EMP Effects on Vehicles
by Jerry Emanuelson, B.S.E.E.
One of the most common questions about electromagnetic pulse is about the effects of EMP on vehicles. I have resisted writing much about this in the past because so little is known about it.
First, however, because it is a point of so much confusion, it is important to point out that there is no known mechanism by which a solar storm would destroy an automobile, except for making fuel unavailable due to loss of the power grid. Even the most massive solar storms are not known to contain the fast E1 component, which is the part of a nuclear EMP that can destroy items that are not connected to extremely long lines.
Astronomical gamma ray bursts that produce an huge E1 component have occurred during the history of the Earth, but the extreme rarity of a damaging gamma ray burst means that it is much less likely than a very large asteroid strike. Also, the stars in this part of the galaxy have settled into their relatively tranquil middle age; and damaging gamma ray bursts are even less likely to occur today than in our planet's prehistoric past. The only direct EMP dangers to automobiles results from nuclear EMP (and from non-nuclear EMP weapons of very limited range).
The question of EMP damage to automobiles is so complex that it cannot be answered definitely for the reasons discussed below. The one thing that does have a broad level of agreement among those who have studied the matter is that obtaining fuel after any kind of electromagnetic disaster would be a matter of extreme difficulty. Any particular vehicle may or may not run, until it runs out of fuel; then it will not run any longer until the fuel production and distribution system can be re-started.
Any statement concerning the effect of nuclear EMP on vehicles would depend upon details such as how your vehicle is oriented (in other words, which direction it is facing) with respect to the nuclear detonation. It would also depend upon the height of the detonation, the gamma ray output of the detonation, the distance and azimuth to the detonation, and the local strength of the Earth's magnetic field between your location and the detonation point.
It would also depend upon whether your car is parked outdoors, in a concrete garage, or in a metal garage. Obviously a metal garage is best, but concrete is slightly conductive and will provide a little bit of protection compared to outdoors. A major problem with any ordinary garage, however, is that any electrical wiring inside of the garage will simply act as an EMP antenna and will re-radiate the EMP inside of the structure.
There have been a number of isolated tests of vehicles in EMP simulators over the years. The manufacturers of the cars wouldn't even say which cars had been tested, and the cars were usually transported to the EMP simulators in such a way that the make and model was hidden from view. So we not only don't know the result, we don't even know which cars were tested. One Ford Taurus was tested on video by the Discovery Channel, but that was only one particular vehicle; and questions have been raised about the editing of that segment. (Having spent most of my career working for television stations and related industries, I have learned to be skeptical of television reports, no matter what the source.) Authoritative reports, however, indicate that some cars do behave like that vehicle.
The U.S. EMP Commission tested a number of cars and trucks. Although this was the most comprehensive set of tests on vehicles that has been done, those tests were very poorly done because the Commission was financially responsible for the vehicles, but did not have the funding to pay for any of the vehicles they tested. The vehicles were borrowed from other government agencies (most vehicles came from the Department of Defense); and the vehicles had to be returned to those lending agencies in good condition.
Those vehicles were tested up to the level that some sort of upset occurred, then further testing was stopped on that vehicle. In most cases, after the initial upset occurred, the vehicle could be restarted. In most of the remaining cases where the vehicle could not be immediately restarted, a latch-up had occurred in the electronics, and the battery could be momentarily disconnected to "re-boot" the electronics, and the vehicle could then be restarted. This temporary electronic latch-up failure mode caused by EMP is something that almost never occurs in automobiles during a typical lifetime of operation.
Only one of the vehicles tested (a pickup) could not be restarted after some minor work, and it had to be towed to the shop for repairs.
Very few of the vehicles were tested up to the maximum level of the EMP simulator. There was considerable disagreement among Commission staff members about how to report on the testing that had been done. Some EMP Commission staff members believe that the wording of the paragraphs in the EMP Commission's Critical National Infrastructures Report about the effect of EMP on vehicles is quite misleading.
