Tunnel Emer Egress & Mid-Train Fire_R3

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Tunnel Emergency Egress and theMid-Train Fire

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ABSTRACT

This paper provides both a means for tailoring the current rail transportation tunnel emergency egress

guidelines to the specifics of the individual system applications, and a strategy for improving the overall

fire-life safety of passengers/crew during a mid-train fire event. These dual objectives are accomplished

via the development of an equation based upon the time required to complete the various activities

associated with a train evacuation, and subsequently re-arranged to solve for the required distance

intervals between successive tunnel egress elements. The paper then provides examples of how this

equation may be put to use for three hypothetical rail systems, as well as a correction for one of the

examples as a result of a discussion on controlled evacuations. Finally, a parametric study is provided in

order to evaluate the relative impact of changing certain variables within the equation.

INTRODUCTION

The National Fire Protection Association (NFPA) Standard 130 entitled, ‘Fixed Guideway Transit and

Passenger Rail Systems’ includes guidelines for tunnel emergency egress provisions. The 2003 edition of

the standard denotes in paragraph 6.2.4.1 that, “emergency exits shall be provided from tunnels to a point of

safety”, and in paragraph 6.2.4.2 that, “within underground or enclosed trainways, the maximum distance

between exits shall not exceed 2500 ft (762 m).” The latter of these two guidelines is explained further in

paragraph A.6.2.4.2, which draws a parallel to the NFPA 101 Life Safety Code and its consideration of an

affected, or unavailable, exit in specifying 2500 ft (762 m) as the maximum permissible travel distance

between tunnel exits. However, via paragraph 6.2.4.3.1, NFPA 130’s 2003 edition also states that, “cross

passageways shall be permitted to be used in lieu of emergency exit stairways to the surface where

trainways in tunnels are divided by a minimum of 2 hour-rated fire walls or where trainways are in twin

bores”. Paragraph 6.2.4.3.2 of the standard goes on to provide seven conditions under which crosspassageways may be utilized in lieu of emergency exit stairways; these conditions are noted below:

(1) Cross passageways shall not be farther than 800 ft (244 m) apart;

(2) Openings in open passageways shall be protected with fire door assemblies having a fire protection

rating of 1-1/2 hours with a self-closing fire door;(3) A noncontaminated environment shall be provided in that portion of the trainway that is not involved

in an emergency and that is being used for evacuation;

(4) A ventilation system for the contaminated tunnel shall be designed to control smoke in the vicinity of

the passengers;

(5) An approved method shall be provided for evacuating passengers in the uncontaminated trainway;(6) An approved method for protecting passengers from oncoming traffic shall be provided; and,

(7) An approved method for evacuating the passengers to a nearby station or other emergency exit shall

be provided.

Figuring prominently among these conditions is the subject of the recommended distance between

successive cross passageways. The 2003 edition of NFPA 130 does not distinguish between the various

types of fixed guideway rail systems - i.e. subway, commuter rail or light rail, their associated train lengths,

the number of persons onboard the trains, or the size/growth rate of the design fire in recommending the

800 ft (244 m) interval. The 800 ft (244 m) guideline also pre-dates the expanded application of the NFPA

130 Standard from transit systems only - reference paragraph 3-2.4.3.a of the 1997 edition - to both transit

and passenger rail systems - reference paragraph 3-2.4.3.1 of the 2000 edition.



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However, the stated purpose of the NFPA 130 Standard, as indicated in paragraph 1.2 of the 2003

edition, as well as in previous editions, is to “establish minimum requirements …” for fire-life safety within

fixed guideway tunnel environments; therefore, the 800 ft (244 m) cross passageway spacing noted in

paragraph 6.2.4.3.2 (1) should be interpreted as written - as a ‘not-to-exceed’ value for fixed guideway

applications, and not as a constant design parameter to be uniformly applied to every conceivable rail

tunnel application. For specific rail tunnel systems, the individual parameters affecting emergency egress

should be evaluated to determine whether they merit NFPA 130’s minimum fire-life safety provisions, orwhether more extensive considerations are needed.

THE MID-TRAIN FIRE

The prospect of a mid-train fire is one of the more troubling fire-life safety scenarios from the

standpoints of both tunnel emergency egress and tunnel emergency ventilation. From the standpoint of

egress, a ‘mid-train’ fire can generally be classified as any event that tends to divide the incident

passenger/crew population into two distinct evacuation groups. If the incident area is presumed to coincide

with the length of the affected train car, then any fire onboard all but the two end-cars would constitute a

‘mid-train’ event. For an eight-car consist, a fire occurring onboard any of the middle six cars - or, 75% of

the train - would constitute a ‘mid-train’ event; for a twelve-car consist, a fire occurring onboard any of the

middle ten cars, see Figure 1 - or, approximately 83% of the train - would be considered a ‘mid-train’

event. If the incident area is presumed to be only a portion of the affected train car, then these percentages

would increase for each example given.

Mid-train End-CarEnd-Car

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Figure 1 - Mid-Train Cars for 12-Car Consist

Rail tunnel emergency ventilation systems are typically designed based upon ‘push-pull’ fan response

modes for end-car events. The typical emergency ventilation system is capable of developing the

longitudinal tunnel air velocity required to direct smoke flow away from the selected evacuation path, and

preventing smoke from ‘backlayering’ into that same path. These capabilities are consistent with the

emergency ventilation system design characteristics recommended in the 2003 edition of NFPA 130 for

fixed guideway transit and passenger rail systems - reference paragraphs 7.2.1 (1) and 7.2.1 (2). However,

in the case of the mid-train fire, two paths of passenger/crew evacuation are conceivable. And, while the

typical emergency ventilation system would be capable of meeting the NFPA 130 design standard for

passenger/crew safety in either direction, it is usually not capable of simultaneously meeting the NFPA 130

design standard for passenger/crew safety in both directions - unless it is designed as a ‘point-extract’

system, which it traditionally is not, due to space and cost considerations. {A point-extract system would

be theoretically capable of confining smoke flow to the incident car area, and thus, would permit immediate

and simultaneous evacuations of both passenger/crew groups - in opposite directions, see Figure 2.}

Therefore, detailed consideration of the various mid-train fire scenarios is warranted.

Direction

of evacuation

Direction

of evacuation

Continuous DuctOpen Damper

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Figure 2 - Point-Extract System for Mid-train Fire Scenario

Simultaneous evacuation of both passenger/crew groups.



