Indeed, the primary reason a government would do a P3 is to achieve better value for taxpayers, and by that, the particular jurisdiction would mandate the private sector delivery agent to meet certain performance levels. In the case of a road, that would mean a certain service standard for patching potholes or doing regular maintenance to avoid potholes from materializing. The government basically commits to long-term maintenance of those assets via service payments to the P3 delivery agent in the case that it's not funded by user fees. If it's funded by user fees, again the P3 agent has to reach certain service standards so it can collect the funding.
On May 17th, 2012. See this statement in context.