The next stage was the release of two white papers in May 2008. "Paper 1 - Visions, Goals, and Objectives", presented the basis for the final RTP, with specific goals and objectives that could be used for its development and evaluation. A broader proposed vision for the entire system was also presented. "Paper 2 - Preliminary Directions and Concepts", looked at various policies, programs and tools that could be utilized in the RTP. There were also various transportation system concepts that were modelled and evaluated based on resulting transit ridership, urban congestion, and the emission of greenhouse gas and other air pollutants.