FORT KNOX, Ky. -- Sgt. 1st Class Daniel Carpenter steers and watches in a mirror as 65 feet of steel- on-wheels pivots, then inches to a passable distance from a row of bright orange parking cones. The West Virginia native has just parallel parked a semi-trailer, one of the toughest tasks on the test to gain a commercial driver's license (CDL) and the option of a high-paying job after leaving the military service.The Army's only in-house CDL program trains Soldiers to operate a fleet of semi tractors and trailers that serve as rolling billboards for Army outreach efforts. Soldiers who complete the training work as exhibitors on semi tractors and trailers with interactive displays and content that helps connect America with America's Army. The Soldiers and training program are part of the Mission Support Battalion at Fort Knox, Kentucky. The Mission Support Battalion is part of the United States Army Marketing and Engagement Brigade."The CDL course has been called one of the Army's best-kept secrets," said Mission Battalion Commander, Lt. Col. Mario Washington. "The training has been remarkably effective in producing the trained Soldiers we need to keep a vitally important Army mission on the road nearly 365 days a year."Mission Support Battalion began its CDL program three decades ago to make sure that Soldiers had the right skills and training needed to safely operate the big rigs. The program has since been hailed as an example of how the Army can use its own resources to provide high quality training. Leaders point to statistics as proof. In 2016, battalion Soldiers drove more than 750,000 miles across the continental U.S. without any major accidents.The program has been so successful that the Mission Support Battalion wrapped up a pilot program in 2016 that opened the training to veterans exiting the military service to provide a skill that Soldiers could market in the civilian life. About four classes, or 20 students, graduated from the program that included partner organizations such as the Mission Support Battalion, the Army Career Skills Program and a regional civilian transportation company R&R Trucking. Soldiers exiting the service received training needed to gain a CDL they can use for employment after the military. Under the partnership, R&R Trucking offered jobs to Soldiers who successfully completed the training and obtained their commercial driver's license. Driver teams can make more than $120,000 a year, according R&R trucking figures. The program's future, to include possible Army-wide application of the program, is under evaluation by pilot partners.Soldiers traditionally do not require a CDL to operate large military vehicles and can be licensed by their commander, CDL course instructor Frank Gainer said. However, to ensure that Soldiers assigned to the Mission Support Battalion were well trained to drive commercial semis, leaders decided to institute the training with a focus on safety.The course is just as rigorous as similar civilian courses offered off-post, according to Gainer. That includes the commercial driver's license test. For example, obtaining a driver's license through the Fort Knox program requires passing an examination administered by Kentucky State Police troopers who make sure applicants perform safety checks, can maneuver a semi-trailer, and can navigate traffic with an 18- wheeler.Training and practice to avoid obstacles and successfully parallel park the trailer marks mid-point in the CDL training program, Gainer said.Students have to maneuver a semi tractor-trailer through a course of traffic cones, he said. Classes average from five weeks in length."There are three parts to the training program," Gainer said. "The first is the pre- trip inspection. The second part is the student's ability to drive around obstacles. The third part is the actual road test and driving in traffic. Students have to make a certain number of left and right turns, show how to enter the highway properly and how to cross the railroad tracks." Carpenter walked through phase one of the training course, performing preventive maintenance checks on the semi-tractor's diesel engine."The Kentucky State Policeman that tested me said that the training we get is 10 times better than what the civilians get. We actually go step by step."Key to that emphasis is safety for the semi driver and other motorists, Carpenter said. "I've driven trucks with trailers before and the toughest thing is to remember that you have turn the steering wheel in the opposite direction of where you want to go when backing up. You have to take a second or two to think about what you're doing, then realize that you have a 65-foot trailer behind you."Carpenter will be staying on active duty to drive one of Mission Support Battalion's outreach vehicles. As a veteran looking at retirement he said the training has real value for after the service. "It's a good fall back for me," Carpenter said. "After retirement I will have a skill I can use."