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The emergency ventilation system response to a mid-train fire must be coordinated with the evacuation

plans of the passengers/crew; the operation of the tunnel fans to preserve ‘tenable’ - as defined by NFPA

130 Annex B - conditions in one evacuation path must not further endanger the group of passengers/crew

on the opposite side of the fire. Assuming that the mid-train fire renders the incident train car un-passable,

one of three emergency evacuation/ventilation scenarios is likely - each has its own specific benefits and

drawbacks, and other scenarios are possible. {The purpose of discussing these scenarios is to provideinsights into the dynamics of mid-train fire evacuations and the related, ventilation system operations.}

1. If the fire is in its early stages of development and the tunnel conditions on both sides of the incident

train are considered by the crew to be tenable, each of the two passenger/crew groups may be directed

to evacuate in opposite directions. See Figure 3. In this scenario, the tunnel fans would not be

activated during the simultaneous evacuations; only after one passenger group - most likely the group

with the shorter travel time - had reached a point of safety would fan operations be possible in support

of the other passenger/crew group’s evacuation. Tunnel ingress by emergency service personnel

should also be considered as part of the fan activation plan; ideally, emergency responders should enter

the tunnel on the upstream side - i.e. where the fans are in supply mode - of the fire.

Direction

of evacuation

Direction

of evacuation

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Figure 3 - Mid-train Fire Scenario #1

Simultaneous evacuation of both passenger/crew groups.

2. If the fire grows quickly and the tunnel conditions on one side of the incident train are considered to be

untenable - due, for example, to a significant tunnel grade and buoyancy-driven smoke flow, then the

passenger/crew group on the opposite end of the incident train would be directed to evacuate first. In

this scenario, the tunnel fans would not be activated during the initial evacuation - the operation of the

fans would pressurize the tunnel and may cause smoke flow into the occupied cars on the opposite end

of the train. After the first passenger/crew group had reached a point of safety, the fans could beoperated in support of the second group’s evacuation - in the opposite direction. See Figure 4. Again,

the ingress of emergency service personnel should be coordinated with the selected fan mode.

Direction

of evacuation

Initial evacuation,

Tunnel fans not activated.

Direction

of airflow

Latter evacuation,

Tunnel fans activated.

Direction

of evacuation

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3. If the fire grows quickly and the tunnel conditions on both sides of the incident train are considered by

the crew to be untenable, then the evacuation of the two passenger/crew groups could be conducted in

sequence. In this scenario, the tunnel fans would be operated in support of both the initial evacuation -

most likely by the group with the shorter travel time, and the latter evacuation. See Figure 5. Despite

any residual air pressure within the cars, the operation of the fans - in support of the initial evacuation -

may cause smoke flow into the opposite end of the train, which, at this time, would still be occupied.

Then, when the evacuation of the second passenger/crew group is beginning in the opposite direction,

a timely flow reversal by the tunnel fan system would be required.



Direction

of airflow

Initial evacuation,


Latter evacuation,


Direction

of evacuationDirection

of airflow

Direction

of evacuation

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The two most important aspects in each of these three mid-train fire scenarios are: the manner in which

the evacuations are organized/authorized, and the speed at which they occur. The first aspect is dependent

upon the preparedness of the operating authority - the train crew, in particular - for such events, and places

added importance upon: the development of emergency procedures, personnel training, and incident

communications. The second aspect is directly related to the number and proximity of emergency exits,

cross passageways or other points of tunnel egress, i.e. station platforms or portals. These two aspects are

also inter-connected because any delay in organizing the evacuations will tend to increase the overall time

needed to complete the evacuations, and therefore, expose a greater number of evacuees to smoke flow.

If the incident train happened to stop at a location where it straddled a means of tunnel egress, then a

timely evacuation of one passenger group via that emergency exit/cross passageway would tend to

minimize human exposure to smoke during the mid-train fire event. However, if the incident fire issufficiently large, or its location happened to directly coincide with that of an emergency exit or cross

passageway, then the fire may prevent use of that nearest means of egress. See Figure 6. In this case, the

distance to the next available emergency exit or cross passageway would be an important consideration for

both passenger/crew evacuation groups. In the context of this worse-case positioning of train/fire/exit, an

equation was developed for the dual purpose of tailoring the NFPA 130 tunnel egress guidelines to the

individual rail system application, and improving fire-life safety - the emergency egress provisions, in

particular - during the mid-train fire event. The level of conservatism associated with this worse-case event

is appropriate for such static fire-life safety provisions as emergency exits and/or cross passageways, since

the number/location of each cannot be altered for specific events.

Direction

of evacuationDirection

of evacuation

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Figure 6 - Mid-train Fire Aligned with Exit,

Fire location prevents use of nearest egress path.

EQUATIONS

The basis for the equation developed was a simple compilation of the time-dependent activities

associated with the evacuation of the first passenger/crew group from a worse-case, mid-train fire event. In

equation format, the summation of these activities was then set against the time associated with the

initiation of the second passenger/crew group’s evacuation in a sequenced emergency egress operation for a

‘true’ - i.e. at the exact mid-point of the consist - mid-train event. See Equation 1.0. The evacuation of thesecond passenger/crew group, which was presumed to start before the design fire reaches a ‘flashover’

state, would be supported by the operation of the tunnel emergency ventilation system.

t discovery + t comms + t initial evac + t fans active = t latter evac ≤ t full mode ≤ t flashover (1.0)

where:

t discovery = the time associated with the discovery of the mid-train fire, in minutes

t comms = the time needed to communicate the details of the mid-train fire between the incident train and the

operations control center, and initiate the evacuation of the first passenger/crew group, in minutes



t initial evac = the time needed to evacuate the first passenger/crew group from the incident tunnel, in minutes1

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t fans active = the run-up time of the tunnel fans preceding the evacuation of the second group, in minutes

t latter evac = the time at which the second passenger/crew group’s evacuation is commenced, in minutes

t full mode = the time at which the tunnel fans reach full operational mode, in minutes

t flashover = the time at which the mid-train fire reaches flashover, in minutes

The first two terms in Equation 1.0, t discovery and t comms, are elapsed-time entries that may be determinedeither via training exercises or, estimated for the individual rail system application based upon such factors

as: train length, crew size, vehicle fire alarm/extinguishing provisions, personnel emergency procedures,

etc. {The identification of the incident train car location is essential to the recognition of a mid-train fire

event. For best emergency response planning, the location of the incident train car should also be quickly

determinable - either, locally or remotely - versus both the nearby tunnel egress provisions, and the closest

mechanical ventilation shafts.}

The time required to safely evacuate the first passenger/crew group, t initial evac, can be estimated through

use of three additional terms: i) the time required for the first evacuee in the group to reach the most

constricting element in the evacuation path, or t first evacuee; ii) the time required for the entire group of

evacuees to pass through the most constricting element in the evacuation path, or t constrict element ; and, iii) the

time required for the last evacuee in the group to travel from the most constricting element in the

evacuation path to a point of safe refuge, or t last evacuee. Refer to Equation 2.0.

t initial evac = t first evacuee + t constrict element + t last evacuee (2.0)

The time required for the first evacuee in the group to reach the most constricting element in the

evacuation path can be computed by dividing the distance traveled, D fe, by the speed of travel, V , or D fe /V .

