Evaluation of Tunnel Ventilation System at Delhi Underground Metro Station
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Evaluation of Tunnel Ventilation System at
Delhi Underground Metro Station
Vaibhav Joshi, Dr. Dilbag Singh
Department of Instrumentation and Control Engineering,
Dr. B R Ambedkar National Institute of Technology,
Jalandhar, Punjab, India
vaibhav.joshi00@gmail.com, singhd@nitj.ac.in
Abstract: This paper inspects underground complex in nature, such as turbulence, combustion
stations and evaluates the tunnel safety norms and radiation, combustible materials, fire locations, fire
practices followed at the Delhi Metro Rail location, space geometry etc., which affect the fire
Corporation Ltd. (DMRC) by taking into and smoke propagation. The experiments in a scaled
consideration the Subway Simulation System underground station provide useful information.
(SES) and the Tunnel Ventilation System (TVS) However, the practical conditions differ from the
being employed for tunnel operations of the metro experimental conditions and thus these experiments
train. The various modes of tunnel operation have are not sufficient to provide completely robust
been analyzed on the basis of various National Fire management systems.
Protection Association (NFPA) standards. A Park et al. [4] conducted a numerical study to
comparison with other successful mass rapid evaluate fire outbreak in an underground station.
transit systems across the world has also been They took measurements from an actual underground
undertaken. Shortcomings along with station platform for numerical analysis to investigate
corresponding improvements of the existing the ventilation of the station and smoke in case of a
system have been stated and a Mass Rapid Transit fire. The velocity measured at various points was
System (MRTS) has been designed for the city of compared with the results obtained by numerical
Jalandhar which takes into account various analysis.
factors and commuting trends of the city dwellers. For the smoke management system to work more
effectively, a sound foundation design of the subway
Keywords: Tunnel Ventilation System (TVS), has to be laid down. An important factor in advancing
Subway Simulation System (SES), Mass Rapid the design methodology for tunnel ventilation is the
Transit System (MRTS), National Fire Protection tremendous progress in the computer technology
Association (NFPA) applicable to tunnel safety. Faster and more
affordable computers encourage a wider use of design
simulation programs, such as Subway Environment
I. INTRODUCTION Simulation (SES) and Computational Fluid Dynamics
(CFD) to provide quick and inexpensive answers to
There have been some numerous fire incidents in complicated network models of airflows and smoke
underground train stations internationally in the past. control.
The October 25, 1995 city subway fire in the capital This paper explicates the basics of the architecture
city of Baku, Azerbaijan rendered 300 dead and 270 of an underground metro station, states the
wounded. Another fire incident on November 18, rudimentary principle and purpose of the Subway
1987 at the King‟s Cross subway station, London Simulation System (SES) and ascertains the basic
caused by the dropping of a matchstick by a procedure involved in the process. Shortcomings and
passenger. The matchstick dropped into the gears of suggestions regarding the tunnel safety system at the
the escalators and ignited the oils and some Delhi metro rail Corporation Ltd. have been put
inflammable toxic material. The incident left 31 dead forward in comparison with other underground metro
and 27 wounded. The February 18, 2003 arson fire rail systems around the world. An elementary mass
[1] at the subway in the Daegu city of South Korea rapid transit system (MRTS) has also been proposed
caused nearly 200 deaths. The heavy casualties of for the city of Jalandhar, India.
these incidents were mainly due to the smoke and the
failure of the smoke management systems.
The above data shows that effective smoke II. BASIC ARCHITECTURE
management is of utmost importance. The smoke in a
fire generally lowers the visibility and causes slower The basic architecture of an underground DMRC
evacuation. Moreover, the toxic gases released due to station has three levels, the ground level, the
incomplete combustion cause fatality in a short concourse and the platform or subway level as shown
duration of time [2], [3]. In general, fires are very in figure 1.FPS system for e.g. aerodynamic model of the
corridor, node diagrams and node sections. After this
the derived parameters from the data collected are
determined. These include train route modeling,
ventilation plan arrangements.
3) SES Inputs: The various data required for
designing are procured form surveys and forecasts
using statistical measures. These include weather
data, track-way ventilation system, fan data, route
data. Besides this train schedule and train data is
obtained from the O&M department.
