In 1978 the Robbins Company of the USA produced TBM 213-190 as a state-of-the-art main beam machine set up to work on the deep tunnel system in Chicago for contractor Traylor Bros of Evansville, Indiana.
The machine’s drive system and disc cutter array was the highest capacity ever developed at the time. The resulting boring rates during the 12,950m-long project in dolomitic limestones met performance expectations and the project was considered a success apart from three main bearing failures. These were attributed to some unusual wye cut sections with their related eccentric loading on the bearing.
On completion of the project, the machine was sent to the contractor’s yard for storage. This involved dry storage of the critical components such as the main bearing, bull gear, drives, electrical components and operator console, along with a clean-up, and a blast and paint coating of the remaining structures. The preparation was in anticipation of follow-on work on TARP extensions or other suitable jobs.
In the event it was 1993 before a second life opportunity came for the machine which had languished in its yard for more than 12 years. This chance arrived when Traylor Bros in joint venture with Frontier-Kemper Constructors, also based in Evansville, won a contract for a difficult job on the Red Line Metro project in Los Angeles, California.
Two machines was needed for the job, in ground conditions that were distinctively different geology from Chicago. Mixed materials were expected, requiring constant ring steel support and face control, along with reduced ground pressure disturbance that would result from dead-weight loading or from gripping forces.
It was planned to use beam style machines with special configuration changes. TBM 213-190 was a suitable diameter, as was another beam machine manufactured in 1976, which was also in storage after completing its second project in 1987.
Construction & Tunneling Services (CTS), which had helped prepare a pre-bid review of machine options for the joint venture, began to work in earnest on a significant transformation of the machines for work in Los Angeles.
Extensive modifications were needed to the main drive train, with new cutterheads, additional structural pieces to lower ground pressures of the machines, amd an auxiliary thrust system to work in conjunction with a production oriented ring beam and mesh ground support system. A drill arrangement provided full face coverage for ground consolidation by grouting, with a hoist and placement system to handle the invert block scheme considered essential to maintaining a quality mainline rail alignment throughout the drive. With these changes, the machines effectively became twins.
The changes to the main drives were the most significant factor in updating the two machines from vintage equipment to 1990 contenders. The main bearing dimensional envelopes were reworked, taking advantage of 1990 main-bearing technology which could produce significantly higher capacity bearings using asymmetric rolling elements.
Both systems’ capacities were raised to match thrust level requirements of the disc cutters, which had increased from 18mt per disc in the 1970s to 25mt per disc. This was augmented by an increase in machine torque that produced 2.5 times its prior level. This was achieved with the addition of two drive units and the conversion of all units from single speed electric to full variable speed hydraulic. The gearing components, pinions and gear, and the structural connections were upgraded to increase torque and thrust capability.
With the hearts and muscles of the machines strengthened, it was possible to employ close-breasted cutterheads with backloading high thrust cutters in the most effective way – controlling a mixed face by a combination of speed control and thrusting with material in contact with the flat face.
The machines had indeed reached a new technical level that prepared them adequately for a successful project, which was completed in 1997. As was common practice in the 1990s, the pair were named prior to their launch, appropriately for the Los Angeles and Hollywood environment as Thelma and Louise. Like the characters in the movie, the machines traversed difficult conditions from beginning to end. Unlike them, the machines were put into storage at the end, rather than killed off.
Thelma did not rest very long before being cast in an entirely new configuration. This came in the autumn of 1999 when the contracting joint venture of Traylor Bros and Jay Dee Contractors, known as Traylor-Jay Dee, received a contract for a 7.2m diameter x 1,985m long drive in the city of Detroit.
This project was considerably different from that in Los Angeles in that it was to extend a sewer outfall system under a river through discharge diffusers. Concerns related to ingress of water with high levels of hydrogen sulphide (H2S) anticipated large volumes of water charge through probing and grouting sections, installation of final lining, and ultimate removal of the machine from a dead-end tunnel after a drive in a corrosive atmosphere.
The logical machine configuration was for a single shield, equipped to set segments inside a wire brush-sealed tail section for limited water ingress, a patterned drill-and-grout arrangement, and with thrust and cutterhead capability to cut moderate strength rock formations.
A shield machine configuration is significantly different from a beam style in that it thrusts from lining elements rather than from ground gripping devices. Torque control devices provide restraint using the ground or the lining rather than the gripped anchor point of a beam, and circumferential thrust cylinders act as steering elements.
Early in the planning stages the joint venture and CTS designers realised the potential of using the heart of Thelma and building the additional structures and systems. The modifications to the drive system for the Los Angeles job paid dividends as the new machine configuration established by the designers was able to use the existing core system in its entirety.
