A national tour of doctors advocating a single-payer healthcare system stopped in Louisville Tuesday.The Mad as Hell Doctors brought their calls for a healthcare system similar to an expanded version of Medicare or the Canadian healthcare system to Gray Street downtown. That's where they met Dr. Garret Adams of the Physicians for a National Health Program of Kentucky.Adams is a pediatrician and former professor, but not one of the Mad as Hell Doctors. He says a single-payer system is the most beneficial arrangement for doctors."It frees them up from the hassles of the insurance companies," he says. "Doctors are driven crazy by the demands of the insurance companies. They can't provide for their patients what they want to provide for their patients and all of the hassles are taking up their time and their money."The tour started in the Northwest and will continue heading east. It will end in Washington DC on the 30th.