4) SES Outputs: The output parameters of the SES
Figure 1: Basic architecture act as the governing principles for the design of the
underground station. These parameters include
The ground level consists of the entry/exit arena airflow rate, temperature, humidity, pressure,
connected to the surface roads. The concourse cooling/heating requirements, air velocity and energy
comprises of the main public hub, ticket counter, consumption. An updated train status informing about
plant rooms and the Station Control Room (SCR). the location and speed is also paramount to subway
The platform is the location for boarding on or off the designing.
train.
The concourse is air conditioned using the
Environmental Control System (ECS) but the IV. TUNNEL VENTILATION SYSTEM
platform and the tunnel region experience the most
extreme conditions of heat and humidity and are most At DMRC, the Tunnel Ventilation System (TVS) is
vulnerable to fire outbreaks. designed according to the output of the Subway
Environment Simulation (SES). The design weather
data from the ASHRAE handbooks [6] has been used
III. SUBWAY ENVIRONMENT SIMULATION to arrive at the design criteria. The TVS is used for
The Subway Environment Simulation (SES) system is maintaining a workable environment in the tunnels
a computer designer- oriented tool which provides during the expected range of operating conditions. It
estimates of airflows, temperatures and humidity provides ventilation and air movement control over
levels as well as air conditioning requirements for the tunnel area and track-way adjacent to each station
both operating and multiple track subway systems. meant for train locomotion.
This simulation tool was developed by Parsons TVS has been designed to fulfill two prime
Brinckerhoff [5] in 1975 and has been employed ay purposes:
DMRC for various applications. It approximates the 1. An effective means of controlling smoke flows
ventilation system capacity to control the spread of during emergency conditions (such that both patrons
smoke, thus enabling the designer to design the TVS and employees can evacuate safely and also, the fire
system accordingly. fighting personnel can reach an incident location
It provides the most effective size, configuration, without traversing a smoke filled path).
spacing and location for ventilation and fan shafts. A 2. An acceptable environment in the tunnel and
forecast of the impact vehicle air conditioning on station track-way conducive to the operation of Delhi
overall heat rejection, temperature and humidity in Metro trains.
the system is furnished. It takes into account 3. A safe environment for the passengers as well as
operating schedules headways, vehicle speeds and the employees to operate at the platform and track-
train sizes and provides inputs on power demand, air way.
velocities and pressure transients crucial to a subway A. System Architecture
designer. Other factors are also taken into
The TVS consists of two reversible Tunnel
consideration for e.g. effect of track vertical
Ventilation Fans (TVF) located at each of the north
alignment and variations due to heat sink.
and south end tunnel ventilation plant rooms. These
The procedure for carrying out SES may be divided
fans operate to provide forced ventilation in the
into several steps:
tunnels during the congestion and emergency modes.
1) Collection and Study of Data: It includes For each of the tunnel ventilation fans, corresponding
architectural plans, alignment sections, weather data, Tunnel Ventilation Dampers (TVD) are installed for
geo technical data, passenger forecast data for the controlling the air flow as required. Fixed eversible
station and the rolling stock data and train operation Tunnel booster Fans (TBF) and supply nozzles
plan. This data is procured from different surveys and maintain the required thrust in the tunnel. All the
forecasts using statistical measures. Reversible fans are capable of accepting a direction
2) Inputting the Data: SES is based on the FPS reversal command without any time delay.
system all the available data has to be converted inB. Modes of Operation operate in operate only in supply mode up-line and
There are four modes of operation that were down-line.
manually created to suite different conditions [7]. In the emergency mode, an area of the tunnel is
Each mode has a corresponding manner in which the under fire or contains smoke. Emergency conditions
components operate. are the TVS operational modes for any variety of
The four modes of operation are: occurrences including transit vehicle malfunctions,
derailment or fire that may result in smoke conditions
1) Normal: the operation of station and tunnel is
in the tunnel. The TVS of one of the station acts in a
going as expected and the TVS is not engaged.
supply mode and that of the other station acts in an
2) Congestion: Meant for situations like natural extract mode depending upon the location of the fire
disaster in which people tend to seek shelter in the and the direction of safe passage for the passengers as
station and there is an uncertain situation. shown in figure 3.
3) Emergency: Meant for the extreme situations
like fire and flooding etc.
4) Maintenance: This mode is activated mostly at
night but may be used if maintenance is required
even during the day time in some urgent
circumstances.
In the congestion mode, the train has stopped in the
tunnel beyond a predetermined time period and this
causes the tunnel temperature to rise [8].
