Airtight seal skins inspire rolligons
Traditional knowledge of Alaska Natives yields secret of technology to California inventor; Crowley provides service for 30 years
For Petroleum News
June 20, 2007, marked the 30th anniversary of the first barrels of North Slope crude flowing down the 800-mile trans-Alaska oil pipeline from Prudhoe Bay to Valdez. Looking back, it is clear that the role of technology has been paramount in the progress operators and contractors have made in improving the efficiency and lessening the impact of their operations on the Arctic environment. In a series of seven articles, Petroleum News will report on some of the technologies developed by the dedicated and innovative men and women who work on the North Slope. These articles will be followed by “30 Strong,” a full color magazine celebrating three decades of North Slope oil production.
To explore for and develop petroleum resources on Alaska’s North Slope, engineers had to build an infrastructure that would disrupt the region’s permafrost as little as possible.
Part of the answer for travel across the fragile tundra is the technology underlying the transportation innovation commonly referred to as rolligons.
But the premise for rolligon technology dates back to the first men to visit the Arctic.
The rolligon’s inventor, William Albee got his inspiration while visiting Alaska on a fishing trip in 1950.
Albee observed a group of Alaska Natives preparing to remove a heavy wooden boat from the Arctic waters. He wondered how the small, heavily clad men would transport the boat up the muddy bank. The Natives produced and inflated several airtight seal skins and rolled the boat onto them, out of the water and up the bank.
Thus was born the concept of the Rolligon low pressure “air bag.” Albee returned to Monterey, Calif., and began to develop the first low-pressure, off-road tire. He also formed the Albee Rolligon Co. to produce vehicles equipped with the low pressure tires.
The first tires were smooth and driven by a top roller, another Albee Rolligon innovation. They measured 30 inches in diameter and 40 inches wide. Albee Rolligon obtained patents on both the wide, low-pressure tire and the top roller drive.
Rolligon changes handsBut Albee was unable to develop his concept into a successful business. He sold the assets of his company to John G. Holland Sr. in 1960. Holland moved the business to Houston, Texas, where he owned and operated a highway-heavy construction company. He incorporated his new assets under the name of Rolligon Corp. and his two companies shared an office, warehouse, and yard.
Rolligon Corp. built several top roller vehicles; however, it was apparent that while the top roller vehicles operated well on sand and level, vegetated terrain, they did not perform well on muddy or wet, inclined surfaces.
Rolligon then vulcanized lugs on a 40-inch-by-50-inch smooth tire, and designed a 4x4 vehicle with axles directly driving the tire from the center. The vehicle was fitted with a pivot and steering was accomplished by articulating the frame. This 4x4 became the model 4450 Marsh Skeeter. It was lightweight, amphibious, and highly mobile and exhibited a ground-bearing pressure of less than 2 pounds per square inch.
With the success of the 4450 came requests for bigger payload capacity vehicles. So Rolligon then developed a 6x6 vehicle, Rolligon Model 6650, along with a larger 54-inch-by-68-inch tire.
In the late 1960s, Rolligon entered a joint venture with the Bechtel Corp. of San Francisco to manufacture several 12x12 vehicles for use in the new oil fields on the North Slope. The vehicles were designed with the 54-inch-by-68-inch smooth tires designed to exert low pressure on surfaces, specifically around 3 psi. They had top roller drives rather than direct drives and 8x8 tractors with four-wheel-powered trailers. Their large, low-pressure rubber “air bag” tires enabled them to essentially float across unpacked snow, summer tundra, sand and marshland. The tires help distribute the weight of the vehicle and its payload over a large area, thus minimizing terrain impact.
Though they exert higher surface pressure than hovercrafts, rolligons still exert relatively low pressure, low enough for the U.S. Department of Energy to call them an “ultra-low impact vehicle.” Rolligons carry a maximum payload of 30 tons and travel at maximum speeds of about 20 mph, making them ideal for carrying small drill rigs and drilling platforms.
Crowley actsSix of the vehicles were delivered to Alaska in 1968. Another 12 were built in 1974 and the newest ones were built in 1980, according to Don Tunks, Crowley All-Terrain Corp.’s manager of operations and maintenance.
Crowley Maritime Corp., CATCO’s parent organization, purchased the North Slope transportation venture in 1975 and still operates the original vehicles on the slope today, providing oil field services. Rolligon Corp. continues to manufacture tires for the vehicles.
The name Rolligon actually applies to a much smaller vehicle used for seismic work and refers specifically to the tires on the vehicles. Even though CATCO’s machines are commonly called Rolligons, technically CATCO cannot use that name.
“We call them units or vehicles,” explained Tunks, who came to the North Slope more than 30 years ago.
“I came here in ’74,” Tunks says. “There wasn’t much here; a couple of ATCO units for the airport terminal. There were very few people, and I don’t remember any women. The road went from East Dock to the Kuparuk River and stopped. On the other side it went to Service City, but it didn’t cross the river.”
Referred to by some as the “Neanderthals of the North Slope,” CATCO’s camps are vintage 1970s.
Crowley dubbed its specialized vehicles CATCOs. The company’s 29 units are the only ones like them in the world. They operate virtually the same as they did when they first arrived on the North Slope, with two exceptions: The units have been equipped with cell phones and GPS navigational aids.
Before the advent of rolligons, early operators on the North Slope used Cat trains to move supplies and equipment across the tundra. The practice was discontinued because of the detrimental effect the vehicles had on the tundra.
In 30 years, Crowley has developed a unique system for transporting cargos and personnel to remote roadless areas that has little if any effect on fragile tundra.
Peak Oilfield Services also operates the same type of vehicle on the North Slope today, but its vehicles are called Tundra Cats and Rimpulls.
“From the marine side, we call them ‘land barges’ because of their large 16-foot platform” said Craig Tornga, Crowley’s Alaska manager.
These “land barges” are used to build ice roads; transport drill rigs, fuel and supplies; and even construct ice pads in extreme locations and conditions.
A return to track vehiclesDuring the past few years, some North Slope contractors have taken to using tracked equipment for transporting goods and equipment across the tundra. But the tracked vehicles of today use a track made of rubber instead of steel.
Still, the tracked vehicles have a much greater impact on the tundra than rolligons, with a higher likelihood of tundra damage, according to Peak officials.
Also, others are using vehicles with the large tires, but instead of a smooth tread and a roller drive, these have a direct drive and tires with a chevron tread pattern.
This type of tire also has a greater impact on the tundra.
“When the vehicle gets stuck, the wheels start to spin, which damages the tundra,” said a Peak official who asked not to identified. “We feel this increased use of non-rolligon-type vehicles will continue to cause damage to the tundra.
“This lack of environmental consciousness and shortsightedness in continuing to use these vehicles is going to risk the future of remote exploration,” he added.