The term 'Mountain Road Feature' can be broken down into three crossword solutions: ESS (3 letters), SHARPTURN (9 letters). ESS stands for Escape Slope System, which is a safety feature used on mountain roads. It is designed to help drivers avoid accidents by providing them with an escape route in the event of a sudden stop or skid. SHARPTURN stands for Sharp Turn Warning System, which is another safety feature used on mountain roads. This system warns drivers of sharp turns ahead and helps them adjust their speed accordingly. Both of these features are designed to make mountain roads safer for drivers.