Consequently, it prevents the train air conditioning
from working properly. To assist the operator, the
tunnel temperatures in each section are monitored by
a temperature sensor (one located on each track in a Figure 3: Tunnel ventilation Fans (TVF) in emergency mode
tunnel) and sent to the relevant Station Control Room
(SCR) and the operational Control Center (OCC). The
TVS system then follows the command from the
control center. V. DESIGN PRACTISES AND EXAMPLES
ABROAD
A. London Underground Rail System
Colloquially referred to as ‘The Tube’, it is the
world‟s oldest underground rail system consisting of
270 stations and around 400 kilometers of track,
making it the second longest metro system in the
world by route length after the Shanghai Metro. Lines
on the Underground can be classified into two types:
subsurface lines and deep-level lines [9]. The
subsurface lines, which were dug by the cut-and-
cover method while the deep-level or tube lines,
Figure 2: Track-way Exhaust Fan system which were bored using a tunneling shield.
The Tube has no provision of air conditioning;
In the event of Congestion, to prevent the however the new S-stock trains however will have air
accumulation of warm tunnel air around idling train conditioning system for providing a comfortable
leads to activation of TVF push – pull mode as shown environment for commuting. In summer,
in figure 2. The nearest station acts in supply mode temperatures on parts of the Underground can
and farthest station acts in extract mode. The TVS become very uncomfortable due to its deep and
can operate in various modes as listed below: poorly ventilated tube tunnels. Posters may be
observed on the Underground network advising
1) Open mode: The track-way exhaust fans can passengers to carry a bottle of water to help keep cool
operate in both the directions i.e. to supply or to without the air conditioning. Each line is being
extract air. The supply or extraction process can be upgraded to improve capacity and reliability, with
executed both up-line and down-line. The tunnel new computerized signaling, automatic train
ventilation fans in extract direction can operate only operation (ATO), track replacement and station
in open mode i.e. discharge to atmosphere. refurbishment, and, wherever needed, new rolling
2) Close mode: The track-way exhaust fans can stock.B. Taipei Railway Underground Project fire the OTE would clear the smoke from the tunnel
space, although smoke would inevitably enter the
The Taipei Railway underground project
platform areas through the open train and the platform
undertaken in the capital city of Taiwan consists of a
edge doors. To ensure tenable conditions, the
tunnel with length of 22.5 kilometers, including five
mechanical smoke exhaust system located on the
underground stations and three emergency stops. The
platform would start operating. For designing of the
emergency procedure design concept, in adapting the
smoke control system, Computational Fluid
NFPA 130 [10] as a design guide, is to provide a
Dynamics (CFD) [13] smoke modeling has been
smoke-free escape route should a fire occur in the
carried out using Fire Dynamics Simulator software.
tunnel or on the underground platform. The ceiling
The station design includes twin-bore tunnels
plenum has been adopted as smoke reservoir to
throughout the line with crossovers between the two
alleviate the smoke descending rate, and thus
bores at three locations along the tunnel. At these
facilitate more time for evacuation [11]. The
locations the TVS is designed to reduce smoke spread
evacuation system lacks a stairwell pressurization
between the two bores for all fire scenarios near the
system for handicapped patrons. The tunnel
crossover. The CFD analysis demonstrated that in all
ventilation fans, when operated on an emergency
fire scenarios near the crossover sections, smoke
mode, introduce an upwind along the stairwell so that
spread would be reduced in the non-incident tunnel.
evacuees can run upstairs under tenable conditions.
The emergency operation mode has been developed
innovatively to improve ventilation system VI. SUGGESTIONS AND IMPROVEMENTS
performances. The design concept is to operate the
system on an “Exhaust Only” mode for the first six The practice of halting trains in the tunnel during
minutes to comply with the NFPA 130 [10], for a safe congestion at DMRC places a lot of burden on the
evacuation of the passengers. It is then followed by an TVF system and also causes passenger
unbalanced push-pull mode to provide a smoke- free inconvenience. Trains halted in the tunnel run the risk
entry point for the firefighters through the primary of having their air-conditioning units unload as
and tertiary staircases. For the evacuation process, the dwelling trains cause the temperatures in the tunnel to
system considers factors like bottlenecks, pushing and rise. Also, for the purpose of conceptual design, the
taking over while calculating the total evacuation fan sizing is based on the logical course of only one
time needed for reaching from the farthest exit point train being permitted in the ventilation zone. If more
or for passing through the exit points [12]. The smoke than one train is to be allowed, added heat and
diction, humane confirmation and announcement of increased ventilation equipment are to be considered.
