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-

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Fig. 1 Location Plan

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549

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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

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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.

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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:

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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