The works will include an early warning system that will alert the Public Transport Authority to potential dangers from ships after several vessel hits to the rail bridge in recent years.
Transport Minister Dean Nalder said the work was needed to avoid a catastrophe should another vessel hit the bridge.
�This early warning system will provide an extra level of safety by alerting the Public Transport Authority, giving it the ability to switch the signals to red and stopping trains from crossing the bridge,� he said.
Works will also include the installation of concrete buffers downstream to absorb impacts, as well as the strengthening of the Fremantle traffic bridge through repairing 57 piles and reinforcing timber fenders with metal.
Mr Nalder said work would be completed around September next year, with occasional closures of the traffic bridge to allow for work to be done.