An empirical method is developed for evaluating air flow rates which result from piston action subway trains moving in a single-track tunnel. It is assumed that air behaves as a perfect gas and that air flow is one dimensional, isothermal, unsteady, viscous, and compressible. An initial step in the proposed method is to divide the subway system into a series of finite segments; these include eleven sections of single-track subway running through a tunnel between two subsurface stations. Application of the principle of conservation of mechanical energy to these finite segments results in a set of simultaneous, non-linear, ordinary differential equations which reflect the interdependence of pressure, density, and velocity. The method uses a six step interactive process: (1) assume initial density distribution; (2) solve simultaneous equations for velocity distribution; (3) calculate pressure distribution; (4) compute density distribution; (5) compare computed and original density distribution; (6) if the densities do not match within specified tolerances, reiterate using the computed density distribution. All relevant data and equations are contained and a numerical example assuming incompressible flow is appended.

  • Corporate Authors:

    Parsons, Brinckerhoff, Quade and Douglas, Incorporated

    111 John Street
    New York, NY  United States  10038
  • Publication Date: 1970-10

Subject/Index Terms

Filing Info

  • Accession Number: 00044194
  • Record Type: Publication
  • Source Agency: Urban Mass Transportation Administration
  • Files: TRIS, USDOT
  • Created Date: Jun 15 1974 12:00AM