James H. Slagle
,
J. M. Hill
,
W. B. Davison
,
Wood Hart
and
José Teran U.
The University of Arizona
Hart Construction Management Services, Inc.
M3 Engineering & Technology Corporation
Steward Observatory, Tucson AZ 85721-0065, USA
P.O. Box 1416, Safford, AZ 85548-1416, USA
2440 W. Ruthrauff, Suite 170 Tucson, AZ 85705-1950, USA
TABLE OF CONTENTS
Planning, estimating, and building a telescope and its enclosure within a budget is a challenge to any project staff. The Large Binocular Telescope (LBT) project office goal has been to break every phase of the project into small packages and competitively bid the packages. In this way the project office can minimize costs and keep the project budget from escalating out of control. This paper will discuss both the unique and common problems associated with the building of telescopes into the next millennium. The discussion is centered on the planning and execution phases of construction for the LBT, located on Mt. Graham in Arizona. The paper will discuss the effects of delays on the actual start of the telescope due to environmental issues and the impact the delays had on design and budget. The paper will provide the solutions that have been incorporated by the LBT project office to maximize the quality of construction while holding costs to a minimum. The use of a team approach by the contractors, engineers, and the project office has been successful in maintaining quality construction at a reasonable cost.
KEYWORDS: telescope construction, enclosure construction
The Large Binocular Telescope (LBT) Project is constructing a binocular telescope with two 8.4 meter primary mirrors on a common mounting. Those mirrors provide a collecting area equivalent to an 11.8 meter circular aperture plus a diffraction baseline of 22.8 meters. The F/1.14 focal ratio of the primary mirrors allows the construction of a relatively compact telescope enclosure. This paper deals with the design of the telescope enclosure and the on-going construction of the enclosure on the mountain. The enclosure shown in Fig. 1 is a co-rotating box structure which would be considered conventional if not for the two side-by-side entrance slits. Additional details of the telescope are described by Hill & Salinari (1998).
The original planning and site selection for the LBT began in the mid-1980s. The general site selected was on Emerald Peak, the third highest peak in the Pinaleño Mountains of southeastern Arizona. The location is a three hour drive from The University of Arizona in Tucson. The construction of the Vatican Observatory 1.8 Lennon Telescope (VATT) and Heinrich Hertz Sub-Millimeter Telescope (SMT) were successfully completed in 1993, but the start of construction for the LBT was delayed due to legal concerns until June of 1996. Even though the time delay was a severe blow to the project and its partners, the project office used this time to insure that the telescope design would continue to incorporate cutting edge technology. The delays also meant that the project office would have to deal with increasing costs and inflation.
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| Figure 1. This figure shows an artist's rendition of the LBT enclosure. Artwork by Northwest Graphics S & A (Bainbridge) |
Faced with an uncertain start date, the leadership of the LBT directed its efforts to insure that the telescope, mirror, and enclosure portions of the project would be ready to begin once a legal remedy was established. Design reviews were periodically held to determine refinements, changes, and possible impacts to a start date. The management team for the operational planning was comprised of both the LBT project offices of The University of Arizona (Tucson, Arizona) and Arcetri Observatory (Florence, Italy). Led by the Project Director, John Hill, the Deputy Director, Piero Salinari, and the engineering and architecture firms of M3 Engineering & Technology Corporation (Tucson, Arizona), European Industrial Engineering S.r.l. (Mestre, Italy), and ADS Italia S.r.l. (Lecco, Italy), this group would insure that the designs for the telescope, support equipment, and the enclosure were continually reviewed and modified. While driven to insure the highest degree of instrument sensitivity, the LBT design team was also mandated to follow the budget developed in 1989. From the beginning, the design goal of the LBT enclosure was to build an economic enclosure that would enhance the operation of the short-focal length mirrors. The use of structural steel elements standard in the industry coupled with minimal welding would also save material as well as construction costs.
The enclosure was designed to fit the site and the telescope. Erection of the enclosure requires that careful attention must be paid to critical tolerances. The co-rotating type enclosure requires less volume which is important since the site is very restrictive and difficult to access with large equipment. Since there is less overall volume, the floor area is less expensive; however, the steel floor system acts as a stiffener, reducing the amount of steel required overall. The interior design allows for easy movement of large pieces of equipment (10 meter diameter). Roller chain drives for the shutter and ventilation doors allow for a higher tolerance for structural deflection during the operation of the doors with the added benefit of requiring less machined steel. The shutter doors were also designed to act as stiffeners for the rotating portion of the building during survival conditions. This, once again, eliminates the need for additional steel while providing an internal structural system. The design takes advantage of conventional framing and emphasizes the use of bolted connections instead of welded connections which is important to the sensitive forest environment. The thermal and seeing aspects of the enclosure design have been discussed by Salinari & Hill (1994).
