Train surfing on The Sydney Harbour Bridge is not a new phenomenon. A search through the State Records NSW has unearthed one of the first documented occurrences.  This photo from March 11th 1932 captures the moment during load testing, shortly before the official opening on the March 19th by Francis de Groot.

We find this to be a fitting photo capturing both Dr John Bradfield, who oversaw the design and building of the Sydney Harbour Bridge and Mr Lawrence Ennis who supervised the construction.