it’s the “train” which runs
about 10 minutes ahead of the Hiram Bigham train [which checks for rockfalls and
land slides and/or any other “stuff” which may have found its way onto the tracks.
If something is spotted the big train is contacted {by radio signals} and therefore has
plenty of time to slow down or stop while the problems are rectified], on the journey
between Cusco and Machu Picchu. It could have been a VW Combi van at some stage.