WASHINGTON (Reuters) -Two U.S. senators urged the automobile safety regulator on Monday to investigate reported failures of Tesla's Full Self-Driving system to detect and safely respond to railroad crossings, citing risks of "catastrophic" collisions.

On its website Tesla says the system allows a vehicle to drive occupants "almost anywhere," handling everything from route navigation to lane changes, steering and parking, although it still requires supervision by a human driver.

Democratic Senators Ed Markey and Richard Blumenthal cited a growing number of reported near-collisions in their call for an investigation by the National Highway Traffic Safety Administration.

"A miscalculation at a train crossing can lead to catastrophic, multi-fatality collisions involving vehicle occupants, train passengers, and rail workers," the senators wrote in a letter released to the public.

The impact of such errors would far outweigh dangerous mistakes like a missed traffic sign or an illegal lane change, they added.

Tesla did not respond to a request for comment.

In a statement, the regulator said it had received the letter and was gathering information on such incidents.

It added that while the Tesla system provided support to the driver in steering, braking, and acceleration controls in certain situations, it required the driver to keep operational control at all times.

Tesla's Full Self-Driving system, which is more advanced than its Autopilot system, has already been under investigation by NHTSA.

In October 2024, the agency began an inquiry into 2.4 million Tesla vehicles equipped with FSD after four reported collisions in conditions of reduced roadway visibility, such as sun glare, fog or airborne dust, including a 2023 fatal crash.

The senators urged NHTSA to consider curbs on Tesla's use of the system.

"The agency should consider clear and obvious actions to protect the public, including restricting Tesla's FSD to the road and weather conditions it was designed to operate in," they said.

Telsa's other automated vehicle features have also drawn agency scrutiny.

In January it began an investigation into 2.6 million Tesla vehicles over reports of crashes involving a feature that lets users move their cars remotely.

NHTSA is also reviweing Tesla's deployment of self-driving robotaxis in Austin, Texas, launched in June, telling the company in a July 1 email it wanted to know if Tesla employees could remotely drive the vehicles.