Mr Brown’s previous role covered London Overground, DLR, Trams and TfL Corporate.
He was also the chair of the Independent Railway Assurance Board for Crossrail and the independent safety expert on the Olympic Delivery Authority Games Transport Safety and Security Committee.
Before this he was executive director for health, safety, quality and environment at Tube Lines between 2002 and 2005 as well as holding other senior roles in the sector.
Crossrail programme director Simon Wright said: “The Crossrail programme is approaching 75 per cent complete with major fit-out of the tunnels and stations underway.
“Martin’s considerable expertise in rail health and safety will be invaluable as we progress towards the start of dynamic testing in November 2017.”