This is the Bristol and Bath Railway Path grade crossing at the southern end of Bitton Station platform. Both the path and the railway cross above the A431 road which lies immediately behind the gates at this point. The crossing guard utilizes the small shanty labelled "South Ground Frame". This is the gate that was struck and damaged by two run-away carriages on 25 Jul 2018. Here's the news article and also the investigation findings by the government's Rail Accident Investigations Branch (RAIB) Independent Report.