No photos, but Google did turn up a number of resources:

• U.S. Department of Transportation. "...such regulations as may be necessary to mitigate the impact of the discharge of human waste from railroad passenger cars on areas that may be consideed environmentally sensitive." (The link is a scan of a page, but fortunately as it is in PDF form the text can still be extracted.)
• "The Rock Island mainline thru south Wichita ran down the center of Mead street for several blocks in the mid Fifties (and still does) with light industry, wharehouseing and residential homes paralleing the tracks...The passenger trains; well first thing that comes to mind, unfortunately, was the dumping of human waste inside the city limits. They were'nt supposed to, but it happened occasionally."
• WDBJ 7 news at 11 for 11/21/97. It's time to put 21st-century toilets on the trains. That's the announcement from Norfolk Southern today. The railroad says it will replace the dry hopper system on its locomotives. Using dry hoppers, railroad employees relieve themselves in plastic bags. But unions have complained the system is not sanitary. And farmers have found bags of human waste on their property near railroad tracks. One Bedford County farmer is suing the railroad. He says the waste has hurt his cattle and damaged his equipment. "...AND THIS STUFF HERE IS LIKE COMING OUT OF A SEPTIC TANK. WHEN YOU HIT IT WITH LIKE A GALLON OF THE STUFF, IT'S LIKE A SPRAY WHEN THE HAY BAILER HITS IT. Chattin says he's been finding bags on his farm for the last 13-years.
• Las Vegas. "The Clark County Health District survey found areas along the sidewalk and railroad tracks were used for human defecation. Human waste was found continuously along a quarter-mile stretch of a block wall. Offensive odors of urine and feces were present at the time of inspection."
• Cape Cod Railroad. The lawsuit charges that the Cape Cod Railroad dumped sewage onto tracks which run through ecologically sensitive areas and near homes and wells.
  

Seems to be a problem--at least in the US--but fortunately we did not notice it happening while visiting China. (Though it seems quite possible, as a number of important health-related issues that are closely monitored in the US are rather relaxed in Asia.)



Perhaps Norman Mineta at the U.S. Department of Transportation (Placemark attached) would know the latest status on track-side dumping of human waste.