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Vehicle Hardening

As the nature of conflict changes, so does the threat to logistics units. War and certain other operations--especially peacekeeping or peacemaking--place renewed emphasis on convoy security and reinforce lessons learned in Vietnam. Current threats include the use of command-detonated and pressure-sensitive mines placed on, above, or along the shoulders of roads traveled by military vehicles and the ambushing of convoys and harassment with sniper fire. These methods of disrupting military operations are highly effective, cheap, require limited time and labor, are easy to coordinate, and can be accomplished by an unsophisticated enemy.

To counter these threats, motor transport units may be provided with security forces and supporting arms firepower. Also, special vehicle-hardening techniques using sandbags and other improvised material have proved successful in protecting convoy personnel, equipment, and cargo. This appendix describes these techniques. Although effective, vehicle-hardening techniques must be tailored to fit the specific environment in which the motor transport units are operating.

A hardened vehicle is made less vulnerable to the effects of explosives and small arms fire by adding sandbags, armor plating, ballistic glass, and other protective devices. Hardening may make certain vehicle components and cargo less vulnerable. Its primary purpose, however, is to protect the truck's occupants. The protection afforded is significant and often means the difference between injury and death.

The vehicle hardening techniques described here include locally fabricated (improvised) armor kits and sandbags. When an enemy threat exists, consider the following factors in determining the method and extent of vehicle hardening:

  • Flexibility. Harden vehicles to provide the degree of protection required while maintaining maximum flexibility in vehicle use. Harden the cargo beds of vehicles carrying troops with sandbags. Beds of vehicles carrying cargo are not normally hardened (depending on the cargo).
  • Weight. All vehicle hardening adds weight to the vehicle. One effect of added weight is to reduce proportionally the amount of cargo that can be carried. Another potential effect is added vehicle maintenance and durability problems. Consider the vehicle's payload capacity when deciding the extent of hardening.
  • Availability. If it is necessary or desirable to fabricate armor kits, consider the availability of suitable materials and the time needed to complete the project.
  • Types of roads. To some extent, the roads traveled by motor transport unit vehicles can affect the protection required. Hardtop roads, for example, generally present less hazard from mines than dirt roads. However, do not discount the possibility of ambush along any route. Consult the S2 for the most current information on the situation.
  • Maintenance. Vehicle hardening normally increases the amount of vehicle maintenance needed and can cause mechanical or structural damage. The sandbags themselves, when used to harden vehicles, also require periodic removal and replacement. If too much weight is added to the vehicle, it may reduce the vehicle's mobility and operational capabilities.

During Vietnam, the Army had three nonremovable armor kits for hardening 1/4-, 2 1/2-, and 5-ton trucks. These kits were later deleted from the inventory. Although no kits are currently available through the Army's supply system, several projects are under way to develop armor plating for use in hostile environments.

  • Level one means that the vehicle cab was built in the factory with a much higher level of armor protection. And that's important, because it means from the start that vehicle was designed to operate with many more pounds of armor than the original vehicle may have been designed to operate. So it's essentially an all-encompassing armored solution, and it's our very, very effective solution. Level one, departmental approved integrated armor means that the cab on this medium truck was designed in the factory and made in the factory and installed on that piece of equipment -- is an armored cab.
  • Level two force protection puts additional protection on vehicles that are already in use out across the Army's inventory. That has been the other principal focus the Army has in Iraq. It can't automatically or magically swap out all of the equipment that we have out in the theater, but what they can do is develop programs where we take kits and put them onto existing pieces of equipment. This is not a trivial process, since a lot of testing that goes into these level two kits, so that we put the right things on pieces of equipment to make sure that the actual system can continue to operate with many thousand more pounds on it, in some cases. For example, for a humvee, the typical add-on armor kit is just over a thousand pounds. It would have secondary impacts in terms of your suspension and your powertrain. The Army had to test those things out to make sure that they were giving a soldier something that can endure in combat; it won't just break the minute he starts to operate it. So the level-two kit is a sophisticated requirement and one that has been very successful in adapting, not just for humvees but, for a variety of systems. Templates have been designed in part by the drivers who operate the equipment, with Defense Logistics Agency-approved steel being used. The level-two humvee kit has materials that have been designed by the department, tested by the department and then moved to installation sites. It takes somewhere around 30 or 40 hours of labor it takes to put one of these kits on a humvee.
  • Level three is locally fabricated armor. Initially in Iraq the designs were primitive and there were problems with materials. Typical level-three efforts that are done in the combat zone are hardened doors, hardened side posts, additional protection here underneath, on the side of the vehicles, all of it designed to make it more resistant to enemy attacks. So what this does is dramatically decrease the risk of the operator, but it's not the same total encompassing solution as in a level-one kit.

Sandbags are effective in reducing the effects of blasts, preventing fire from reaching the driver, and providing protection from small arms fire and fragmentation. Sandbags are usually readily available and do not permanently impair the flexibility of vehicles. Sandbags can easily be added or removed from the vehicle as the situation dictates. One drawback to using sandbags is that their weight limits the vehicle's capability to haul cargo.

Hardening vehicles with armor plating places abnormal stresses on the vehicle that can result in early component failure. It is common for engine mounts, cab mount bushings, and bolts to loosen. For this reason, they should be checked, tightened, and replaced regularly. In the past the vehicle deadline rate for hardened vehicles was up to 20 percent greater than for nonhardened vehicles.

Sandbags become torn or punctured in day-to-day use. They also collect and hold water, causing metal surfaces to rust. Added maintenance is required to keep the sandbags in good condition and to prevent rust. Sandbags should be checked periodically and removed or replaced. When the sandbags are removed, the vehicle metal should be cleaned, painted (if necessary), and allowed to dry before the sandbags are replaced. Empty sandbags and ties should always be kept in the vehicle.

It is critical that the most protective material available be used to harden a vehicle. Ballistic tests show that sand is about twice as effective as clay in hardening vehicles. At a maximum velocity of 3,250 feet per second at a range of zero feet, it takes about .6 feet of sand and 1.2 feet of clay to stop a 5.56-mm round. At a maximum velocity of 2,750 feet per second, it takes about .9 feet of sand or 1.7 feet of clay to stop a 7.62-mm round. Finally, at the maximum velocity, it takes about 1.4 feet of sand or 2.6 feet of clay to stop a 50-caliber round. Using the most protective substance could mean the difference between life and death for the most precious resource -- soldiers.

Logistical convoys cannot always depend on military police support or added firepower. To provide more firepower for a convoy, units developed the gun truck. The purposes of a hardened gun truck are to provide a base of fire; help counter enemy attacks, and increase survivability of the convoy. The gun truck is equipped with a crew-served weapons system, preferably in a protective position. In Vietnam this principle worked well and provided convoys a means of self-defense.

Commanders deploy the gun truck in the convoy where it can best provide the needed firepower. If adequate communications assets are available, they should be located with the gun truck and the convoy commander. This enables the convoy commander to call the gun truck forward when needed. A predesignated signal is required to bring the gun truck forward and inform the crew-served weapon system personnel of the enemy location. If communications assets are not adequate, pyrotechnics may be used to signal the gun truck to move forward.

The gun truck should not be pulled up right on top of the enemy location. The crew-served weapons on the gun truck can cover a significant distance. Therefore, the vehicle should be situated where it has a clear field of fire to engage the enemy with the maximum effective range of the weapon. If necessary and if available, multiple gun trucks can be used. When using multiple gun trucks in a convoy, overlapping fields of fire greatly increases the convoy's chance of survival.

As of December 2004 the Army was postured to project 35,000 vehicles to be up-armored. This was the validated requirement funded from theater. Of that 29,000 were currently funded. There were also plans for additional for a total of 38,000 vehicles.

Cab mounts is a good example, for medium and heavy trucks, of an item that had to be redesigned for up-armored vehicles. Cab mounts were designed to hold a cab that was much lighter, and after strapping armor on top of it, the cab mount in many cases, had to be beefed up because of failure rates on the cab mounts, and that's a significant effort to do those kinds of things. With the medium/heavy tactical wheeled-vehicle fleet, generally those trucks are designed to carry and haul loads and their speed is not affected with the kits. But fuel consumption is indeed a point that has grown.

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