If the most constricting element in the evacuation path is either the vehicle door or the bench walkway, then

the length of travel for the first evacuee to reach this element, and consequently, the term D fe /V , will have a

relatively minor impact upon the equation.

Then, the time required for the entire group of evacuees to pass through the most constricting element

in the evacuation path can be computed by dividing the incident train’s evacuee population, P t , by the

product of the egress flow capacity through the most constricting element, Q, and the usable width, wc, of

the element, or P t /(Qwc ). For the true mid-train event, however, the initial evacuee population would

consist of one-half of the train’s passenger/crew load, or P t /2. An additional, non-dimensional parameter,

y, can be included in the denominator of this term to reflect the number of active egress elements during the

initial evacuation; therefore, the final form of this term in the equation is: P t /(2Qwc y).Finally, the time required for the last evacuee in the group to travel from the most constricting element

in the evacuation path to a point of safe refuge would then be the distance of travel, Dle, divided by the

speed of travel, V , or Dle /V . In order to relate this term to the proper spacing of tunnel egress elements, the

parameter Dle can be represented by the distance that must be traveled to reach a tunnel egress element, Dl ,

minus one-half of the train length, Lt /2, divided by the number of active egress elements, y, or: Dle = Dl -

( Lt /2y). However, in order to accurately reflect the distance to each available egress element during the

initial evacuation, the term Dl can be represented by the product of the number of active egress elements

during the initial evacuation, y, and the required distance between the successive egress elements, D x.

Therefore, the final form of this term in the equation is: (yD x - (Lt /2y))/V , and the re-written form of

Equation 2.0 is then:

t initial evac = D fe /V + P t /(2Qwc y) + (yD x - (Lt /2y))/V (2.1)

Inserting the expanded form of t initial evac back into Equation 1.0 yields:

t discovery + t comms + D fe /V + P t /(2Qwc y) + (yD x - (Lt /2y))/V + t fans active = t latter evac ≤ t full mode ≤ t flashover (1.1)

As for the remaining term on the left-hand side of Equation 1.1, the elapsed-time entry t fans active was

included to reflect the presumption that the latter evacuation - that of the second passenger/crew group -

would occur under the smoke-flow protection of the emergency ventilation system, and that the tunnel fans

would have a run-up time before reaching full mode capability. Per paragraph 7.2.1 (3) of NFPA 130’s

2003 edition, “the emergency ventilation system shall be designed to … be capable of reaching full



operational mode within 180 seconds”. The impact of this term, however, on the overall computation can

be minimized if the tunnel fan system is activated in advance of commencing the second passenger/crew

group’s evacuation. However, activating the tunnel fan system prior to the completion of the first group’s

evacuation will expose some of those evacuees to smoke flow - which, at this point, may be diluted due to

the impact of the tunnel fan operations.

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It is presumed that the commencement of the second passenger/crew group’s evacuation, t latter evac, does

not exceed the time at which the tunnel fans reach full operational mode capability, t full mode, and that full-mode tunnel fan operations precede the point when the mid-train fire reaches its flashover condition, t flashover

- the point at which all combustible materials within the affected train car are presumed to be engaged in

the fire. Typical fire size data for selected rail vehicles is provided by the American Society of Heating,

Refrigerating and Air-Conditioning Engineers (ASHRAE) in Chapter 13 of the HVAC Applications

Handbook under the heading ‘Rapid Transit’, sub-heading ‘Emergency Ventilation’. Fire growth rate data

is both incident- and vehicle-specific; consequently, it is not provided in the Handbook.

Re-configuring Equation 1.1 once more to solve for the desired variable, D x, the required distance

between successive tunnel egress elements, yields:

D x = [V x (t latter evac – (t discovery + t comms + D fe /V + P t /(2Qwc y) + t fans active )) + (Lt /2y)]/y (1.2)

where the definitions provided for Equation 1.0 apply, and:

D x = the required distance between successive tunnel egress elements, in feet (meters), see Figure 7

V = the speed of travel, in feet per minute, fpm (meters per minute, m/min) D fe = the distance traveled by the first evacuee in the group to reach the most constricting element in the

path of evacuation, in feet (meters)

P t = the total number of passengers/crew onboard the incident train, in persons

Q = the egress flow capacity through the most constricting element in the path of evacuation, in persons

per inch per minute, pim (persons per millimeter per minute, p/mm-min)

wc = the usable width of the most constricting element in the path of evacuation, in inches (millimeters)

y = the number of active egress elements during the initial evacuation, non-dimensional

Lt = the total length of the incident train, in feet (meters)

Lt

Dle

D x

D fe

wc

Not

Available

Egress

#1

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Figure 7 - Definition of Terms for Equation 1-2.

ANALYSES

Of all the variables shown in Equation 1.2, only Q, the egress flow capacity, and V , the egress travel

speed, are not application-specific and, can thus be standardized.

Within Chapter 5, the 2003 edition of the NFPA 130 Standard provides factors for use in computing

emergency egress times. Though specifically intended for station egress planning, the NFPA 130 factors

may provide insight towards estimating passenger evacuation rates from tunnels. Among these factors are:

an egress flow capacity of 2.27 pim (0.0893 p/mm-min) and an egress travel speed of 200 fpm (61 m/min)

on platforms, corridors and ramps sloped at less than four percent. These general factors may be

considered as reflective of timely/orderly station evacuations, in that, they do not specifically address

slower-moving persons, such as children, the elderly, mobility-disadvantaged/handicapped individuals or

those injured during the event - each of whom may reduce the overall egress flow capacity or travel speed



of the evacuation group. Computer modeling may be used to provide more realistic predictions of

passenger egress flow capacity and travel speed in tunnels.

