How about a 70.9% grade on a hillside railroad?
The Johnstown Inclined Plane has been the world's steepest vertical railroad since 1891. It is still operating as a National Historic Landmark in Johnstown, Pennsylvania. It was built after the devastating Johnstown Flood of 1889 (2,209 victims) as a future escape route from flooding that was very beneficial in the 1936 Johnstown Flood, and was still used during the 1977 Johnstown Flood.
Main Page is http://www.inclinedplane.com/
Links Page is http://www.inclinedplane.com/othrvrr.htm
Here's some text from the Links Page...
Funiculars, Inclined Planes and Vertical Railroads are all similar devises that pull a vehicle up a steep incline, utilizing a cable (steel rope) system. A variety of such vehicle systems exist around the world, from the simple one and two passenger variety, often used by homeowners who live atop cliffs or mountaintops, to those the size of Johnstown's Incline, with cars that can accommodate vehicles as well as passengers. Some funiculars consist of many cars strung together, not unlike a true railroad.
Some, like Johnstown's Incline, use two cars to counterbalance each other on two separate tracks. Others consist of two cars, on one track with a central siding where the cars separate and bypass one another, such as the Altoona Curve funicular. Other types of funiculars may utilize only one passenger car that is hoisted up and down the hillside or mountain.
I drive by this unique railroad almost every day, and have often thought about modeling it if the design and space allows it. A steep prototype would mean less layout real estate, and it would not necessarily have to be connected to any other part of the layout with an interchange. The Johnstown prototype offers hillside trees, observation platforms, hilltop restaurant, unique passenger cars, and an approach truss bridge spanning a river.
As Mister Rogers Neighborhood might say, "Can you say 99 44/100% scratchbuilt?"
Horseshoe Curve's Funicular (really a hillside elevator) http://www.railroadcity.com/hc/index.php seems "almost toylike" when compared to the Johnstown Inclined Plane, or the Duquesne Incline http://incline.pghfree.net/ in Pittsburgh, Pennsylvania.
I do remember seeing a European funicular model manufacturer somewhere in website travels, but it was more of a "passenger car-pulling" model that reminded one of a cog-style railroad without the Johnstown or Pittsburgh counter-balancing cars and was closer to what is found at Pike's Peak http://www.cograilway.com/