In 1989, the project leaders provided for a budget of 60 million dollars to build the LBT. One quarter of the budget was for the enclosure. Between 1989 and 1996, the project managers added a conservative inflationary figure to the budget to supply realism to a project that they could only plan but not execute. By using the 1989 figures as a baseline, the project manager could maintain the cost controls needed to keep the project from moving away from its original concepts. In all phases of design of both the telescope and the enclosure, astronomers, engineers and scientists were continually looking for methods to keep the telescope and its enclosure to a realistic cost that paralleled the estimate in 1989.
The 1989 budget reflected the goals and objectives of the LBT. All management members agreed that everything should be done to keep the project on the early financial goals which included a yearly inflationary cost increase of approximately 3% a year. It would not be until 1996 that a re-evaluation of the budget using a construction cost index (Ref. 3) would show that the 3% figure would be close to the actual construction cost inflation over the same time frame. One area that could not be calculated or estimated was the increase in cost of constructing a 162 foot (55 meter) high building on a 10,500 foot (3,200 meters) mountain located 100 miles (160 kilometers) away from the nearest major material source.
The project office was committed to removing unnecessary expenditures and to insure every dollar was accounted for. Rather than turn the project over to a large general contractor, the project office decided to look at the local resources close to the construction site. The project office selected a local contractor, Wood Hart of Hart Construction Management Services to serve as the general contractor for the LBT project. Wood has over 35 years of experience with major construction companies and at increasing levels of heavy construction management. Wood had also served as a technical advisor on the construction of the VATT and SMT. As the general contractor, Wood agreed to work side-by-side with a member of the project office. This was an unusual relationship in that HCMS and the project office would share risk and responsibility for the construction of the enclosure. The project office would share in the risk involved in providing quality contractors and a competitive price to work in very difficult and unusual conditions. The intent of the project office was to have competitive bidding on every aspect of the job yet keep to a very tight operational schedule. Because the project office selected a local general contractor, the project could avoid loyalties to sub-contractors normally found in larger general contractor firms. The problem would be to identify sub-contractors who would be willing to work as part of a team and under difficult working conditions.
The location of the site presented major obstacles to every potential sub-contractor for LBT. Because of the location and altitude of the site, the construction season historically is between April and November of each year. Winter weather with snow levels between 5 and 15 feet, temperatures with wind chill factors below minus 20 degrees Fahrenheit, coupled with roads difficult for large equipment, eliminated normal construction procedures. The LBT site is located within an endangered species refugium area which is closely monitored by the U.S. Forest Service. The site is only 1.2 acres. Construction workers would have to be transported over 35 miles of curved paved and unpaved roads which narrow to one lane in width. The average length of time for a one way trip to the site is between 75 and 90 minutes. While on the site, the workers would be responsible for not only the quality of their work and their equipment, but for cleanliness of the site. Any disturbance of the refugium area by litter, food, etc., could not be tolerated. Because the building structure occupies 65% of the site, there is little room left for the contractors to store materials and to bring major pieces of machinery for installation purposes. The problem would be compounded by the need to have multiple contractors doing multiple activities on the site at any one given time.
During the beginning of 1996, the project was still on hold and embroiled in legal delays. The project office used this time to begin planning its strategy and identify possible sub-contractors. With the help of the general contractor and with guidance from the architects, a list of potential sub-contractors was assembled. The object was to competitively bid every sub-contractor phase. This would involve a formal bid phase and would provide the project office with a sound cost comparison. Each contractor would then be visited and provided with a comprehensive explanation of the work requirements and the associated problems. On-site visits by potential contractors were essential. Because the LBT project was unsure when it would be allowed to proceed, it was very difficult to get a contractor to commit to the project. The project office would only be able commit to carefully controlled ``time and material'' contracts.