For an excellent audio discussion the testing done by the Commission on automobiles and trucks, listen to EMPact America Radio Program number 41, which contains a discussion of this matter between the Chairman of the EMP Commission and a prominent staff member of that Commission.
In particular, the discussion about the testing of vehicles was roughly between the 46 minute and 54 minute marks of this 96-minute program.
The following quote is the report on the EMP Commission testing of vehicles from pages 115-116 of the EMP Commission Critical National Infrastructures Report:
It is important to note that the latest model of car that was tested by the U.S. EMP Commission (as noted in the quotation above) was a 2002 model car. Since 2002, the number of microprocessors in cars and the reliance on microprocessors in all motor vehicles has increased greatly. Also, the sensitivity of the electronic circuitry to EMP has increased due to the use of smaller electronic components designed to operate on lower voltages.
Automobile manufacturers have also done EMP testing on their own at the EMP simulator at the White Sands Missile Range in New Mexico. There was a news release from the White Sands Missile Range web site about this testing. Since that White Sands statement disappears from the web occasionally, I have reproduced it below.
Today's automobiles have published standards for electromagnetic shielding, but there is not much consistency in shielding requirements. You can check this list from Clemson University for a partial list of the many and varied standards for electromagnetic shielding of automobiles. Most automobiles and trucks have a similar appearance, at least close enough that we can tell when a object is an automobile or a truck just by looking at it. When it comes to wiring and electronics, however, the differences are much more striking. This fact makes generalizations about vehicles and EMP very difficult. Even if every make and model were tested on one occasion in an EMP simulator, the EMP resistance could be changed dramatically just by moving a wire or by changing the way that a cable is routed. This makes statements about the EMP resistance of any particular make and model nearly meaningless. This is why you will not find a listing anywhere of which makes and models of vehicles are EMP resistant.
As I pointed out on another page on this web site, retrofitting an automobile to make it EMP-resistant is a project that would be too difficult and expensive for most people. For those who want to try, the only authoritative document that I know to be available is one called "EMP Mitigation - Protecting Land Mobile Vehicles from HEMP Threat Environment" which was just published in March, 2011. To find this document, go to the Protection Technology Group page, then click on the Knowledge Base link at the top of the page. Scroll down on the Knowledge Base page until you get to the article that you want. The article specifically applies to military vehicles, but has relevance to commercial vehicles as well. Note that the part of the referenced article that refers to bonding of "all metallic structures to a single point ground system" is referring to an electrical chassis ground on the vehicle, not to an earth ground.
Some additional suggestions for making vehicles more resistant to EMP can be found on pages 118 and 119 of EMP - Protect Family, Homes & Community, 3rd edition by Don White and Jerry Emanuelson.
The easiest way to retrofit some EMP protection into an automobile is to use the snap-on ferrite cores described in the EMP Personal Protection Page. These snap-on ferrite cores can be snapped on over all kinds of unshielded bundles of electrical wiring in an automobile or truck. You will have to go through the wiring on your automobile thoroughly to determine the size of the snap-on ferrite core that you will need to order. So this will involve going through an inspection of your car's wiring twice: once to measure the size of each bundle of wires, and again to install the snap-on ferrite cores after your order arrives. The snap-on ferrite suppression cores are not a perfect solution. They will only help to suppress (but not eliminate) fast voltage transients on the bundles of wires that are accessible to you.
I also must re-emphasize the fact that during Soviet high-altitude nuclear tests over Kazakhstan in 1962, rugged diesel generators having no solid state parts were burned out by E1 EMP. In an important international electromagnetics conference in 1994, after the breakup of the Soviet Union, General Vladimir Loborev delivered an important technical paper in which he stated, "The matter of this phenomenon is that the electrical puncture occurs at the weak point of a system. Next, the heat puncture is developed at that point, under the action of the power voltage; as a result, the electrical power source is put out of action very often." This illustrates that even vehicles without an electronic ignition or other electronic components are not immune from EMP.
