-ground construction contractors, limited only by the
versatilityof its diam and the inevitable structural
deterioration.
-
ECONOMICS OF USED TUNNEL BORING MACHINES 561
REFERENCES
Jarva, Inc.- 1980- Personal communication.
James McHugh Construction Co. - 1980 - Personal
Communication
The Robbins Co. - 1980 - Personal Communication
S & M Constructors, Inc.- 1980- Personal Communication
White Pine Copper Co. - 1980 - Personal Communication