16 TR News, November–December 1987

RESEARCH PAYS OFF

Urban MassTransportationAdministration

Ventilation andEnvironmentalControl in Subways

Urban public transportation, afteryears of neglect, became the focus ofattention in the mid 1960s. As a result,many large metropolitan areas began toplan new or expanded rail transit sub-way systems. At the same time, engi-neers, responding to higher public ex-pectations and environmental consid-erations, began to take a closer look atthe adequacy of the 40-year-old designmethods, because no major subwayconstruction had been undertaken in theUnited States since the 1930s.

Problem

During initial planning for new subwaysystems, it soon became apparent thatone of the most critical and vital consid-erations in transit tunnel design was theneed for a well-founded environmentalcontrol system. This system would in-clude temperature and humidity control,circulation of fresh air (to meet bothnormal and emergency requirements),and safety features in case of fire. Be-cause design and construction tech-niques for ventilation and environmentalcontrol systems were based on systemsseveral decades old, engineers were con-cerned not only with their effectiveness,but also with the need to ensure that theywould be cost effective.

Solution

In 1969, under the auspices of the In-stitute for Rapid Transit (later mergedwith the American Transit Associationto form the American Public TransitAssociation), the transit industry,through a joint committee, produced adocument entitled "Guidelines for De-sign of Rapid Transit," focusing on this

issue. It became increasingly apparentthat a comprehensive plan was needed,aimed specifically at design for subwayenvironmental control.

The result was the development ofthe Subway Environmental Simulation(SES) design package, funded by a$3,500,000 grant from the Urban Mass

TR News, November–December 1987 17

Transportation Administration (UMTA).1

The participating transit systems donatedprofessional and support staff through anadvisory board to review and commentduring the life of the project.

The research findings resulted in apackage of design principles and an ac-companying computer simulation pro-gram that was confirmed by modelingand full-scale testing. The approach wasaided by proven technology in relateddesign fields that also used modelingtechniques, full-scale testing, and ad-vanced computer programming applica-tions.

Application

After four-and-a-half years of study anddevelopment, the results were releasedfor industry use and application. The

1The spectrum of talent required to developthis comprehensive design package con-sisted of a joint venture of Parsons Brincker-hoff Quade and Douglas, Inc.; DeLeuw,Cather and Company; and Kaiser Engineers.Supportive basic research and testing wasperformed by California Institute of Tech-nology's Jet Propulsion Laboratory and De-velopmental Sciences, Inc. Certain hardwaretesting support was provided by the GeneralElectric Company. Full-scale testing tookplace on the Toronto, Chicago, and Wash-ington, D.C., transit systems.

package consisted of two parts: SubwayEnvironmental Design Handbook (Vol.1), and Computer Programmers andUsers Manual (Vol. 2). The SES com-puter program is also available on tape.

Since the completion of the researchwork in 1975, there has been a steadyflow of requests for the computer tapesand the Computer Programmers andUsers Manual, plus instructional ses-sions at the U.S. DOT's TransportationSystems Center, which acts as the cus-todian of the documentation. Transitsystems around the world have used thesimulation and analytical tools in thedesign of their tunnel ventilation sys-tems. As recently as 1985, there havebeen instructional sessions and requestsfor the SES program and its 1981 revi-sions, which added capability for simu-lating smoke flow and control.

Benefits

At the time of completion of the userspackage, there was evidence that appli-cation during the project developmenthad produced savings approaching $5.5million in design, engineering, and con-struction costs of subway systems.These savings were realized by systemsunder construction in Atlanta, Wash-ington, D.C., and Baltimore.

Since then, savings in new subwayand tunnel design and construction inBuffalo, Pittsburgh, Los Angeles, Seat-tle, Dallas, Hong Kong, Singapore, andCaracas have exceeded the original costof research more than tenfold, accordingto conservative estimates.

Previously, the common practice wasto construct vent shafts between sta-tions. Using the added design capabilityfor simulating tunnel ventilation, thesemay no longer be needed. For example,the original design of a currentlyplanned rail transit system with 16 un-derground stations called for shafts ontunnel segments over 2 miles in length.At a typical shaft cost of $500,000 to $2million the elimination of about 12shafts would save up to $12 million.

An additional important benefit of theimproved ventilation design has beenthe increased margin of safety and im-proved environmental comfort that isprovided. Though this benefit is difficultto quantify in terms of dollars, it may bethe most tangible direct gain by the rid-ing public.