With rising peak oil concerns, climate warming exacerbated by carbon emissions and high energy prices, the conventional automobile industry is becoming less and less feasible to the conversation of sustainability. Revisions of urban transport systems that foster mobility, low-cost transportation and healthier urban environments are needed. Such urban transport systems should consist of a combination of rail transport, bus transport, bicycle pathways and pedestrian walkways. Public transport systems such as underground rail systems and bus transit systems shift huge numbers of people away from reliance on car mobilization and dramatically reduce the rate of carbon emissions caused by automobile transport. Carpooling is another alternative for reducing oil consumption and carbon emissions by transit.