Concepts studies for future intracity air transportation systems

Abstract

Summary: This report is concerned with describing the possible application of future air transportation systems within urban areas of the United States. The planning horizon extends to 1995 and the report focuses on the period 1980-85 for introduction of urban air systems. The general conclusion of the study is that urban air systems will be technically and operationally feasible, but that economic viability remains inextricably linked to future governmental policies on urban development, and consequently policies for development of urban transportation. In view of the uncertainties in these policies, it becomes difficult to be definitive about the forms of future urban air systems and the research and development needs to develop these systems. The marketing section of the report identifies the kinds of urban travel markets, and attempts to apply a modal split model to show the share of the travel market which an air system would capture in competition with automobile or new forms of rapid transit. The results indicated the need for a high frequency of air service, and low values of access and egress times and costs, and reasonably competitive fares. The air system did not gain any appreciable share of the travel until trip distances were over 20 miles. Since most of the trips in an urban area are under this distance, the overall penetration of the urban travel market was less than one per cent. Application of the modal split model to data for a 1980 case study of the Boston area indicated that the loads were much too low to justify a large scale urban system. Although the modal split model results can be questioned and more work on such models is indicated, the general nature of these marketing conclusions is unlikely to change. There were two concepts for urban air systems described in this study: a "metrobus" concept which used 40-80 passenger vehicles as a public carrier in the urban area and a "metrotaxi" concept which used 4-5 passenger VTOL air taxis as a private-for-hire carrier. The components of these systems (vehicles, metroports, air traffic control system) were described as they might exist for the 1980-85 period. Appendix B describes an analysis for any public urban transportation system which demonstrates that a large number of stopping points are required of a large scale urban system in order to reduce the access and egress times and therefore the total trip time. Its conclusion is that a public urban system can never compete with a private system like the automobile for the total mass market, but must attract a much reduced travel volume consisting of trips between local areas surrounding its stopping points. This result led to access plus egress times for the air urban system on the order of 30 minutes by automobile or taxi which greatly reduced its speed advantage particularly for the shorter trips. The dominant problem in implementing an urban air system is community acceptance of the metroport, and the prime factor would be the noise of the air vehicles. A peak noise level of 85 EPndb at 500 feet is suggested as acceptable based on experience with 70 heliports in the Boston area. However, there is a need for establishing a community noise criteria based on factors other than peak noise such as frequency of service, background noise levels, number of listeners, etc. and using it to establish noise categories for metroport operation. This would give the community some assurance that the volume of noise pollution from the site can be controlled. Planning for a future urban air system is linked to planning for both future airport development and future intercity V /STOL systems. Land side congestion problems at major airports can be relieved through the provision of remote check in facilities which have an air link to the airport. The construction of new airports at sites somewhat removed from urban areas may become reasonable if urban air service exists. Similar factors affect the problems of passengers transferring from airports to metroports for intercity V/STOL service. The metroports are a ground facility common to the metrobus concept for urban air systems and intercity V/STOL, and as such link the development of these two systems.