Monkeying around on an escalator

It has been reported that more than a million people descend on Batu Caves in Malaysia at this time of year to celebrate the Indian festival of Thaipusam. Recently, it has been proposed to build an escalator alongside the 272 steps to help devotees reach the temple at the top. While this sounds like a good idea, many will know that Batu Caves is also famous for something else - the monkeys! Which got me thinking - how would you stop the monkeys from damaging the escalator or causing havoc otherwise? I had a quick look on the patent databases for existing solutions but drew a blank. Perhaps there is an opportunity here for an inventor to solve the problem…