On June 28, 1996, LBT construction would begin without legal encumberments. Earlier meetings with sub-contractors allowed the project office and the general contractor to issue contracts for work to proceed immediately on the site. For the next four months, construction crews would rough in the access road, remove the last of the trees per Forest Service specifications and shape the site by the removal of rock. Immediately, there were problems. An early estimate of rock to be hauled off the mountain, based on aerial photographs, was placed at 2,400 cubic yards. The actual amount of rock that was removed from the LBT site was over 8,000 cubic yards (see Fig. 2). This did not include rock that was screened for use in later site fill requirements. The project office and general contractor were able to reduce the total cost of this removal by providing large quantities of rock to the Arizona Department of Transportation and the U.S. Forest Service. The rock was used for fill in road projects and was stored in areas for further use in agency planned projects. The ability of project management to work locally with area agencies saved the project significant money in unplanned hauling costs.
Because of the sensitivity of the site being located within the refugium of an endangered species, the project office/general contractor worked closely with the Forest Service and University of Arizona biologists to plan the type and method for blasting of the rock. The project office, working closely with the sub-contractor in charge of the site clearing, selected a blasting specialist. Blasting plans were coordinated through the Forest Service to insure that both sound and the amount of airborne particulate were minimized. University of Arizona biologists were given time to set up sensitive monitoring equipment around the site. The general contractor incorporated all of his excavation requirements into the blasting plan so that the number of blasts would be minimized. The blasting specialist, in coordination with the Forest Service and the sub-contractor, provided his recommendations as to the type and method of explosive. This entire effort took less than two weeks and resulted in not only a success from the construction point of view, but satisfied the biologists and Forest Service that there had been a minimum impact within the refugium area. This effort also minimized the cost for the rock excavation since it minimized the number of individual blasting operations on the site.
During the bid process both large and small contractors were invited to bid. One small concrete contractor who was willing to provide his services on a time and material basis was David Weaver of Peterson-Weaver Concrete in Mesa, Arizona. David had no telescope experience but was enthusiastic about the challenge. Peterson-Weaver quickly became part of the LBT construction team. They worked with the project office and general contractor to provide the best possible costs on equipment and materials. During this first construction year, they would pour the foundation for the telescope pier. Meticulous in every detail, David insured his tolerances on form work using laser surveying equipment at every level of work. David would later tie his concrete to the center core of rock within the foundation excavation. The result was an 800 cubic yard pier foundation tied into the mountain and shown in Fig. 2.
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| Figure 2: These photos show the excavation on the Emerald Peak site in 1996 (left), and the concrete foundation for the 46 foot (14 meters) diameter pier (right). | |
Because of the short construction season and the necessary requirement to have multiple functions occurring on the site at one time, the winter season is used by the project office and general contractor to schedule the next season. The 1997 season was important to the LBT team since it would be the first full construction season with the goal of completing the telescope's lower enclosure. This meant that contractors for concrete, steel, electrical, plumbing, and cladding would have to be identified. During the 1997 construction season, over 3000 cubic yards of concrete and 150 tons of steel would be erected on the mountain. Workers would face an unusually long ``monsoon season'' that would result in their work day starting at 4:30 in the morning to insure that a standard day could be completed before the afternoon rains rolled in.
Contracts during 1997 were awarded in a variety of different ways. Each contract would be tailored to the type of work to be done. The concrete contract issued to Peterson-Weaver was a ``not-to-exceed'' contract due to the tolerances required for two large concrete structures and other major concrete pour requirements. The central pier would require a height of 62 feet (19 meters) and an outer ring wall to support the rotating building would rise to 38 feet (11.5 meters). Large metal forms were radiused to within a quarter of an inch tolerance and the two walls shown in Figs. 3 and 4 were completed within 5 months.
A guaranteed maximum price contract was written for the structural steel. Schuff Steel, Phoenix Arizona, has been committed to providing the best in shop and on-site support. From the very beginning of negotiations, their Chairman of the Board, Dave Schuff, stated that he wanted his company to be a part of the LBT project. His energy and commitment has been transmitted to every level of the organization. It should be noted that in all cases, the drawings by M3 Engineering & Technology supplied with the cost proposals were considered by the contractors as the ``most complete'' drawings they had received for a technically demanding job like the LBT. The quality of the drawings was also responsible for the fact that during the 1997 construction season, there were only two change orders that required additional funding. Finally, time and material contracts were written for the dirt work, electrical, drilling, and plumbing work that supported the major contracts.
