Beginning in 2003, USAP initiated a four-year effort to develop a heavy-haul traverse to resupply South Pole Station from McMurdo Station. Four rubber-tracked tractors and one bulldozer towed steel sleds carrying fuel, cargo and support modules directly over unprepared snow. This proof-of-concept effort established a 1030-mile safe route across the Ross Ice Shelf, up the Leverett Glacier, and across the Polar Plateau to South Pole (Wright 2006). It also made the first modest over-snow resupply of South Pole Station.
Engineers at the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) supported the proof-of-concept effort via numerous safety and mobility studies. Importantly, this USAP–CRREL partnership developed high-efficiency fuel sleds consisting of flexible fuel bladders strapped to flexible sheets of high molecular weight polyethylene (HMW-PE). Compared to steel sleds, the bladder sleds are one-sixth the cost, are one-tenth the weight, and triple the fuel delivered per tractor to South Pole.
The South Pole Traverse (SPoT) became an operational department of USAP in 2007, and during the 2008–09 season, it conducted the first large-scale over-snow resupply of South Pole Station. SPoT repeated this success in 2009–10 and 2010–11. During these three seasons, the SPoT fleet of eight towing tractors delivered an average annual payload of 768,000 lb to South Pole, most of which was fuel towed in bladder sleds. These deliveries offset an average of 30 annual LC130 flights to South Pole and achieved a net economic benefit of $2.0M/year
Based on this success, USAP expanded SPoT to include a second eight-tractor fleet (SPoT2) and added traverse fleets to support science camps on the Pine Island Glacier (PIG) in West Antarctica and the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) on the Ross Ice Shelf. NSF-PLR also initiated the Greenland Inland Traverse (GrIT) to re-supply its science stations on the Greenland ice cap from Thule Air Base