NHTSA Orders Rollover Prevention Technology
A new rule proposed by the National Highway Traffic Safety Administration would require passenger vehicles to include rollover prevention technology.
On September 18, NHTSA published a notice of proposed rulemaking to require that all passenger vehicles under 10,000 pounds be required to be equipped with electronic stability control (ESC). ESC is an expansion of antilock brake technology which combines independent braking with vertical rotation (yaw) sensors to help prevent loss-of-control accidents, and particularly rollover.
Preliminary studies show promising statistics on ESC’s ability to reduce the likelihood that a driver will lose control of a vehicle, and that it also mitigates the severity of single-vehicle accidents, reducing the number of fatalities due to such accidents.
ESC will primarily prevent single-vehicle accidents that result in loss of control of the vehicle. Studies by NHTSA and the Insurance Institute for Highway Safety have shown that ESC has a strongly positive effect in preventing single vehicle accidents, particularly rollover in SUVs.
ESC works by correcting for disparity between the intended line of travel and the trajectory that a vehicle is actually taking. All ESC systems incorporate antilock brakes along with sensors to monitor steering input and intended line of travel. When the ESC system senses that a driver is about to lose control, the independent brakes engage to correct for rotation about the vertical axis.
A study done by NHTSA shows that ESC reduces single vehicle crashes in passenger cars by 34% and 59% for SUVs. The rollover prevention statistics are even more encouraging – 71% for passenger cars and 84% for SUVs. Preventing rollover accidents is the first line of defense in preventing deaths due to rollover, of which there are more than 10,000 per year.
NHTSA has proposed a phase-in of ESC, mandating that:
NHTSA suspects that, because many manufacturers are already including ESC as standard equipment on SUVs, that manufacturers may comply with the rule prior to the mandated date.
While it is important that vehicles be equipped with ESC to help prevent rollovers from happening, there is still much to be done about protecting passengers when vehicles do roll over. NHTSA’s proposed rule for roof crush did little to protect passengers – 70% of vehicles already meet the proposed standard. Also, seat belt failure presents a significantly higher risk of ejection in a rollover crash. NHTSA reports that in 52% of rollover crashes, passengers were partially or completely ejected. A 2003 NHTSA study showed that 50% of partially ejected occupants were wearing seat belts. Addressing protecting passengers in the event of a rollover crash is also important; therefore, while ESC is an important addition to promote vehicle safety, there is still much to do to promote safety in the event of a crash.
For more information on how ESC works and its safety benefits see the Insurance Institute for Highway Safety report:
For more information on seat belt failure see Public Citizen’s report, Rolling Over on Safety: The Hidden Failure of Belts in Rollover Crashes
To read Public Citizen’s response to NHTSA’s rules on roof crush prevention standards: