It doesn’t say 110°, but 110% grade. Percent grade is defined as the amount of feet in elevation versus the number of feet traveled forward; hence a 110% grade means a change in elevation of 110 feet for every 100 feet traveled horizontally. It’s a little less than 48° angle, maximum, or (in British gradient measurments) 1 in 1.1.
Correction: The British grade measurement would be 1 in 0.91. Sorry about that.