The MTA will make its pilot program of testing train operators on the Metro-North for sleep apnea permanent and will also expand the program to the city subway system, buses, and the Long Island Rail Road, officials said on Tuesday.

The agency started the program last year after an engineer nodded off at the controls while driving through the Bronx, derailing the train and killing four people.

Metro-North’s 438 engineers have been tested for a year, and the agency expects to test at least a thousand more drivers and conductors throughout New York City Transit and the LIRR, said spokesman Aaron Donovan

The program is needed to make sure that employees in charge of moving vehicles have gotten enough quality sleep so that they don’t sack out on the job.

“These are procedures we are putting in place to improve the overnight sleep and make sure they are completely fit for duty and able to operate trains,” said Donovan.

The agency released on Tuesday a request for proposals for a company to handle the testing, which consists of a questionnaire, a sleep study, and followup treatment for those who are found to have the condition.