Perth's urban transport DEC is projected to grow from $9.13 billion in 2011 to $33.62 billion in 2031 - an increase of 6.7 per cent per year. The cost of delay on greater Perth's road network in 2011 was around $2 billion. In the absence of any additional capacity (other than projects already under construction or funded), and based on the high levels of population growth projected in the Audit, the cost of delay is projected to grow to around $16 billion in 2031.