Large Binocular Telescope - Mount Graham International Observatory
Precision Heavy Haul Inc. Presents: A Sight Beyond Belief
As a new millennium dawns, a giant new telescope will begin to observe the heavens in a way never before thought possible. Located near the summit of Mount Graham , a plateau high above the desert of southeastern Arizona , the Large Binocular Telescope (LBT) represents the opportunity to pursue the age-old human quest to understand the origin of the universe and all it contains.
The problem: How to get a 10 million dollar, one of a kind, largest in the world, telescope mirror up to the top of a 10,500 foot mountain peak, in one piece, on a road that was built by the Works Progress Administration (WPA) in the 1930’s under the Hoover administration. That was the challenge faced by Precision Heavy Haul, Inc (PHH) of Phoenix , AZ when they contracted to transport two major components of the LBT from the Steward Observatory Mirror Lab at the University of Arizona in Tucson , AZ. , to the Mount Graham International Observatory (MGIO) enclosure at the top of Mount Graham , near Safford , AZ. Upon final construction of the first of two primary mirrors, with winter weather conditions approaching, a journey up the mountain needed to be completedin a timely manor to ensure the entire LBT work scope stayed on schedule. All aspects of a haul of this magnitude, from permitting to overnight pullouts, must be coordinated and executed to perfection. High winds and snow are not uncommon during the fall months on Mt. Graham , making hazardous traveling conditions a concern. A close eye on the weather would dictate the window of opportunity for each three-day haul.
Three loads were scheduled to be delivered to the mountain top. The first component transported was a dummy mirror; used for load tests. The second load was a mirror cell, which will support the mirror on the telescope. The final load was a parabolic mirror, the first of two primary mirrors for the binocular telescope. When the LBT is fully operational, it will be the world’s most powerful and advanced research tool in optical and infrared astronomy, capable of imaging planets beyond our solar system. This telescope will be nearly ten times more powerful than the Hubble Space Telescope.
The mirror, 8.4 meters (27½ feet) in diameter, three feet thick and weighing 18 tons, is not self-supporting. For transportation purposes it was supported in a specially constructed box having 280 pneumatic actuators thatrestrained and cushioned it in every direction. The mirror and box together were about 30’1″ feet square, 9 ½ feet thick and weighed about 55 tons. The cell, which will support the mirror on the telescope is approximately 29 ½ feet in diameter, 9 ½ feet thick and weighs about 50 tons.
The mirror is very expensive, required years to produce, and is quite fragile. Therefore, the University designed and built a dummy mirror out of steel that closely modeled the real mirror in size, weight, location of the center of gravity and stiffness. Every operation that was to be performed on the mirror had to be first performed on the dummy mirror, thus allowing a check on the adequacy of the mirror box and the transportation and handling systems.
The route from Tucson included 122 miles of interstate and state highway to the base camp near Safford. PHH loaded the mirror transport box and its precious cargo at U of A’s Mirror Lab, located in the campus football stadium. The mirror-carrying convoy pulled out of the lab hours before dawn, accompanied by 2 civilian and 25 police escort vehicles consisting of University K-9 units and Paramedics, Sheriffs Department, and Highway Patrol. The car and motorcycle escorts formed a rolling blockade as the mirror traveled down Interstate 10 and State Highway 191. These officers provided both traffic control and mirror safety as the convoy averaged 45 mph to the MGIO base camp, located at the base of the Pinaleno Mountains . A large number of law enforcement was utilized due the history of threats made by environmentalist groups. Some stating “A mirror will never make it to the top”.
The team arrived at base camp safely and faced an additional 29 miles upthe tortuous Swift Trail (HWY 366) to the mountain top. Traffic control was strictly enforced by police units and message boards along the route, allowing vehicles only to pass at predetermined pullout points. This last 29 miles averaged more than 5% grade over the entire length, with some areas as much as 12%. There were numerous switchbacks, with extremely short radii and lateral slopes up to 22%. In fact, 523 curves and switch backs were noted.
The Tucson to base camp portion of the haul utilized a nine-axle trailer. The load beams were high enough for the loads to clear roadside obstacles, and low enough for overhead clearance. All loads were supported horizontally on the beams. The Mount Graham portion of the road was much too narrow to accommodate the components loaded in this manner. It was noted that most of the road was a side hill cut with the bank on the right and the canyon on the left. Further calculations determined that if the loads were tilted up on the right hand side through an angle of 60-70 degrees, they best fit the mountain profile. At 60 degrees, the loaded height was 33’0″, the width 21′ 3″ and the center of gravity 17’10” above the ground.
The position of the load versus the mountain was thus determined. The challenge remained one of selecting the proper equipment that would sustain that position, maneuverability, leveling as required, and provide a comfortable factor of safety against overturning. It was obvious from the load and road requirements that a European platform trailer would best fulfill the needs. Selected for this task was a six-line Goldhofer for its capacity, stability and maneuverability. The twelve axles are normally grouped into three sets of four in a triangular distribution that allows the trailer to negotiate warped surfaces without significant effect on the individual axle loads. Alternatively, they may be grouped into four groups of three in a rectangular load distribution. This configuration has approximately 50% greater lateral stability against overturning than the triangular distribution, but introduces the problem of axle groups on opposite corners tending to take the entire load on warped surfaces. This tendency is modified by tire deflections and twisting of the trailer frame and, more importantly, by manually adjusting the hydraulic pressures in the four groups.
