By most measures, including costs of construction, maintenance, operation, energy consumption, ridership, serviceability and longevity of equipment, subways are among the least efficient transportation systems operating in the United States. While quality of service and safety are superior, subway access is limited to relatively small numbers of riders by infrequent stations and restricted service areas. Access to stations is further restricted by a lack of interface or interconnection with other transportation modes, including auto, bus, pedestrian, rail and other mass transportation systems.
Urban areas and populations with access to subways are provided with high quality and reliable service. Presenting users with attractive transportation alternatives, subway systems can, under certain circumstances and conditions, generate measurable reductions in traffic congestion in their localized service areas. However, significant traffic congestion relief has only been demonstrated by extensive subway systems located in dense urban and suburban settings.
By nearly every economic measure; whether cost per passenger boarding, per mile of construction or hour of operation, purchase and replacement of rolling stock, equipment repair or cost per new passenger seat, subway construction, infrastructure and equipment are consistently the most expensive of mass transportation systems. Furthermore, the capital costs of construction, coupled with consistently deficient fare income relative to operating expenses, require substantial long-term financing and debt service, potentially extending beyond the operational life of the subway trains and equipment.