Of the control strategies States may choose to implement, some may be on-road mobile source measures to reduce vehicle use or change traffic flow or congestion conditions. These measures are known as transportation control measures (TCMs). A TCM is any measure that is specifically identified in the SIP for the purpose of reducing emissions or concentrations of air pollutants from transportation sources.
Transportation agencies have the most thorough knowledge of the feasibility of many of the different types of transportation programs and projects that can be implemented in their area. Transportation control measures should be developed through both the transportation and air quality planning processes to insure future implementation. Transportation agencies will be held accountable for the implementation of TCMs from SIPs in the development of future transportation plans.
The SIP must provide for the implementation and enforcement of TCMs. TCMs should be developed jointly by transportation and air agencies as part of the transportation planning process, and incorporated into the SIP. In addition, many transportation plans and TIPs include TCM-like projects such as transit investments or HOV lanes, which are not included in the SIP. These measures can help improve air quality but are not considered legally enforceable commitments unless they are identified as TCMs in the SIP.
TCMS that are identified in the CAA include:
Programs for improved public transit
Restriction of certain roads or lanes to, or construction of such roads or lanes for use by, passenger buses or high-occupancy vehicles
Employer-based transportation management plans, including incentives
Traffic flow improvement programs that achieve emission reductions
Fringe and transportation corridor parking facilities serving multiple-occupancy vehicle programs or transit service
Programs to limit or restrict vehicle use in downtown areas or other areas of emission concentration particularly during periods of peak use
Programs for the provision of all forms of high-occupancy, shared-ride services
Programs to limit portions of road surfaces or certain sections of the metropolitan area to the use of non-motorized vehicles or pedestrian use, both as to time and place
Programs for secure bicycle storage facilities and other facilities, including bicycle lanes, for the convenience and protection of bicyclists, in both public and private areas
Programs to control extended idling of vehicles
Reducing emissions from extreme cold-start conditions
Employer-sponsored programs to permit flexible work schedules
Programs and ordinances to facilitate non-automobile travel, provision and utilization of mass transit, and to generally reduce the need for single-occupancy travel, as part of transportation planning and development efforts of a locality, including programs and ordinances applicable to new shopping centers, special events, and other centers of vehicle activity
Programs for new construction and major reconstruction of paths, tracks or areas solely for the use by pedestrian or other non-motorized means of transportation when economically feasible and in the public interest
Programs to encourage removal of pre-1980 vehicles