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| Figure 3 This figure shows the concrete forms for the telescope pier and the encolsure ring wall in June 1997. Over 3200 cubic yards of concrete were used in the pier and ring wall. |
The method of using local contractors and bidding all aspects of the job is not new to the construction of telescopes. In the case of LBT, the unusual legal delays coupled with a limited budget provided the constraints that the project office would have to work in. What has evolved is a strong partnership between the project office, the general contractor, the architectural and engineering firm, and the contractors. The partnership has led to a team environment where problems are identified before they cost time and money. There are many unique characteristics to this partnership.
The general contractor has provided the leadership and knowledge demanded by a job of this magnitude. In any construction project, the owner wants a quality product with minimum delays and budgetary problems. Wood Hart has proven to be an excellent leader and manager who has the ability to visualize what has to be done weeks prior to the work. While on a separate schedule, he works daily with the project office to insure that the project goals and budget requirements are being met. Safety was an essential part of this work. The general contractor initiated a comprehensive safety program from the first day of construction.
M3 Engineering & Technology has provided the daily interaction between project office, general contractor and sub-contractors. Every aspect of the shop drawings are reviewed and returned in 3 days or less. On-site inspections for payment certification provide forums to work out problems and answer questions to the sub-contractors. In many cases, changes in procedures initiated on site have resulted in major cost savings due to the team approach of building LBT.
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| Figure 4: This figure shows the concrete ring wall which will support the rotating enclosure in July 1997. The inner cyclinder is the concrete telescope pier. The use of EFCO metal forms allowed tolerances to be held to a quarter inch. |
Each contractor has been selected not only on cost and quality but on the attitude displayed at the negotiations. Because LBT construction is unlike most general construction projects and the location presents unusual obstacles, contractors must display a willingness to work in the team approach. Peterson-Weaver, Schuff Steel, Sure Steel, Western Technology, A.J. Gilbert Construction, Joe's Plumbing, and Gilbert Electric Company have all shown this desire to be part of a successful construction program. Arizona is an open state concerning union versus non- union employees. While LBT has employed both union and non-union companies, there has never been a problem with the cross-over of lines when working on the site. Each company realizes that in order to meet the construction schedules, multiple operations must be done on site. Even the sub-contractors and suppliers to the contractors have displayed the attitude of a team approach.
The 1998 construction season will begin with Sure Steel (Salt Lake City, Utah) hanging the roofing and siding for the fixed portion of the enclosure. As soon as the weather is warm enough, we will be casting the steel embedded beam sectors on top of the ring wall. The embedded beam supports the circular rail on which the bogies of the rotating building will roll. The embedded beam sectors shown in Fig. 7 and circular rail sectors have been machined by Fravit S.r.l. (Lecco, Italy). The bogies are being fabricated by Costamasnaga S.p.A. (Lecco, Italy) and SIAG S.r.l. (Milan, Italy). After the bogies have been positioned on the circular rail, Schuff Steel will be erecting the 1200 tons of steel frame for the rotating portion of the enclosure.
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| Figure 5: This figure shows the steel framework of the lower, fixed enclosure in September 1997. |
The LBT project is about to enter its third year of construction. New contracts have been let with the goal of completing the rotating structure and the enclosure concrete and cladding. Peterson-Weaver Concrete, Schuff Steel, and Sure Steel will return to the mountain. Competitive bidding coupled with very complete drawings has resulted in contracts that are acceptable on both quality and budget goals. By competing and negotiating every phase of construction, the project office has been insured that it is getting the most for its dollar. This method does require a great deal of time and effort and the decision cannot be based on low bid. The success, so far, in the LBT construction has been on the personal conviction that each contractor has made to the project. In each contract, the winning contractor has proven that they understand they are not providing a normal product. They realized that their efforts will result in cutting edge science. The enclosure that they are building will house the world's most technologically advanced telescope. They continue to build with pride knowing they are part of the LBT team.
Up to date images of the LBT construction can be found on the world wide web at URL
http://medusa.as.arizona.edu/lbt.html
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| Figure 6: This figure shows the steel framework of the high bay portion of the fixed enclosure in September 1997. Note the 34 foot high door opening on the right side to allow for the installation of the 8.4 meter mirrors. |
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| Figure 7: This figure shows one of the nine Embedded Beam sectors which support the rotating enclosure being machined at FRAVIT S.r.l.. FRAVIT is a manufacturer of large mechanical components with the capability of NC machining at very small tolerances. |
http://medusa.as.arizona.edu/lbtwww/tech/encl98.htm