Infrastructure is set to become a key battleground in the next federal election with Opposition Leader Bill Shorten on Monday committing $2.24 billion to Brisbane's $5.4 billion Cross River Rail – a project that has been consistently rebuffed by Prime Minister Malcolm Turnbull.

It follows multibillion dollar commitments by Mr Turnbull to road and rail projects in recent weeks, including $1 billion for the M1 freeway expansion on the Gold Coast and $5 billion for a rail link to Melbourne airport in Victoria.