fire, each step takes time to complete, which add up During an incident of vehicular congestion, the Train
to around four minutes for all the passengers to leave Service Regulator should halt as many subsequent
the platform and six minutes to leave the station, thus DMR trains as possible at the station itself. This
complying with the NFPA 130 criteria [10]. The would place lesser burden on the TVF and allow the
Taipei Railway under ground project has been in passengers to alight to subsequent trains into the
operation since 1999 and has a satisfactory safety station.
record. Currently the DMR Tunnel Ventilation System is
using the closed system concept and the open system
C. Sydney Metro Project concept. The open system requires the sir-
conditioning to use 100% outside whereas in the
The project had been undertaken to design a new closed system the station air is re-circulated to the
underground line through Sydney‟s central business station air-conditioning system. The Platform Screen
district consisting of seven underground stations via Doors (PSD) concept which is not being employed
seven kilometers of tunnels. The stations have been may also be incorporated in the designing of future
designed following the guidelines of NFPA 130, 2010 underground metro systems. Platform screen doors
[10] and Building Control of Australia (BCA) so that are actually solid, transparent barriers that are aligned
evacuation off the platform would be possible in four with the vehicle doors such that the passenger
minutes. The evacuation modeling has been carried entry/exit to the DMR trains is automated. The PSD
out using SIMULEX modeling software which takes system has the inherent ability to isolate the air-
into account the variations in human size, mobility conditioning from the hot & humid air in the tunnels
and movement speeds apart from other factors. and also partially prevent the smoke and toxic gases
According to the concept design for the smoke from entering the platform in emergency and
control systems throughout tunnels to separate the congested conditions. They also provide the least
two areas with platform edge doors and provide operating cost for the environment control systems.
separate smoke control systems in both areas. The On the site, another improvement may be to set up
tunnels have a longitudinal ventilation system the tunnel at the top of exhaust pipe while the
controlled from fans located at either end of the ventilation system and smoke extraction system be set
station which also provides an Over Track-way up separately using vertical exhaust to replace the
Exhaust (OTE) system above the tracks. In case of a horizontal direction of the smoke method.VI. PROPOSED MASS TRANSIT SYSTEM FOR platform at the second basement. The central portion
JALANDHAR of the concourse would serve as the ticketing hall
where ticket machines, automatic machine gates,
Owing to the success of the Delhi mass rapid transit station control room are located. Equipment rooms
system, a system similar in structure is proposed for serving the operations of the station would be located
the city of Jalandhar with the exception of the whole on both ends of the station. Where possible, small
system being underground. The Jalandhar metro shops, Automatic Teller Machines (ATM), public
system would provide an efficient and effective land telephones etc. would be provided. The platform
transport network that is integrated, efficient, cost- would approximately be the length of the rolling
effective and sustainable to meet the needs of the stock used in the system and separated from the
growing urban population. This paper proposes only tracks by the platform screen doors (PSD) thus
two initial routes and a single central station which adopting the PSD concept. The platform beneath the
may be extended during further stages of planning. concourse would basically be an open area for the
The basic design has been inspired by the Delhi metro waiting/boarding passengers. The platform and
system while the inspiration for the fire safety concourse levels are linked by open staircases and
systems and parameters comes from the Beijing Mass escalators at the public areas. Enclosed staircases at
Rapid Transport System (MRTS). both ends would be provided to cater quick egress
from the station in the event of an emergency.
A. Basic Route Planning
Since the layout of the city is longitudinal, two C. Fire Safety and Egress
main corridors, North-South and East-West would be Conforming to the requirements of the NFPA 130
the institutional routes. „Jyoti Chowk‟ near the central [10], the underground station would be of non-
town would be the atrium of the corridors. The north- combustible construction built to a fire resistance
south corridor would be collateral to the railway line, period of four hours. In addition to the open staircases
running beneath the Grand Trunk (G.T.) road, thus and escalators, enclosed staircases would be provided
connecting the northern outskirts to the centre of the at each end of the station as a secondary means of
city and up to the Inter State Bus Stand (I.S.B.T) egress. The fair gates installed would be fully open in
providing service along with the existing bus and auto the event of an emergency. Escalators would be
service. The east-west corridor would connect the stopped in an emergency. The passengers would be
western regions of „Model town‟ with the railway able to leave the station within 4 minutes, a time
station and terminating at the IOCL colony as shown frame set by the NFPA 130 [10]. Exit signs and exit
in figure 4. The Jalandhar metro would provide direction lights would also be provided to identify the
service in neighborhoods where only the auto service exit routes.
exists as well as complementing the bus service on
other, more popular routes. Feeder auto service may
D. Fire Detection and Protection
also be provided for connecting the nearby areas to a
metro station. The Jalandhar MRT system would comply with the
standards set by the NFPA 130 [10]. Each station
would be provided with automatic fire sprinkler,
automatic fire alarm system, total flooding gas fire
suppression system, fire hose reel system and portable
fire extinguisher. Voice communication systems
would also be provided for necessary communication
during an emergency.
