|
State adds vehicle to tundra travel list Polaris Ranger models tested for North Slope summer off-road travel at request of ConocoPhillips; 6X6 model fares better than 4X4 Kristen Nelson Petroleum News
The Alaska Division of Mining, Land and Water has tested two new vehicles for summer off-road travel on the North Slope, approving one.
The division said that at the request of ConocoPhillips Alaska it tested the Polaris Ranger XP 4X4 800 and the Polaris Ranger 6X6 800. The company was looking at different vehicle types and sizes to support varying off-road infrastructure maintenance activities, the division said in a May 25 memo. The role for the Ranger would be to transport workers and light-duty equipment for jobs requiring smaller tools and fewer personnel.
The Polaris Rangers are lightweight side-by-side off-road vehicles designed for light duty work, the division said, with both tested models including a rear storage box.
After testing, the 6X6 was approved; the 4X4 was not.
Testing In tests the vehicles were driven around adjacent modified figure-eight paths situated such that one end was on wet tundra and one end on relatively dry tundra, with the straight section in the middle on moist sedge dwarf shrub tundra. Each vehicle made five passes with soil moisture and active layer data collected after the tests on the adjacent vehicle routes and an undisturbed control area.
Observations were made by ConocoPhillips representatives and division staff.
The 4X4 produced minimal disturbance in the straight section, but the division said tussocks and moss “were torn more significantly” than by the 6X6 with vegetation matted after several passes and a minor degree of rutting.
There was minimal tearing of vegetation and no ruts present in the dry tundra turn area, but results were different in the wet tundra area, which the division described as “very wet prior to testing.”
“A thick slurry of organic material, suspended soil particles, and water formed after a few passes. Tires were visibly spinning thru the wet section and vegetation was removed, with a degree of uprooting present,” the division said.
The division said the tundra damage from the 4X4 test was expected to persist for several years, but said the tundra was expected to recover without additional measures.
6X6 test The 6X6 produced minimal disturbance in the straight section of the test, which transitions from fairly dry to fairly wet tundra, with some vegetation matting but no rutting. In the dry tundra turn area there was “no tearing or scuffing of the vegetation and no ruts were present.”
In the wet tundra portion of the test, described as “very wet prior to testing,” the track was immediately visible after a single pass by the 6X6, with vegetation matted down. After the final pass, organic material and soil particles were suspended in about 6 inches of standing water.
The division said some vegetation was removed, “but there was no sign of vegetation being uprooted and rhizomes were still intact.”
“It is believed that this area will recover well during the following summer,” the division said, and noted that off-road travel permits require “areas like the wet tundra turn should be avoided.”
“Overall, the disturbance levels were acceptable,” the division said.
The test areas will be re-evaluated this summer, a year after initial testing.
The division said the Polaris off-road vehicles appear to be good selections for light-duty off-road tundra travel, with group consensus that the 6X6 “performed to a higher standard, perhaps as a result of better weight distribution than the 4X4,” with the 6X6 showing little to no tundra disturbance on all soil moisture gradients tested while the 4X4 showed signs of rutting and a significant level of disturbance in wet tundra.
In approving the Polaris 6X6 for summer tundra travel the division noted that it can provide for the same off-road light-duty needs as the 4X4, while operating in the summer with less impact on the tundra.
Information on vehicles previously approved for off-road summer tundra travel and requirements for tundra travel permits are available on the division’s website at http://dnr.alaska.gov/mlw/factsht/off-road_travel.pdf.
| 