The federal mandate requiring automatic emergency braking on heavy trucks has moved again. NHTSA and the Federal Motor Carrier Safety Administration proposed a rule covering all new Class 7 and Class 8 trucks; it was originally expected to be finalised in early 2025, and is now scheduled for reissue as a supplemental proposed rule in early 2026, allowing further analysis and public comment before adoption.
What the rule would require
The proposal mandates factory-installed automatic emergency braking (AEB) and electronic stability control (ESC) on new Class 7 and Class 8 trucks starting in 2027, with medium-duty vehicle requirements expected to follow in 2028.
An AEB system uses multiple sensor technologies to detect an imminent crash and applies the brakes automatically if the driver has not done so — or adds braking force to supplement the driver’s input. The proposed standard covers speeds from roughly 6 mph up to about 50 mph.
That speed range matters. Low-speed capability addresses parking-area and congestion incidents; the upper range covers the highway rear-end collisions that produce the most severe outcomes.
The projected benefit
NHTSA estimates the proposed rule would prevent 19,118 crashes, save 155 lives and prevent 8,814 injuries annually.
Those are agency projections attached to a proposal, not measured outcomes. They are the figures that will be scrutinised in the comment period, and they are worth reading as an estimate rather than a result.
What the delay means for fleets
The direction is settled; the date is not. A supplemental proposal is not a withdrawal. Planning on the assumption that AEB will be required on new heavy vehicles is reasonable; planning on a specific compliance date is not.
Procurement cycles are the real constraint. Class 8 trucks are typically ordered well in advance and kept for years. Fleets ordering now for 2027 delivery are already inside the window, whether or not the rule is final.
Many manufacturers already fit AEB. The systems are widely available as standard or optional equipment. The regulation would set a floor and standardise performance, not introduce the technology.
Comment periods are the leverage point. A supplemental proposal reopens the record. Fleets with operational data on false activations, maintenance burden or sensor performance in poor weather have a genuine opportunity to influence the final text.
The practical read
For safety managers, the useful position is to treat AEB as an operational question rather than a compliance one. If the technology prevents a fraction of the crashes projected, the business case does not depend on the rule being finalised.
The regulatory timeline has slipped twice. The crash statistics it is responding to have not.
