Building a railroad grade through Wisconsin's hill country was a monumental task. To create a nearly level grade of 3 percent, workers dug three tunnels, shaved down ridges, and filled in low areas like this one. Black cinders, by-products of coal-burning engines, were used to create the tall, narrow embankment or fill here. This was the only fill on this rail line composed almost entirely of cinders. It was built after the rail line opened and replaced a bridge that once stood here.