Transportation and air quality planning have been closely linked through legislation and regulations, which seek to reduce mobile source emissions. Where transportation and air quality planning were formerly conducted in isolation, practitioners now see the mutual benefits of sharing databases, using consistent assumptions, and coordinating implementation strategies to ensure that both transportation and air quality planning goals are achieved. Partnerships have developed, and in many areas have become institutionalized. Where these partnerships rely on interagency coordination strategies, employ strong technical approaches and forecasting techniques, and include agreement on how to meet common goals, they offer the greatest promise for clean air and mobility.
Decisions made in the air quality planning process and during SIP development can have a direct effect on transportation programs and projects. Transportation agencies should participate fully in the air quality planning process to ensure that decisions made reflect community priorities, including mobility.