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Since these factors are specifically intended for station planning in the current edition of the NFPA 130

Standard, they should be considered as non-ideal for tunnel evacuation analyses. For example, paragraph

5.5.3.3.1.1 recommends that egress paths should be a minimum of 5 ft 8 in (1.73 m) wide, and paragraph

5.5.3.3.1.2 recommends that when computing capacity available, 1 ft (0.3048 m) should be deducted at

each side wall and 1 ft 6 in (0.4572 m) from each platform edge. A traditional 30-inch-wide (762-millimeter-wide) tunnel bench walkway is significantly less than the minimum egress path width

recommended in paragraph 5.5.3.3.1.1, and provides no usable width for egress flow capacity calculations

when evaluated against the recommendations of paragraph 5.5.3.3.1.2. It should be recognized that in

order to achieve a usable walkway width of 30 inches (762 millimeters), a 60-inch-wide (1524-millimeter-

wide) tunnel bench would be required. Nevertheless, in the absence of other specific flow capacity or

travel speed data for tunnel egress applications, Q will be assumed as 2.27 pim (0.0893 p/mm-min), and V

will be taken as 200 fpm (61 m/min) in the following analyses.

The balance of the data required by Equation 1.2 was selected for three distinctive rail system

classifications: commuter rail, subway and light-rail. The data entries selected were purely hypothetical,

and not intentionally representative of any one particular fixed guideway tunnel system.

Train Data Inputs

The train data entries associated with Equation 1.2 include: the train length, Lt ; the passenger/crew

load, P t ; the distance to the most constricting element in the evacuation path, D fe; and, the time for the fire

to reach flashover, t flashover . In the analyses that follow, these data entries were arbitrarily-selected for each

hypothetical rail system application, and were not intended to represent either any one particular fixed

guideway system, or an average of several. The entries were, however, selected in a manner that attempted

to address the comparative differences between the three rail system classifications. For example, the

variations in the train length and passenger/crew load entries were based on the assumptions that the

commuter rail system would have the longest train for the largest passenger/crew load, and that the light-

rail system would have the shortest train for the smallest passenger/crew load. The related subway system

entries fall in between the commuter and light-rail system entries.

It was also assumed that each of the respective commuter rail, subway and light-rail trains had side

doors for easy access to the tunnel bench walkway, and that these double-width doors were wider than the

tunnel bench walkway - which made the walkway the more constricting element in the path of evacuation.

The tunnel bench walkway was, in fact, assumed to be the narrowest, most constricting passage within the

entire evacuation path. Therefore, the distance traveled by the first evacuee in the group to reach the mostconstricting element was approximated as the distance from the centerline of the train car to the centerline

of the bench walkway. These entries were varied for the individual rail system applications based upon

hypothetical train widths - where the commuter rail system was presumed to have the widest train, the

light-rail system the narrowest, and the subway system train width was midway between the other two.

For the fire flashover time, a distinction was made in terms of the actual location of the fire. An

assumption was made that the commuter rail train experienced a coach fire, whose close proximity to the

majority of combustible components onboard the train resulted in a relatively short time to reach flashover.

Conversely, both the subway and light-rail system trains were presumed to have undercarriage fires, where

the growth/spread of the fire to the combustible components within the coach area - which enable it to

reach its flashover state - was delayed by fire-rated vehicle flooring. In all three cases, it was assumed that

the mid-train fire, either directly or indirectly, caused the incident train to stop within the tunnel, and was

serious enough to necessitate an evacuation. It is important to note that the time required for the fire to

reach flashover is not an active variable within Equation 1.2; t flashover serves only as a limiting factor on thetime available to both complete the evacuation of the initial passenger/crew group, and, at least, commence

the evacuation of the second passenger/crew group. The evacuation of the second group is also presumed

to occur under the protection of an active tunnel emergency ventilation system.

Elapsed-Time Entries

The elapsed-time data entries in Equation 1.2 include: the time related to the fire discovery, t discovery; the

time needed for pre-evacuation communications, t comms; and, the time associated with the activation of the

tunnel fan system, t fans active. With the exception of the fan activation time - which has the aforementioned



limiting factor of 180 seconds via NFPA 130 paragraph 7.2.1 (3), these entries are entirely specific to the

individual rail system application. For the sake of variation in the analyses, these hypothetical data entries

were varied in accordance with the assumptions described below:

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It was assumed that the commuter rail system conductor’s greater mobility - i.e. for ticket-checking

activities, etc - would lend itself towards a more timely fire discovery than in a subway system.

Furthermore, a light-rail system may be automated - which may lend itself to the least timely fire discovery.

It was also presumed that subway systems, due to their longer association with the guidelines of the NFPA130 Standard, would have more efficient emergency communications than either the commuter rail or light-

rail systems. Finally, in recognition of its greater passenger/crew load, it was assumed that the commuter

rail system would activate the tunnel fan system earlier than either the subway or the light-rail systems.

However, as previously noted, activating the tunnel fan system prior to the completion of the first

passenger/crew group’s evacuation may expose some of those evacuees to hazardous smoke flow.

The time selected for the commencement of the second passenger/crew group’s evacuation in each

individual rail system application was based upon the limitations identified in Equation 1.1, where t latter evac

was to precede both the time at which the tunnel fans reached full mode operation, t full mode, and the time at

which the fire reached its flashover state, t flashover . Beyond that, it should also be recognized that the mid-

train fire is burning from time = 0 seconds in these scenarios/analyses, and that t flashover should not be

considered as a grace period for completing all decision-making, communications, emergency systems

response planning and personnel evacuations. From the moment the mid-train fire begins, the incident

passengers/crew are in danger; therefore, the variable t latter evac should be set as low as deemed practical.

Results

The results of six particular calculations are presented in Table A. Unless otherwise indicated,

Equation 1.2 was solved for the required distance between successive tunnel egress elements, D x.

Commuter Calc #1 presents the results of an analysis for a hypothetical commuter rail system application;

Commuter Calc #2 demonstrates the impact of adding a second active egress element during the initial

passenger/crew evacuation. Subway Calc #1 presents the results of an analysis for a hypothetical subway

system application; Subway Calc #2 provides the result of back-calculating t latter evac using the NFPA 130-

recommended guideline for cross passageway spacing, 800 ft (244 m), as an input for D x. Light-Rail Calc

#1 presents the results of an analysis for a hypothetical light-rail system application; Light-Rail Calc #2

provides the result of back-calculating t latter evac using the NFPA 130-recommended guideline for cross

passageway spacing, 800 ft (244 m), as an input for D x.

