|HEAVY HITTERS The Corps of Engineers is combining high technology and heavy equipment to speed battlefield airstrips.|
Two dozen combat engineers arrive on a remote, abandoned airfield at midnight. They are equipped with night-vision goggles, a couple of laptops, satellite communications gear and a few pieces of earthmoving equipment. In a brief period of 12 hours, they map out the terrain, analyze the soil, generate 3-D digital designs and specify construction procedures. A motorized scraper guided by global-positioning satellites begins clearing grub. A day and a half later, the airfield is ready for minimal traffic.
Such a feat would usually take a team at least a week to complete. But the U.S. Army Corps of Engineers is trying to cut design and construction schedules during combat by at least 50%. As a result, under way is a $23-million, six-year research project called Joint Rapid Airfield Construction. The Corps demonstrated JRAC's capabilities to private vendors, Pentagon officials and other engineers in the armed services July 14-15 in Ft. Bragg, N.C.
Alongside an existing 3,500-ft-long, unpaved runway, soldiers built two 40,000 sq-ft aprons, or parking spaces, for 175,000-lb, C-130 transporter aircraft in only three days. The trapezoidal aprons measured 300 ft on the long side, 100 ft on the short side and 200 ft on the tapered sides. The aprons allow planes to clear the runway so others can land and take off safely.
Interest in JRAC gained momentum after fighters faced airfield-maintenance challenges on an austere outpost's dirt runway during the Afghanistan conflict (ENR 2/25/02 p. 20). The first main goal of JRAC is to support C-130 aircraft within two days by putting into service what the Army and Air Force call a "contingency airfield," one that is either abandoned or captured, then reconstructed to handle plane traffic during battle.
A final demonstration in 2007 will take the project to a next critical objective: contingency support for heavier, 447,000-lb, C-17s, within the same 48-hour time requirement. In an effort to validate methods and develop standard construction protocol, the Corps is sharing its research with other services and asking for their input.
The project has become a top military priority because "it directly affects the warfighters," said Col. James R. Rowan, commander of the Corps Engineer Research and Development Center in Vicksburg, Miss., where the JRAC team is based.
The program uses off-the-shelf products, such as geospatial software and soil-stabilizing polymers, to push military construction to warp speeds. The work is part of a bigger transformation happening within the Army to increase its combat mobility. The U.S. still depends heavily on allied air bases to launch attacks. But the face of global warfare is changing. Army officials reflecting on the remotely-located Afghanistan and Iraq conflicts say they must develop the capability to deploy troops to a distant site in 10 days, defeat the enemy in 30 days and relocate to another fight in 30 more days.
"Our challenge is to go anywhere in the world," said Gary Anderton, civil research engineer and JRAC program manager. "Once an airfield site is selected, it must be operational in 48 hours. Any longer than that and it wouldn't be considered rapid."
The process is fast and furious. On July 12, soldiers from the XVIII Airborne Corps, 20th Engineer Brigade and 412th Engineer Command arrived on site at midnight and began surveying. They had not visited the site prior to the exercise. Their gear included night-vision goggles, GPS tools and Toughbook laptops programmed with geospatial software.
Heavy equipment included a Caterpillar-made Army dozer, an elevating scraper, a motor grader, a $250,000 Terex reclaimer-stabilizer, a skid-steer loader and a prototype machine called a Rapid Assessment Vehicle Engineer (RAVEN) based on Bobcats commercially-available Toolcat utility vehicle. Anderton noted that operators received about three days of "stick time" to train themselves on the machines.
|The Rapid Assessment Vehicle Engineer (RAVEN) is based on Bobcat's commercially-available Toolcat platform introduced at World of Concrete 2003 in Las Vegas.|
RAVEN is a unique vehicle that cost the Army roughly $175,000 to build. It is air-droppable via parachute. Once deployed, it roves the jobsite, with or without an operator, to acquire GPS plot points every two meters. The data is imported into a geospatial database that is linked to 3-D design software. In its rear cargo area, the machine is fitted with a mobile soils-testing laboratory hooked up to a database of soil profiles around the world. The machine also has an articulating arm in front that handles multiple attachments, including an automatic, hydraulically-actuated soil pentrometer, a hammer-like device that measures the load-bearing strength of compacted earth.
The topographical design process was paperless. After data collection, soil analysis and 3-D plans were complete (that took 12 hours for each apron) the information was imported into GPS computers mounted in the cabs of the heavy equipment. Each machine had a digital Trimble controller piped into the hydraulic circuits that control the blade. All the operator has to do is steer the machine, according to Anderton. Surveyors programmed the sites cut and fill requirements and did not use ground stakes as reference points. But it wasn't a perfect system. "We still had a couple of hiccups," said J. Kent Newman, JRAC physical scientist in charge of soil stability. "The cut and fill was off a bit, and that increased our construction time."
|Inside RAVEN, an engineer prepares a 3-D site design file|
Engineers stabilized the ground on one apron using a 6-in.-thick topcoat of 3% Portland cement and 3% liquid polymer. The materials were tilled into the soil using the reclaimer-stablizer machine. On top of the mix were 580 interlocking mats made of fiberglass polyester and measuring 6 ft. square. The second aprons topcoat featured an 8-in. lift of 4% Portland cement and 0.2% of 2-in.-long polypropylene fibers. The mix was sealed on the surface with a liquid polymer for moistureproofing and dust control. The first apron was complete within 48 hours; the second was ready after another 24 hours had passed. Both were designed to withstand 750 cycles of C-130s and achieved strength ratings of 500% to 600% higher than before.
Thomas Manley II, vice president of government affairs for Terex Corp., Westport, Conn., says that Andertons team is "pioneering what is required for the military in terms of expeditionary construction." But similar to how automatic GPS grading is now migrating into military useseveral years after earthmoving contractors began taking it on in the late 1990sit is likely that other JRAC innovations will find their way into the private sector as well. Says Travis A. Mann, civil research engineer and digital technology expert for JRAC, "To have guys moving dirt in 12 hours" after site selection, "thats an unbelievable feat."
(All Photos by Tudor Hampton for ENR)