CH-77-01-2 -- The Use of Underplatform Ventilation Systems in the Control of Subway Thermal Environment

Underplatform exhaust systems take advantage of the. fact that the major source of subway heat is the train, and that the release of this heat to the subway air occurs for the most part beneath the train through convection from the propulsion - braking system, air-conditioning condensers and auxiliaries. In concept, the underplatform exhaust system sweeps this heated air from beneath the train while it is in the station and expells the heated air from the subway. Even though this heat removal occurs only during a portion of the train operating cycle, the potential for reducing the subway. heat load is substantial. Various underplatform ventilation system concepts have been incorporated in the environmental control designs of future subway systems throughout the country.

A field test program sponsored by the Transit Development Corporation and with the cooperation of the Toronto Transit Commission developed basic performance data for a full platform length underplatform exhaust system. The results of these tests provide the engineer with useful information regarding the design, operation and effectiveness of underplatform ventilation systems.