Table A - Results of Analyses for Equation 1.2

Variable Units

Commuter

Calc #1

Commuter

Calc #2

Subway

Calc #1

Subway

Calc #2

Light-Rail

Calc #1

Light-Rail

Calc #2

t flashover min 10 10 30 30 30 30

t latter evac min 10.0 10.0 12.5 13.43292 15.0 13.35885

t discovery min 0.5 0.5 0.75 0.75 1.0 1.0

t comms min 1.0 1.0 0.5 0.5 1.5 1.5

t fans active min 0 0 1.5 1.5 3.0 3.0

V fpm

(m/min)

200

(61)

200

(61)

200

(61)

200

(61)

200

(61)

200

(61)

D fe ft (m) 6 (1.83) 6 (1.83) 5 (1.52) 5 (1.52) 4 (1.22) 4 (1.22)

P t persons 1500 1500 1000 1000 500 500

Q pim

(p/mm-min)

2.27

(0.0893)

2.27

(0.0893)

2.27

(0.0893)

2.27

(0.0893)

2.27

(0.0893)

2.27

(0.0893)

wc in (mm) 30 (762) 30 (762) 27 (686) 27 (686) 24 (610) 24 (610)

Lt ft

(m)

900

(274.3)

900

(274.3)

600

(182.9)

600

(182.9)

300

(91.5)

300

(91.5)

y none 1 2 1 1 1 1

D x ft

(m)

-58.64

(-17.9)

408.84

(124.6)

613.41

(187.0)

800

(244)

1128.23

(343.9)

800

(244)

Calculated values are shown in shaded cells.35



DISCUSSION1

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The focal point of the analyses presented in Table A is the computed distance between successive

tunnel egress elements, D x. The value of this term was determined using Equation 1.2 for the analyses

entitled: Commuter Calc #1, Commuter Calc #2, Subway Calc #1 and Light-Rail Calc #1. In the remaining

two analyses, Subway Calc #2 and Light-Rail Calc #2, D x was assumed to be 800 ft (244 m) for the sake of

comparison with the guidelines in the 2003 edition of the NFPA 130 Standard. Each of the respective rail

systems analyses is discussed below:Upon inspection of the results for Commuter Calc #1, it is evident that a negative value was produced

for the distance between successive tunnel egress elements, D x = -58.64 ft (-17.9 m). This result simply

means that the combination of train data, elapsed time entries and passenger flow capacity/travel speed

inputs to Equation 1.2 exceeded the time limit imposed on the analysis via the data input for t latter evac and

t flashover . Comparing the inputs to Commuter Calc #1 with that of the subway and light-rail calculations, it is

also evident that the summation of the elapsed time entries, t discovery, t comms and t fans active, were smallest, and

that the usable width of the tunnel bench walkway was greatest for the commuter rail calculation.

Therefore, the factors that contributed to this negative result were mainly the number of passengers/crew

involved in the initial evacuation, and the growth rate of the mid-train fire. The results of Commuter Calc

#1 were included in Table A to make a distinct point: that a single means of tunnel egress may not be

sufficient for evacuation of the first passenger/crew group based upon the combination of inputs to

Equation 1.2.

Hence, the variable ‘ y’ in Equation 1.2 was utilized in Commuter Calc #2 to introduce a second meansof tunnel egress during the first passenger/crew group’s evacuation. This improvement generated the

desired positive result for the distance between successive tunnel egress elements, D x = 408.84 ft (124.6 m)

- but, with the caveat that an equal number of evacuees were presumed to flow through each active exit, see

Figure 8. The significance of this result is that the specific combination of train data, elapsed time entries

and passenger flow capacity/travel speed inputs to Equation 1.2 for the commuter rail analysis generated an

interval between successive egress elements that was roughly one-half the maximum distance

recommended by NFPA 130. This is not to say that all commuter rail applications will require twice the

number of tunnel egress elements as that recommended in the 2003 edition of the Standard, but it does

signify that certain combinations of rail system data may necessitate greater tunnel egress provisions than

those cited by NFPA 130 in order to safely evacuate passengers/crew during a mid-train fire event.

375 persons

375 persons

Dx = 408.84 ft

(124.6 m)

Egress

#1Egress

#2

Dx = 408.84 ft

(124. 6 m)

Lt = 900 ft

(274.3 m)

Not

Available

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Figure 8 - Mid-Train Fire Results of Commuter Calc #2

The results of Subway Calc #1 indicate what the distance between successive tunnel egress elements,

D x = 613.41 ft (187.0 m), would be for a different combination of Equation 1.2 inputs, see Figure 9.

Despite greater elapsed time for both fire discovery and fan activation, and the selection of a narrower

tunnel bench width, the subway analysis generated greater spacing between tunnel egress elements than did

the commuter rail analyses. This was largely attributed to the reduced number of passengers/crew, P t ,

involved in the subway train evacuation and the greater time input for t latter evac. In the case of the latter

variable, 12.5 minutes was randomly selected as the time to commence the evacuation of the second

passenger/crew group - even though the mid-train fire did not reach flashover until 30 minutes of time had



elapsed. This relatively conservative selection of t latter evac data reflects the fact that the mid-train fire is

growing from time = 0 seconds.

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Dx = 613.41 ft

(187.0 m)

Egress

#1

Lt = 600 ft

(182.9 m)

Not

Available

500 persons

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Figure 9 - Mid-Train Fire Results of Subway Calc #1

Subway Calc #2 was completed to check the results of Subway Calc #1 against the current NFPA 130guidelines for tunnel cross passageway spacing. To do this, Equation 1.2 was re-arranged to solve for t latter

evac, while D x was taken to be 800 ft (244 m). The predictable result was that t latter evac increased by slightly

less than a minute to account for the additional 186.59 ft (57.0 m) of tunnel bench travel at 200 fpm (61

m/min). The decision as to whether faster, 12.5 minutes versus 13.4 minutes via reduced egress element

spacing, initial evacuations are warranted would ultimately rest with the authority having jurisdiction

(AHJ) for the individual subway system.

The results of Light-Rail Calc #1 indicate what the distance between successive tunnel egress

elements, D x = 1128.23 ft (343.9 m), would be for another combination of Equation 1.2 inputs, see Figure

10. Despite the largest data inputs for fire discovery, communications and fan activation times, and the

selection of the narrowest usable width for tunnel bench travel, the light-rail analysis generated greater

spacing between tunnel egress elements than in either of the other analyses. This was largely attributed to

the small number of passengers/crew, P t , involved in the light-rail train evacuation and the 15 minute

timeframe input for t latter evac. Even though the mid-train fire wasn’t presumed to reach flashover until 30minutes of time had elapsed, 15 minutes was randomly selected as the time to commence the evacuation of

the second passenger/crew group to reflect the fact that the mid-train fire is growing from time = 0 seconds.