D. Smoke Control System
The smoke control system designed for the track-
way (outside the platform screen doors) would consist
of tunnel ventilation fans (TVF) at both ends of the
station and under platform exhausts (UPE) and over
track-way exhausts (OTE) as shown in figure 5. The
combined exhaust capacities would exceed the smoke
generation rate to provide effective smoke extraction
Fig 4: Proposed Jalandhar metro route map. Blue line indicates the while make-up air is being induced through the
route of the train. Red dot is the central atrium. staircase. The tunnel would be set up at the top of
exhaust pipe while the ventilation system and smoke
B. Basic Station Layout extraction system would be set up separately using
The NFPA 130 [10] is to be adopted as the base vertical exhaust to replace the horizontal direction of
design guide. A typical underground station would the smoke method. This would provide improved
consist of concourse level at the first basement and a smoke control. Operation of the emergency tunnelventilation system would be initiated from the [6] ASHRAE Handbook – HVAC Applications, Chapter 13 –
Operational Control Centre (OCC). Local controls Enclosed Vehicular Facilities.
[7] Contract Manual – MC1A – Section B – Outline Design
would be permitted to override the OCC in all modes Criterion – Building Services. Delhi Metro Rail Corporation
if the OCC becomes inoperative at any point of time. Ltd.
[8] Contract MC1A – Vishwavidayalaya to Kasmere Gate
B & M Manual – Electrical & Mechanical Services. Delhi
Metro Rail Corporation Ltd.
[9] Paul C. Miclea, Evolution of tunnel Ventilation and Safety
Criteria in a Changing City Environment.
[10] NFPA 130, 1995. U.S. National Fire Protection Association‟s
Standard for Fixed Guideway Transit and Passenger Rail
Systems.
[11] Dr. K.H. Yang, T.C. Yeh. Experimental Validation of the
Taipei Underground Railway System under Emergency
Operation Modes.
[12] Chi-Ji Lin, Yew Khoy Chuah; Smoke Management and
Fig 5: The system would consist of four ducts above the tracks and Computer Simulation of an Underground Mass Transit
a false ceiling above the platform. Station in Taiwan.
[13] Nuri Yucel, Muhammed Ilter Berberoglu, Salih Karaaslan,
Nureddin Dinler, Experimental and Numerical Simulation of
CONCLUSION Fire in a Scaled Underground Station. World Academy of
Science, Engineering and Technology.
This paper started with a critique about the
overwhelming research efforts put into establishing a
tunnel ventilation system at the Delhi Metro Rail
Corporation Ltd., discussing the subway environment
simulation system which acts as an analysis system,
briefly addressing the shortcomings of the existing
arrangement and suggesting some improvements
therein. The existing tunnel safety system currently
being employed at the Delhi Metro Rail underground
stations was found to be efficient, effective and robust
enough to be able to adapt to extreme conditions thus
maintaining a clean satisfactory record so far without
any accidents so far.
Some designs and approaches adopted by
successful underground rail systems across the globe
have been analyzed on the basis of which an
elementary mass rapid transit system was designed
for the city of Jalandhar, India. This underground
metro system would cover parts of the city currently
untouched by the bus service while assisting the bus
service in other heavily populated areas thus helping
to cope up with the growing population of the city.
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[4] W.H. Park, D.H. Kim, H.C. Chang, “Numerical Predictions
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[5] Parsons Brinckerhoff Quade and Douglas, (1980). Subway
Environment Design Handbook.B. Beijing Mass Rapid Transit System
Beijing has eight operational subway lines. Smoke
exhaust and emergency ventilation systems are
provided for underground stations and tunnel. Due to
the space limitations, the normal ventilation and air-
conditioning systems are integrated with the smoke
control system. However, normal ventilation mode
can be shifted to emergency mode immediately once
a fire is detected.
COLLECTION
INPUTTING
AND STUDY OF
THE DATA
DATA
SES OUTPUTS SES INPUTS
Figure 2: Procedure for carrying out SESYou can also read
