Truck safety regulators are about to post a new, long-awaited rule aimed at shoring up driver medical standards.

The rule will require those who perform medical exams for drivers to be trained, tested and certified to a national standard. It also will create a national online registry of examiners who have met the certification requirement.

Drivers have long been required to pass a medical exam that includes the heart, lungs, muscular functioning, vision and hearing, among other things. They have to pass the exam at least every two years to keep their medical certificate.

But, strange as it may seem, the Federal Motor Carrier Safety Administration does not really have a handle on who is doing the exams.

Examiners come from a variety of medical specialties. They can be doctors, osteopaths, chiropractors, physician assistants or advance practice nurses, for example. But the agency does not know who is doing the exams, how many examiners there are, where they are located or what skills and training they have.

Regulators have been working on this problem since 2005, when the agency began public discussions on how to put a registry together. The proposed rule came out in 2008.

"This new rule will ensure that healthcare professionals conducting exams keep in mind all of the demands required to operate large trucks and passenger buses safely," said Transportation Secretary Ray LaHood in a statement.

FMCSA Administrator Anne Ferro added that truck and bus drivers deserve to have well-trained examiners. "By holding medical examiners accountable to high standards of practice, we raise the bar for safety and save lives through increased commercial driver and vehicle safety," she said in a statement.

The rule, scheduled for Friday's Federal Register, will unfold in stages.

On May 21 the National Registry will be available at an FMCSA website, and training and testing standards for medical examiners will be posted. The site will be open to medical examiners, drivers, employers, enforcement officials and the public.

Organizations that provide training for examiners will have to develop curricula that meet the agency's guidelines, and will have to get themselves listed on the registry. Starting August 20, examiners take the certification test at an FMCSA-approved test center, and drivers and carriers can search for approved examiners on the registry.

In two years, by May 21, 2014, medical examiners have to be certified and registered, and drivers must be using a certified examiner. The agency said that examiners who don't meet standards will be taken off the registry.

American Trucking Associations welcomes the rule, said spokesman Sean McNally.

"We believe that educating medical examiners about the physical requirements to drive a commercial motor vehicle and testing their knowledge of FMCSA's medical requirements will ensure only medically qualified drivers operate CMVs," he said in a statement.

The association is concerned that examination costs might go up in areas of the country where there are fewer medical providers, he noted.

But the new system also will help prevent fraud and it sets the stage for the next big improvement, in which medical examiners will put driver information directly into the driver's motor vehicle record, he said.