Dx = 1128.23 ft

(343.9 m)

Egress

#1

Lt = 300 ft

(91.5 m)

250 persons Not

Available

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Figure 10 - Mid-train Fire Results of Light-Rail Calc #1

The significance of this result is that this specific combination of train data, elapsed time entries and

passenger flow capacity/travel speed inputs to Equation 1.2 for the light-rail analysis generated an interval



between successive egress elements that was almost fifty-percent greater than the maximum distance for

cross passageway spacing recommended by NFPA 130. This is not to say that all light-rail applications

will require 50% fewer tunnel egress elements than that recommended in the 2003 edition of the Standard,

but it does signify that certain combinations of rail system data may require fewer tunnel egress provisions

than those cited by NFPA 130, and still have sufficient means available to safely evacuate passengers/crew

during a mid-train fire event.

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As in the subway analyses, Light-Rail Calc #2 was completed to check the results of Light-Rail Calc#1 against the current NFPA 130 guidelines for tunnel cross passageway spacing by taking D x as 800 ft

(244 m), and solving for t latter evac. The predictable result was that t latter evac decreased by about 1.6 minutes

to account for the reduction of 328.23 ft (99.9 m) in tunnel bench travel at 200 fpm (61 m/min). The

decision as to whether slower, 15.0 minutes versus 13.3 minutes via increased egress element spacing,

evacuations are warranted would ultimately rest with the AHJ for the individual light-rail system.

Controlled Evacuations

Regardless of the manner in which the evacuation occurs during a train fire, emergency egress should

be ‘controlled’ - that is, organized and led by a qualified member of the crew. Upon reporting the details of

the event to an operations control center and receiving evacuation orders from same, crew member(s)

should be expected to proceed toward the door(s) at which the passengers will exit the train, and assume a

leadership position for the group of evacuees. In addition to achieving a sense of order, crew-based

leadership of the evacuation would be beneficial in terms of: adhering to the instructions of the operations

control center, recognizing tunnel signage (including that for the egress elements), avoiding other sources

of harm and continuing the flow of evacuees towards their ultimate destination - be it a station, portal, non-

incident tunnel/rescue train or the surface level, via an exit stair.

For all of the analyses in Table A except Commuter Calc #2, the manner of the controlled evacuation

from the mid-train fire would be similar - i.e. the evacuations of both the first and second passenger groups

would be led by a different crew member, in opposite directions, towards a single tunnel egress element. In

Commuter Calc #2, however, the presence of the second active egress element during the evacuation of

each passenger/crew group would have a tangible effect on the manner in which the evacuation is

controlled, and thus upon the desired result, D x. The form of Equation 1.2 presumes an equal distribution

of the first evacuation group between the two active egress elements; when, in fact, the actual distribution

would be determined by the manner in which the initial evacuation is controlled - which can be very

incident-specific.

To show the dependence of tunnel egress element spacing upon the manner by which the evacuation is

controlled, the results of Commuter Calc #2 were reconsidered based on the assumption that the evacueeswould exit the tunnel via the closest egress element in their forward path. With this assumption, the even

distribution of evacuees between the two active egress elements that is inherent to Equation 1.2 was

adjusted for the percentage length of train with respect to the location of the egress elements. Since

Commuter Calc #2 has a train length, Lt , of 900 ft (274.3 m) and a calculated, tunnel egress element

spacing, D x, of 408.84 ft (124.6 m), the percentage, %, of first evacuees that can be assumed to utilize the

nearer egress element in this example would be:

% = D x /( Lt /2) x 100 = 408.84 ft /(900 ft/2) x 100 = 90.85

{or, % = D x /( Lt /2) x 100 = 124.6 m /(274.3 m/2) x 100 = 90.85}

Since there are P t /2, or 750, evacuees in the first group, then about 0.9085 x 750 = 681 persons would

attempt to use the nearer of the two egress elements. A simplified version of Equation 1.1 was created to

evaluate the time needed to complete this controlled evacuation:

t discovery + t comms + D fe /V + P z /(Qwc ) + D z /V + t fans active = t latter evac ≤ t full mode ≤ t flashover (1.1a)

where the variables are similar to Equation 1.1, except:

P z = number of passengers/crew using the nearer tunnel egress element, in persons

y = 1, since only one egress element is involved in the calculation

D z = the distance of travel along the tunnel bench walkway to the nearest egress element, in feet (meters)

Lt = 0 ft (0 m), since the egress element being evaluated is within the length of the train



Solving Equation 1.1a for t latter evac with P z = 681 persons, D z = 1.0 ft (0.3048 m) assuming a best-case

scenario of a nearly coincident train car door and tunnel exit door, and the other data inputs taken from

Commuter Calc #2 yielded 11.54085 minutes - which exceeded the timeframe associated with fire

flashover t

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flashover = 10 minutes, by approximately 1.5 minutes. Therefore, with the controlled evacuation

based upon percentage evacuee flow to the nearest forward exit, the distance between successive tunnel

egress elements must be reduced further in order to achieve the 10 minute timeframe required for t latter evac.

To determine the maximum number of evacuees, P z’ , that can use the nearer of the two active tunnel egresselements within 10 minutes, Equation 1.1a can be re-arranged and simplified once more as:

P z‘ = (Qwc )[t latter evac – (t discovery + t comms + D fe /V + D z /V + t fans active )] (1.1b)

With t latter evac = 10 min, D z = 1.0 ft (0.3048 m) and the other data inputs taken from Commuter Calc #2,

Equation 1.1b yielded P z‘ = 576 persons. Then, the percentage, %’ , of first evacuees who could utilize the

nearer egress element within a 10-minute timeframe would be:

%’ = P z’ /( P t /2) x 100 = 576/(1500/2) x 100 = 76.80

Finally, solving for the percentage train length-adjusted tunnel egress element spacing, D x’ , based upon

the maximum number of evacuees that can utilize the nearest active egress element within a 10-minute

timeframe yielded:

D x‘ = ( Lt /2) x (%’/100) = (900 ft/2) x (76.80/100) = 345.60 ft

{ or, D x‘ = ( Lt /2) x (%’/100) = (274.3 m/2) x (76.80/100) = 105.4 m}, see Figure 11

