Automobiles
The potential EMP vulnerability of automobiles derives from the use of built-in electronics
that support multiple automotive functions. Electronic components were first
introduced into automobiles in the late 1960s. As time passed and electronics technologies
evolved, electronic applications in automobiles proliferated. Modern automobiles
have as many as 100 microprocessors that control virtually all functions. While electronic
applications have proliferated within automobiles, so too have application standards and
electromagnetic interference and electromagnetic compatibility (EMI/EMC) practices.
Thus, while it might be expected that increased EMP vulnerability would accompany the
proliferated electronics applications, this trend, at least in part, is mitigated by the
increased application of EMI/EMC practices.
We tested a sample of 37 cars in an EMP simulation laboratory, with automobile vintages
ranging from 1986 through 2002. Automobiles of these vintages include extensive
electronics and represent a significant fraction of automobiles on the road today. The
testing was conducted by exposing running and nonrunning automobiles to sequentially
increasing EMP field intensities. If anomalous response (either temporary or permanent)
was observed, the testing of that particular automobile was stopped. If no anomalous
response was observed, the testing was continued up to the field intensity limits of the
simulation capability (approximately 50 kV/m).
Automobiles were subjected to EMP environments under both engine turned off and
engine turned on conditions. No effects were subsequently observed in those automobiles
that were not turned on during EMP exposure. The most serious effect observed on running
automobiles was that the motors in three cars stopped at field strengths of approximately
30 kV/m or above. In an actual EMP exposure, these vehicles would glide to a
stop and require the driver to restart them. Electronics in the dashboard of one automobile
were damaged and required repair. Other effects were relatively minor. Twenty-five
automobiles exhibited malfunctions that could be considered only a nuisance (e.g.,
blinking dashboard lights) and did not require driver intervention to correct. Eight of the
37 cars tested did not exhibit any anomalous response.
Based on these test results, we expect few automobile effects at EMP field levels below
25 kV/m. Approximately 10 percent or more of the automobiles exposed to higher field
levels may experience serious EMP effects, including engine stall, that require driver
intervention to correct. We further expect that at least two out of three automobiles on the
road will manifest some nuisance response at these higher field levels. The serious malfunctions
could trigger car crashes on U.S. highways; the nuisance malfunctions could
exacerbate this condition. The ultimate result of automobile EMP exposure could be triggered
crashes that damage many more vehicles than are damaged by the EMP, the consequent
loss of life, and multiple injuries.