Other parts that were resurrected for the project included the inner cutterhead structure, the trailing gear with modifications for segments and back-fill grout systems, ventilation fans, and electrical and hydraulic components.
New structures were designed and manufactured for the shield, propulsion system, erector and segment handling system, and the drilling arrangement.
During the final shop assembly and test procedure, all parties agreed that the changes were so significant they qualified as a complete ‘sex change’ and the machine was renamed Max.
Max has just begun his journey in Detroit. In the meantime the original components that can return him to a high performance main beam configuration are sitting in storage waiting for the call to new and innovative uses. Given the transformations since the birth of this Robbins TBM 213-190, it is conceivable that many more lives will be possible for the machine.
How ‘Fat Allis’ lost weight
Starting in the 1970s the Chicago TARP project is a huge endeavour, which has required numerous machines. Today the system of underground reservoirs is still expanding with additional tunnels in the outlying districts. A 6.7m TBM is running on the Thornton reservoir leg for the contractor joint venture team of JayDee-Traylor, and a 5m diameter x 12.5km long tunnel section for the Little Calumet Leg is scheduled to go out to bid in early November.
One of the early machines on the project was TBM 321-199, a 9.9m diameter Robbins beam machine produced for the joint venture contracting team of J F Shea and Peter Kiewit & Sons in 1979.
The machine completed its initial 4,200m drive in Chicago limestone in the late 1970s, with an average production rate of 332m/month, and was then put into storage. By the time additional work in Chicago came up in the 1990s, other TBMs had been manufactured during the late 1980s which had more power, larger installed torque, and higher thrust using larger capacity cutter assemblies. The resultant production improvements were advantageous, particularly over longer drives.
To match this capacity the TBM required similar revisions and upgrades to the drive system as the TBM 213-190. Changes to the power and main bearing gave higher cutterhead thrust, allowing larger thrust capacity cutters with their related production improvements and effectively bringing the 20-year-old machine up to current standards. The machine was reworked in an idled factory of heavy equipment manufacturer Allis-Chalmers located in West Allis, Wisconsin. The assembly of large structures that made up the tunnel machine earned the nickname Fat Allis.
The second 3,975m long drive in Chicago was completed successfully in 1992 with the machine maintaining an average production rate of nearly twice its previous record, beating all machines in its size class. So after some 8,175m of tunnel over 15 years, Fat Allis had competed against state-of-the-art technology and proved omparable. The machine was then prepared for an undefined storage period, with no knowing what its next transformation was to be.
In the autumn of 1995 a project in Chicago was bid for, which was ideal for a machine with high power and thrust characteristics. However, the diameter requirement was for 7.4m, 50% smaller than Fat Allis’s 9.9m diameter. But if the drive system of a larger machine could be ued, who knew what new production records were possible?
At first glance, too much of Fat Allis’ structure, including the gripping and torque reaction system would have to be eliminated to fit the smaller diameter. To reinvent the interfering structure and systems would be prohibitively expensive. Fortunately, the CTS design group accepted the challenge to develop the system that enabled the core machine to be used and to create structure and systems that provided gripper, torque reaction and propulsion in the smaller space that was available.
This significant structural modification involved removing the beam structure with its integral gripper carrier, rear section and propel system in favour of an open gripper, with torque reaction and propelling force provided by latticed ‘vee’-cylinders that were connected between the gripping shoes and the forward structure.
This setup was used on CTS-patented continuous boring rock machines, developed to open up the centre space of machines. It is achieved by tipping the attitude of the propel cylinder so that it could react both thrust and torque. New propel cylinders and gripping shoes able to use the existing grip cylinders were used to complete the thrust system.
The original cutterhead drive assembly was fitted into a 7.4m diameter shielding structure which had been specially designed to accommodate the new thrust arrangement. The large main beam was sent to storage, replaced with a structure that provided support for the main conveyor and the new hydraulic system and bridged the distance between the front shield and the trailing gear. In this way, what looked to be an unlikely opportunity for Fat Allis became a reality and the machine went on to raise the performance standard for Chicago work.
A drive of 10.4km followed at 8.35m diameter, with average progress of 52.3m/day and a best month of 1,155m. By 2000 Allis had completed 17,450m of tunnel work in the Vee cylinder configuration.
A visit to the contractor’s yard today finds Allis waiting patiently, alongside its two sets of running gear, to be called on again and hoping that the design teams that brought her back to life in a new form will continue to rethink the configurations that keep her active.
For the original producers it is a mixed blessing to see their TBMs continue to perform successfully on a succession of projects as it means loss of new sales opportunity. But the efforts of contractors in operation and storage, and designers and re-manufacturers in modifying and re-using machine cores for second, third, and fourth lives must be applauded.
Related Files
Overlaid longtitudinal sections