Dx’ = 345.60 ft

(105.4 m)

Egress#1Egress#2

Dx’ = 345.60 ft

(105.4 m)

Lt = 900 ft

(274.3 m)

NotAvailable

174 persons

576 persons

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Figure 11 - Different Manner of Controlled Evacuation for Commuter Calc #2

Thus, the impact of reconsidering the results for Commuter Calc #2 based upon a different assumption

for the controlled evacuation served to further reduce the interval spacing between successive tunnel egress

elements from 408.84 ft (124.6 m) to 345.60 ft (105.4 m). This is not to say that the ‘percentage train

length’ method of approximating the controlled evacuation is more accurate than the equal distribution

method that is inherent to Equation 1.2. The purpose of this example was to demonstrate that the manner in

which the controlled evacuation is carried out may influence computations of tunnel egress element spacing

- when determined as a function of mid-train fire evacuation times.It is ultimately up to the individual rail system operator and the authority having jurisdiction to

determine the manner in which train evacuations will be remotely-organized from an operations control

center, and locally-controlled by the crew member(s). Once determined, the impact of the controlled

evacuation upon the results of Equation 1.2-based analyses can be computed. The controlled evacuation

method(s) should then become part of the emergency procedures - on which both the system operators and

the train crew should be trained and practiced - for tunnel fire events. Emergency responders should also

be cognizant of the manner in which the incident train evacuation is to be controlled, so that firefighter

ingress and paramedic resources can be directed to the proper location(s).



PARAMETRIC STUDY1

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The results of the Equation 1.2 analyses depend upon all of the data inputs shown in Table A, though

some inputs affect the results more than others. Therefore, a parametric study was completed in order to

demonstrate the effects of changing the values of certain variables in the Equation 1.2-based analyses. Two

variables were altered for each rail system type - generating a new Calc #3 and a new Calc #4, respectively,

for each application. The basis for Commuter Calcs #3 and #4 was the original data from Commuter Calc

#2; the basis for Subway Calcs #3 and #4 was the original data from Subway Calc #1; and, the basis forLight-Rail Calcs #3 and #4 was the original data from Light-Rail Calc #1. The results of the parametric

study are presented in Table B.

In Commuter Calc #3, the time needed to communicate the details of the mid-train fire was increased

to 2.0 minutes; no specific reason for the additional time is necessary for the parametric study, but it may

be a function of either mis-communication or unpreparedness. In Commuter Calc #4, the egress flow

capacity was reduced to 1.82 pim (0.0716 p/mm-min); this parametric analysis relates to the

aforementioned uncertainties inherent to using NFPA 130 station egress guidelines for tunnel analyses.

In Subway Calc #3, the usable width of the most constricting element in the path of evacuation was

increased to 29 inches (737 mm). Though it is not possible to change the width of an egress element in the

course of an event, this parametric analysis was completed to highlight the significance of this variable in

Equation 1.2. In Subway Calc #4, the egress travel speed was reduced to 160 fpm (48.8 m/min); this

parametric analysis relates to the aforementioned uncertainties inherent to using NFPA 130 station egress

guidelines for tunnel analyses.In Light-Rail Calc #3, the length of the incident train was increased to 330 feet (100.6 m). This

parametric study reflects the consideration that within the same rail transportation system, trains of

differing lengths may be operated at different times of the day, or week. In Light-Rail Calc #4, the evacuee

population was reduced to 450 persons to address the fact that the number of passengers/crew onboard the

incident train will also vary depending upon the time of day, or week.

Table B - Results of Parametric Study

Variable Units

Commuter

Calc #3

Commuter

Calc #4

Subway

Calc #3

Subway

Calc #4

Light-Rail

Calc #3

Light-Rail

Calc #4

t flashover min 10 10 30 30 30 30

t latter evac min 10.0 10.0 12.5 12.5 15.0 15.0

t discovery min 0.5 0.5 0.75 0.75 1.0 1.0t comms min 2.0 1.0 0.5 0.5 1.5 1.5

t fans active min 0 0 1.5 1.5 3.0 3.0

V fpm

(m/min)

200

(61)

200

(61)

200

(61)

160

(48.8)

200

(61)

200

(61)

D fe ft (m) 6 (1.83) 6 (1.83) 5 (1.52) 5 (1.52) 4 (1.22) 4 (1.22)

P t persons 1500 1500 1000 1000 500 450

Q pim

(p/mm-min)

2.27

(0.0893)

1.82

(0.0716)

2.27

(0.0893)

2.27

(0.0893)

2.27

(0.0893)

2.27

(0.0893)

wc in (mm) 30 (762) 30 (762) 29 (737) 27 (686) 24 (610) 24 (610)

Lt ft

(m)

900

(274.3)

900

(274.3)

600

(182.9)

600

(182.9)330

(100.6)

300

(91.5)

y none 2 2 1 1 1 1

D x ft(m)

308.84(94.1)

228.51(69.7)

725.94(221.3)

549.73(167.6)

1143.23(348.5)

1220.01(371.9)

Altered values are shown in bold type. Calculated values are shown in shaded cells.29

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As compared with the results of Commuter Calc #2, increasing the communications time, t comms, in

Commuter Calc #3 from 1.0 to 2.0 minutes served to reduce the distance between successive egress

elements, D x, from 408.84 ft (124.6 m) to 308.84 ft (94.1 m). This is a predictable result since the elapsed

time entries, including t discovery and t fans active, inversely affect the outcome - either positively or negatively -

as a function of the travel speed, V, divided by the number of active egress elements, y. In this case, a 1.0

minute increase multiplied by V/y reduced the distance between successive egress elements by 100 ft (30.5



m). Changes to the other time-dependent variables in Equation 1.2 will generate similar results, whereby

the impact upon the calculation can be determined as the net change in the variable multiplied by V/y.

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In Commuter Calc #4, a ~20% reduction in the egress flow capacity [1.82 pim (0.0716 p/mm-min) vs

2.27 pim (0.0893 p/mm-min)] through the most constricting element in the evacuation path yielded a ~44%

reduction in the egress element spacing [228.51 ft (69.7 m) vs 408.84 ft (124.6 m)] - with all other values in

Commuter Calc #2 held constant. This is a logical result because a reduction in the egress flow capacity

lengthens the time needed for the evacuees to pass through the most constricting element in their path, andtherefore necessitates closer egress element spacing to achieve the same overall evacuation time. This

parametric analysis was included to show the impact of the egress flow capacity, Q - which affects

Equation 1.2 as a function of the passenger/crew load, P t , and the usable width, wc, of the most constricting

element - on the overall result.