The main advantage of a well-maintained older vehicle may be that it is likely to be much easier to repair if it does sustain EMP damage. The Soviet experience is a warning to keep critical electrical spare parts on hand for the older vehicle. This includes things like ignition coils, mechanical distributors, generators and starting motors. In particular, any critical item with a coil of wire that is insulated using enamel or a similar substance may be prone to breakdown, and needs to have a replacement part on hand. Also, as I have said on other pages, a good supply of automotive fuses is also critical.
The worst thing about nuclear EMP and motor vehicles is if you happen to be driving in heavy traffic when it happens. In this event, simultaneously, a certain percentage of vehicles will stop running (perhaps temporarily), many more drivers will be instantly and simultaneously distracted by strange electrical behavior happening inside of the car, and (at the same instant) the traffic lights will abruptly go out or go into a flashing mode. This instantly creates the worst traffic jam in history in certain localities, and vehicular accidents at some busy intersections are likely to be severe or fatal. If you have an working motor vehicle in a post-EMP situation, there may not be any clear roads to drive on.
Perhaps the most important question to ask yourself is where you are likely to be going after a nuclear EMP event. If you live in a fairly secure area, the best choice may be not to go anywhere at all for a very long time. If you live in a less secure area, and know a more secure location where you can stay, you need to think through as many scenarios as possible in advance of the event. If you plan to go to the grocery store after the EMP to purchase emergency supplies, one second after the EMP event will be too late. The grocery stores will be closed for a very long time, starting at the instant that the EMP hits and disrupts the inventory control system and the data processing systems that handle payments. It is also very likely that the electrical power will be out as well.
More important than fuel for your car is fuel for yourself. If we are unfortunate enough to experience a nuclear EMP attack, many people will starve to death or will die from lack of critical medications while they have a perfectly functioning automobile in their driveway. When it comes to surviving disasters, it is imperative to calmly think through what is really important.
Finally, it would be appropriate here to say something about the effects on vehicles of the real nuclear EMP tests that were done in 1962. There have been reports of damage to automobiles in both the United States and Soviet high-altitude tests in 1962. Those reports were all unconfirmed verbal reports, and the verbal reports were made many years after the events. In addition, problems with the electrical ignition system were one of the most common causes of automobile problems in the early 1960s, so it is impossible to know whether any vehicular problems that occurred at about the same time as the high-altitude nuclear tests were actually related or were just coincidence. I tend to think that they were just coincidence. The Soviet military diesel generator problems were definitely related to the nuclear tests, although those diesel generators were probably connected to long external wires during the nuclear tests. (The Russians have not shared many details about this.)
Since we know that EMP can punch through electrical insulation, especially on things like motor and generator windings when they are connected to external wiring, it is certainly plausible that damage could occur on vehicular electrical systems even if the vehicle contains no solid-state electronics. The plausibility of this sort of damage in a future EMP is higher when one realizes that the EMP field strengths that were experienced in populated areas in the 1962 tests were only 10 to 20 percent of what could be experienced with known nuclear weapons.
In particular, in the United States Starfish Prime event in 1962, the maximum electric field pulse experienced in Hawaii was in the range of 5,000 to 5,600 volts per meter. The worst EMP effects of the Soviet tests over Kazakhstan were about 7,500 volts per meter in the area where problems were actually documented. The EMP may have been as high as 10,000 volts per meter in un-monitored areas of Kazakhstan, but not any higher. We know that it is possible to rather easily generate 50,000 volts per meter with an old second-generation nuclear weapon of the proper design. There are reports that may be possible to make nuclear weapons that will push beyond this 50,000 volts per meter limit.
An EMP of 50,000 volts per meter would undoubtedly damage some cars, both with and without solid-state electronics. What percentage of vehicles would be damaged, and which particular vehicles would be damaged, is something that even the best EMP experts can only make guesses about. The total available data is just too limited, and the number of variables are huge.