The U.S. National Highway Traffic Safety Administration (NHTSA) announced on Friday that it is seeking additional information in its investigation into Amazon.com’s self-driving Zoox vehicles due to unexpected braking incidents that led to two rear-end collisions.
The agency, which opened the probe into the crashes earlier this month, has requested video footage of the collisions and documents from Zoox related to the vehicles.
NHTSA expressed concern that “vehicles exhibiting unexpected rapid braking may increase the risk of crash,” and added that the “risk is particularly acute to road users behind the Zoox vehicles who are unable to reasonably anticipate or react to the unexpected sudden braking.”
Earlier this month, NHTSA announced it had opened a preliminary investigation into 500 Zoox vehicles with automated driving systems after two crashes involving Zoox’s self-driving technology resulted in minor injuries to motorcyclists.
Each incident involved a Toyota Highlander equipped with the automated driving system, which is being tested in real-world conditions using those vehicles.
A Zoox spokesperson did not immediately comment on Friday but had previously stated that “transparency and collaboration with regulators is of the utmost importance, and we remain committed to working closely with NHTSA to answer their questions.”
In March, Zoox announced it was expanding its vehicle testing in California and Nevada to include a wider area, higher speeds, and nighttime driving, as it competes with Alphabet’s Waymo robotaxis. Amazon acquired Zoox in 2020 for $1.3 billion.
NHTSA stated that both crashes occurred during daytime hours and within the Zoox system’s operational design limits.
The investigation will evaluate the automated driving system’s performance, particularly related to the collisions, as well as “the behavior in crosswalks around vulnerable road users, and in other similar rear-end collision scenarios.”
In March 2023, NHTSA opened a probe into Zoox’s self-certification in 2022 of a robotaxi without traditional driving controls, which is a standard industry practice subject to regulatory oversight.
NHTSA has initiated a series of investigations into the performance of self-driving vehicles, including those operated by General Motors’ Cruise and Alphabet’s Waymo.
The agency is also investigating Tesla’s December recall of more than 2 million vehicles to install new Autopilot software after receiving reports of 20 crashes involving vehicles with the software update. Autopilot is an advanced driver assistance system that does not make vehicles fully self-driving but handles driving tasks like steering and braking.