As compared with the results of Subway Calc #1, increasing the usable width of the most constricting

element in Subway Calc #3 from 27 in (686 mm) to 29 in (737 mm) served to increase the distance

between successive egress elements, D x, from 613.41 ft (187.0 m) to 725.94 ft (221.3 m). This is a logical

result because an increase in the usable width reduces the time needed for the evacuees to traverse the most

constricting element in their path, and therefore permits wider egress element spacing to achieve the same

overall evacuation time. This parametric analysis was included to show the impact of the usable width, wc,

- which affects Equation 1.2 as a function of the egress flow capacity, Q, and the passenger/crew load, P t , -

on the overall result.

In Subway Calc #4, a ~20% reduction in the evacuee’s travel speed [160 fpm (48.8 m/min) vs 200 fpm

(61 m/min)] netted only a ~10% reduction in the egress element spacing [549.73 ft (167.6 m) vs 613.41 ft(187.0 m)] - with all other values in Subway Calc #1 held constant. This is a predictable result because

slower walking speeds correspond to longer travel times, and require closer egress element spacing to

achieve the same overall evacuation time. The imbalance between the percentage change in the variable,

and the percentage change in the result is attributed to the weight of the various terms in Equation 1.2 -

where the variables that were held constant between Subway Calc #1 and Subway Calc #4 would seem to

contribute more to the calculated result.

As compared with the results of Light-Rail Calc #1, increasing the length of the train in Light-Rail

Calc #3 from 300 ft (91.5 m) to 330 ft (100.6 m) served to increase the distance between successive egress

elements, D x, from 1128.23 ft (343.9 m) to 1143.23 ft (348.5 m). This is a predictable result because the

train length affects the outcome - either positively or negatively - as a function of itself over two times the

number of active egress elements, Lt /2 y. In this case, a 30 ft (9.1 m) increase divided by the product of (2 y,

with y = 1) increased the distance between successive egress elements by 15 ft (4.6 m).

In Light-Rail Calc #4, a 10% reduction in the passenger/crew load [450 persons vs 500 persons] nettedan ~8% increase in the egress element spacing [1220.01 ft (371.9 m) vs 1128.23 ft (343.9 m)] - with all

other values in Light-Rail Calc #1 held constant. This is a predictable result because fewer evacuees

correspond to reduced exiting times, and allow wider egress element spacing to achieve the same overall

evacuation time. This parametric analysis was included to show the impact of the passenger/crew load, P t ,

- which affects Equation 1.2 as a function of the egress flow capacity, Q, and the usable width, wc, of the

most constricting element - on the overall result.

RECOMMENDATIONS

The following recommendations are hereby made based upon the development/analyses of Equation 1.2:

• The emergency exit and cross passageway spacing guidelines within the NFPA 130 Standard (2003

edition) should be interpreted as ‘not-to-exceed’ values for rail system applications, and not as constant

design parameters to be uniformly applied to all tunnels regardless of their train length, walkwaywidth, passenger/crew load, fire growth rate, etc.

• The mid-train fire presents an extremely problematic situation for both tunnel emergency egress and

tunnel emergency ventilation - whereas unless emergency ventilation is designed as a ‘point-extract’

system, the emergency egress provisions can be enhanced above those recommended by the NFPA 130

Standard to improve fire-life safety.

• The keys to a mid-train fire response are event recognition and speed of response. Rail system

authorities should have a visual depiction of the entire tunnel network to quickly determine the



location of the incident train, the reported position of the fire with respect to the train length, the tunnel

egress paths and the mechanical ventilation shafts.

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• Equation 1.2 should be used for computing the distance between successive tunnel egress elements for

mid-train fires in rail tunnels. If the result exceeds the NFPA 130 guideline, than NFPA 130’s

maximum cross passageway spacing distance criteria should be observed; if the result is less than the

NFPA 130 guideline, than additional tunnel egress elements should be considered.

• The values utilized in these analyses to represent the egress flow capacity, Q, and the egress travelspeed, V , during tunnel evacuations were taken from the NFPA 130 Standard (2003 edition) guidelines

for station egress planning. Better data is needed to simulate the actual egress flow capacities and

travel speeds during tunnel evacuations.

• Subject to approval by the AHJ, passenger evacuations should be controlled by the rail system

authority via the train crew. The manner in which the controlled evacuation is planned/executed will

have a tangible effect upon the time required to evacuate the train, in general, and on the results of

tunnel egress element spacing calculations using Equation 1.2, in particular.

• The parametric study presented herein showed the results of Equation 1.2-based analyses when six of

the data inputs were altered while the other variables were held constant. More parametric study may

be completed (as needed) by the designers of underground rail systems in order to select the best

possible emergency egress solution for the specific tunnel application.

• If one or more of the active variables in Equation 1.2 are unknown or undeterminable for a particular

rail system application due to information availability, construction sequencing, etc, then the defaultcondition for this particular system application would be to implement the current NFPA 130 design

guidelines for tunnel egress element spacing.

• The determination of whether a particular tunnel egress element is an emergency exit or a cross

passageway should depend upon: emergency response/ingress requirements, the tunnel depth below

the surface, the number of parallel tunnels, rescue train availability, special considerations for disabled

evacuees and the relative safety of any designated refuge areas.

• Tunnel emergency ventilation systems should be designed in accordance with the NFPA 130 Standard,

the ASHRAE HVAC Applications Handbook and the Subway Environmental Design Handbook.

Though related to the manner in which a particular rail system authority deals with a tunnel fire event,

the actual design and operation of the emergency ventilation system is beyond the scope of this paper.

REFERENCES

ASHRAE. 2003. 2003 ASHRAE Handbook - HVAC Applications, Chapter 13. Atlanta: American Societyof Heating, Refrigerating and Air-Conditioning Engineers, Inc.

ASHRAE. 2005. 2005 ASHRAE Handbook - Fundamentals, Chapter 38. Atlanta: American Society of

Heating, Refrigerating and Air-Conditioning Engineers, Inc.

NFPA. 2003. NFPA 130 Standard for Fixed Guideway Transit and Passenger Rail Systems, 2003 edition.

Quincy, Mass.: National Fire Protection Association.





UMTA. 1976. Subway Environmental Design Handbook, Volume 1: Principles and Applications, 2nd

edition. Washington, D.C.: Urban Mass Transportation Administration.

Tunnel Emer Egress & Mid-Train Fire_R3

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