DOT Helmet Standard FMVSS 218, Page 4.
Test to be performed at 13.4 MPH.
DOT Helmet Standard FMVSS 218, Page 1.
Peak g force measured not to exceed 400g
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This video, made by the testing agency in the UK, animates helmet testing. For reference, regulation speed referred to in this video is 7.5 meters/second which is 18.0 miles/hour. This is a higher speed than the 6.0 meters/second (13.4 miles/hour) required in the USA regulation contained in the Federal Motor Vehicle Safety Standard (FMVSS) 218, paragraph S7.1.4. Neither speed is considered “high speed” for motorcycle drivers.
Short video of test: While watching the test, try to imagine a test dummy connected to the helmet and consider the other injuries that would occur in addition to any injury to the brain, as measured by the sensor.
This video shows helmet testing, and compares DOT, ECE, and Australia testing at Nolan in Italy.
This video demonstrates the “masking” effect helmets may have on collision victims. First, when the breakable stick is used to strike the young man, he is deafened. Then, consider, that if he didn’t have a helmet on, he would not have let any more strikes hit his head after the first “breakable stick” blow. Notice that on the first blow with the crowbar, the young man’s brain is damaged and the young man is knocked out. After he becomes conscious, he is unaware of the seriousness of his injury. Due possibly to empathy, the other young men plead with him not to continue, and the man delivering the blows has difficulty striking the helmeted young main again. This video demonstrates one can injure the brain, and masks the injury to the victim, by preventing injury the skin and skull.
Helmets reduce head injury in fatal crashes. In this test-dummy example, the collision would likely be fatal. The helmet would reduce, and mostly prevent any skull or scalp injuries. Pay special attention to the base of the head and neck. The the sum of the injuries received throughout a persons body in this type of collision can result in a fatality. The co-morbidities would combine in stress on the body and likely result in fatality.
This video shows an example of a low momentum and high energy collision. The combined momentum of the SUV and Truck is small whereas the energy of this combination is not small. Collisions in systems that have low momentum and high energy result in high morbidity. Warning: Many of us underestimate the violence of a low momentum-high energy collision.
Some more Physics care of Myth Busters. Note that the damage is done by the Kinetic Energy (KE). KE = 1/2 Speed Squared. Note that the 50 MPH cars experienced 58 Gs of deceleration (or less). 58 Gs of force is a deadly amount of force.
For reference, compare this to acceptable Gs for the brain in an approved helmet: From FMVSS218 Section 5.1 – “Impact Attenuation. When an impact attenuation test is conducted in accordance with Section 7.1, all of the following requirements shall be met:
(a) Peak accelerations shall not exceed 400g;
(b) Accelerations in excess of 200g shall not exceed a cumulative duration of 2.0 milliseconds; and
(c) Accelerations in excess of 150g shall not exceed a cumulative duration of 4.0 milliseconds.”