Since the present alignment of MD 135 was completed west of Bloomington in the late 1950s, the descent of Backbone Mountain has become notorious due to its steep grade and the 90 degree turn at the bottom to avoid a mountain dead ahead. A retaining wall at the bottom of the mountain features white crosses in memoriam of those who lost their lives; there were 24 crosses painted as of 2009. After five people had been killed on the descent by 1965, the State Roads Commission responded in 1967 by enacting the truck speed limit of , marking the three mandatory stopping areas, and installing ample warning signage, including the infamous If Brakes Fail Ditch Truck Immediately sign. In 1997, signs were installed on Interstate 68, US 219, and US 40 advising truckers to use MD 36 instead of MD 135 to access Luke and Westernport. The runaway truck ramp was installed by 2005 and supplemented with a runaway truck warning system and updated signage in 2007.