The high center of gravity and large cross section made the load very susceptible to overturning from side slopes or wind loading or a combination thereof. We therefore accepted the four-point loading configuration along with its operational problems. It was decided additional stability could be gained by adding counter weight to the loaded configuration, placing the combined center of gravity as low as possible. The amount of counter weight was determined by subtracting the weights of the load, the support frame and the trailer from the rated capacity of the six axles on one side. Thus, 70,000 pounds of 8 X 20 foot steel plate was placed on the trailer deck, lowering the combined center of gravity by 2 feet 10 inches. This final configuration had a lateral overturning angle of 16.6 degrees, an increase of 107% over a three-point system without counter weight, and 30% over the four-point system without counter weight. It also has a safety factor of 2.6 against overturning from a 75 MPH wind.
The support frame, designed, engineered, fabricated, and assembled to the trailer by PHH had to accommodate both the mirror box and the cell. Theloads varied approximately 6 inches in length and hard points to which supports could attach varied by 10 inches in the lateral direction. The longitudinal difference was accommodated by designing bolted trunnions that were sufficiently strong enough to support the load over a substantial length. The actual attachment to the trailer needed to be easily connected during loading and unloading, yet meeting the special requirements of each load.
One problem was that the four supports on the loads were fixed with respect to one another as the loads were quite rigid. The support points on the trailer, however, could vary substantially from one another as the loads on the four-axle groups varied with the road conditions and corresponding hydraulic adjustments. The trailer and support frame were quite limber yet the loads were rigid. Therefore, if the corresponding points of the trailer and the loads were joined rigidly together, the variations in the trailer geometry would impose unwanted forces on the loads. This was solved by designing the frame and the trunnions from the forces resulting from hanging the loads from the top supports and resting either of the lower trunnions against the frame. Thus, as the trailer and frame distorted from the varied axle group pressures resulting from the tortuous twists and turns of the roadway, either of the lower supports could lift off as required to accommodate the differences in distortion.
The four-point suspension system was less sensitive than expected, and the trailer operator was able to maintain pressure and level conditions withinacceptable parameters with rare stops for adjustments. These adjustments happened most often on the unpaved portion of the road where significant wash-boarding of the surface existed. In these areas, three undulations of wash boarding corresponded roughly to the axle spacing and the amplitudes of oscillation about the longitudinal axis tended to build up quickly. When forward motion was stopped, the system returned to normal in 10 to 15 seconds. Experimentation showed that slightly increased speeds improved the performance in these areas.
Power for the moves was provided by a 2004 T-800 Kenworth tractor with special low speed 8.40 ratio rear ends towing and a Caterpillar 980 front-end loader pushing. This equipment worked well together at speeds varying from 0 to 4 miles per hour.
Communication was of the utmost importance in making the hauls as safe and productive as possible. Fitted with voic e activated radio and head sets, the drivers of the tractor and loader were able to compare RPM and speed to pull the grades successfully. Identical sets worn by the trailer operator and spotter allowed all members of the haul team to be well-advised on what every inch of the route presented. One police escort was on this private channel so all parties involved were in constant radio communication.
Precision Heavy Haul experienced one delay while moving the components. During the second day of the mirror transport, lead police escorts, radioed; they had encountered a group of men with firearms and propane tanks along the route two miles ahead of the load. When the men resisted cooperating with law enforcement, the load was stopped, for fear members of the haul and the priceless mirror were in danger. Only after control was gained by Police K-9 units, was the load allowed to proceed on, this situation was resolved within one hour.
Elevation and time of the day dictated what temperature was to be expected.It was not uncommon to experience a 40 degree difference in the 7,014 foot assent in the 29 miles between base camp and the observatory. Road conditions remained clear with the occasional wet spots from natural springs and overnight condensation. On the final day, winds picked up as the load was three miles from the enclosure, blasting the mirror with a sustained 50 mph wind and gusts reaching 60 mph. The final stretch of road was the steepest grade and provided no protection from the weather. Based on the fear of an incoming storm, the decision was made for the transport team to continue on, only to find shelter from the stinging wind and bitter cold once inside the MGIO.
The dream of a working telescope became a reality in late October of 2003 when PHH delivered two major pieces of the telescope. With a mirror cell and a parabolic mirror safely inside the observatory, a sophisticated team of astronomers, engineers and riggers will assemble one side of the binocular telescope, making it operational. A much anticipated first light is expected in the summer of 2004. PHH feels privileged to be a part of this project, and is looking forward to hauling the remaining mirror cell, mirror, and bell jar to the MGIO this fall. Thanks to many months of planning, state of the art equipment, and the skills of everyone involved, the work was completed within budget, on or ahead of schedule with no incidents or accidents. (PHH received the 2003 SC&RA hauling job of the year for this project)
|PROJECT MAN HOURS
|Survey and Planning 680 hrs.
Engineering 634.5 hrs.
Fabrication 712.5 hrs.
Transport Operation 984 hrs.
|(2) Kenworth T-800’s License #AA23267, AB47195
(1) Trailking steerable 9 axle w/ load beams License #L79529, L79530
(1) Goldhofer THP/ SL (3 +3) License # M05824, M05825
(1) Caterpillar 980 wheel loader
(1) 300 ton Liebherr
(1) 140 ton Grove
(1) 120 ton Grove
|Steward Observatory, Tucson AZ. to MGIO Base Camp, Safford AZ.
|PRIMARY AND DUMMY MIRROR IN TRANSPORT BOX
|PRIMARY AND DUMMY MIRROR IN TRANSPORT BOX
|Gross weight: 307,436 lbs.
Width : 21’3″
|Gross weight: 297,436 lbs.
Width : 21’3″
|For more information and pictures, click below: