Car bomb attached to an automobile's fuel tank

About car bombs

Car bombs are a commonly used weapon for assassinations, terrorism, or guerrilla warfare. They are easy to hide, cheap to construct, and leave behind little forensic evidence. In addition, the gasoline in the automobile’s fuel tanks magnify the force of the explosion.

Where car bombs are typically attached

Car bomb explodingA well-placed car bomb is typically positioned to direct the blast toward the driver. A favorite location for car bombs is underneath the driver’s seat. Placement inside the car’s interior is not necessary however and bombs may be attached under the car’s frame or inside the driver’s side mudguard. Car bombs attached outside the car are typically magnetically affixed but may be taped or attached using clay-like material.

How car bombs are triggered

Car bombs may be triggered in a variety of ingenious ways. They may be triggered by opening of the vehicle’s doors, starting of the engine, depression of the brake or accelerator pedals, or even remotely using infrared or radio signals. It used to be common to wire the bomb to the car’s ignition but today this is considered too laborious, less effective, easier to detect, and easier to defuse.

Car bomb triggered using electrical current

Most modern day car bombs are still triggered by electrical current, more specifically, by closing or completing an electrical circuit and thereby allowing electric current to flow to the detonation mechanisms. The closed circuit is used to drive an “initiator” such as a blasting cap or a detonator. Any type of current draw, i.e. dome light coming on when the car door is opened, can be used to drive the triggering mechanism.

Car bombs triggered using a tilt fuse

By far, the most popular triggering mechanism is the “tilt fuse”, typically attached to the brake or accelerator pedal.  A tilt fuse consists of a small glass tube filled with liquid mercury (a very efficient electrical conductor) which, when tilted, completes the electrical circuit and triggers the bomb.

Remains of automobile after a car bomb explosion

Timer circuit usage on a car bomb

Car bombs may also be triggered using a timer circuit. In addition to use as a triggering mechanism, occasionally a timer circuit may be added to protect the bomber by ensuring that, regardless of the type of trigger used, the bomb cannot explode until the bomber has had time to get clear of the blast radius.

Other methods used to trigger a car bomb

Car bombs may be triggered using mechanical switches on doors, trunks, or the hood. They may also be triggered remotely using a RF remote control or a cellphone signal. Other triggering methods are not as frequently used but may include light, temperature, atmospheric pressure, or heat (using the car’s exhaust pipe).

How to defend against a car bomb

There are ways you can defend yourself against a car bomb. Firstly, always park in a public, well-lit, populated area if possible. Make sure your car is locked and windows are closed (including the sunroof). Also consider a locking gas cap.

Visually inspect the car prior to entering. Check wheel wells, bumpers, spoilers, exhaust pipes, and all framed areas underneath the car. Look for signs of fingerprints, tape, or any unusual object affixed to the car. Finally, look through the window and visually inspect the interior of the car before opening the door.

Further precautions can be implemented if needed. Place small strips of clear tape over the hood, trunk, and gas cap and check for breakage prior to entering the car. Allowing the car to become slightly dirty can help conceal the tape. To check that hubcaps have not been removed, mark the position of the hubcap with a felt-tip pen (draw on the edge of the hubcap and allow the mark to extend onto the tire).

Finally, recognize that some car bombs may be near impossible to detect. For instance, a bomb placed inside an automobile’s gas tank cannot be detected via visual inspection. You would have to look for other signs of tampering such as fingerprints or changes to any “markers” you may have placed on the car. Beside proactive steps to prevent tampering with the gas cap, sophisticated devices such as optical cameras, RF jammers, or bomb sensors would need to be used to detect well-hidden bombs.

What to do if a bomb is found

If a bomb is found, get away from the vehicle and call for assistance. Do not attempt to remove or defuse the bomb yourself. Safe removal requires specialized gear (often remote-controlled robotics). Get behind a hardened building, metal barrier, etc. A safe distance is generally considered to be 200 yards or further.

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