Environmental Control for a Rapid Transit System in a Tropical Climate

The need for rapid transit systems in tropical cities has brought into focus the problem of giving acceptable conditions underground when the ambient temperature is elevated and coupled with high levels of humidity. It is an economic problem to set reasonable comfort levels. The amount of power liberated within a tropical underground system is discussed and the size of air conditioning plant required for trains if these are used. Three general systems of dealing with the overall problem are discussed, together with the effect on the systems arising from the speed of the trains and the special problems created when stationary within the tunnels. The conclusions indicate that for tropical conditions a closed system underground is to be preferred without air conditioning on the trains. The use of power to achieve acceptable conditions is one of economics rather than a technical question, but cooling is expensive in energy for any underground system in the tropics.