WASHINGTON, Sept 29 (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.