8. Equipment and Systems

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ROAD TUNNELS MANUAL

8. EQUIPMENT AND SYSTEMS

All rights reserved. World Road Association (PIARC)


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PIARC ROAD TUNNELS MANUAL PIARC

8. Equipment and systems

If tunnels are longer than a few hundred metres, specific equipment is required to enhance safety to theusers, both in normal situations and in case of accidents.

To reduce the risks of accidents and limit the possible consequences, but also to keep an adequatelevel of comfort to the users, a large variety of equipment can be installed. Chapter 7 of the report05.06.B "Reduction of operating costs of road tunnels" discusses road tunnel equipment andChapter 3of the report 2008R15 "Urban road tunnels" provides details for the design and refurbishment ofequipment.

A significant amount of electric power is required to feed the equipment installed in the tunnel. Theelectrical power supply systems (Section 8.1) must provide enough power in the case of normal andemergency conditions. This also means that the system must work even in the case of blackouts, inorder to feed at least the equipment which is absolutely necessary. The status of this equipment shouldalso be monitored. For this reason, a SCADA system (Section 8.2) may be implemented.

A first type of equipment is the communication and alert systems (Section 8.3). This includes systems

used to check periodically the conditions in the tunnel and also to make the operator aware of apossible danger or an accident. Together with systems for surveillance and control of traffic (Section8.8), some detection systems can be installed. These include automatic incident detection andsmoke/fire detection. This information may also come directly from people involved, through alarmpush button or emergency telephones. The latter also allows a communication between people in thetunnel and control personnel. This is useful for the control personnel to have additional informationwith respect to locations, status of people, etc. but also to supply information to people in the tunnel.

This kind of equipment also includes systems used to alert the users in the tunnel or to coordinate theintervention. Loudspeakers and radio-retransmission of public FM broadcasts, frequencies of operatorsand emergency services can be used for these purposes.

To guarantee comfort to the users and reduce the risks of accident it is important to obtain adequate

visibility and reduced concentration of contaminants. For these purposes, an adequate lighting system(Section 8.4) and ventilation system (Section 8.5) are necessary. Ventilation is also crucial in the caseof emergency conditions, as it affects both the fire development and smoke propagation. Depending onthe traffic and the tunnel length the ventilation can be only natural, only mechanical or mixednatural/mechanical (i.e. natural in ordinary conditions and mechanical in emergency conditions). Anadditional element to manage risk is signalling (Section 8.9). This is important in order to highlightpossible obstacles or danger, but also to help finding the emergency exits, alarm pushbutton,extinguishers, etc.

In the case of accidents, equipment is required to extinguish fire. This includes fire-fighting equipmentavailable in the tunnel to the users and the emergency teams (Section 8.6) and fixed fire fightingsystems (Section 8.7), which automatically intervene. In these conditions, barriers (Section 8.10) areimportant to prevent users outside the tunnel at the time of accident from entering the tunnel.

Contributors

This Chapter was written by Working Group 1 and Working Group 4 of the C4 committee (2008-2011) in which:

Antonio Valente(Italy) coordinated the workJ ean-Claude Martin (France) authored Sections 8.0, 8.1 and 8.2Arthur Kabuya(WG4 : Belgium) andJ ean-Claude Martin (France) authored Section

8.3 excepts Sections 8.3.4. Automatic incident detection and 8.3.5. Fire/smoke detection :Purpose of fire and smoke detection that were authored byArthur Kabuya (WG4 : Belgium)

J ean-Claude MARTIN (France) authored Section 8.4

Antoine Mos(WG4 : France) authored section 8.5 VentilationArt Bendelius(WG4 : USA), authored Section 8.6 Fire fighting equipment

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Arnold Dix (WG4 : Australia) andFathi Tarada(WG4 : UK) authored Section 8.7 Fixed firefighting systems

J ean-Claude MARTIN (France) authored Sections 8.8, 8.9 and 8.10Fathi Tarada (UK) and Ignacio del Rey (Spain) coordinated and reviewed the WG4 inputsJ ean-Claude MARTIN (France) coordinated and reviewed the WG1 inputsFathi Tarada (UK) reviewed the EN version.


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8.1. Electrical power supply

Most of the tunnel equipment and systems requires electrical energy to operate. Therefore, equipmentfor supplying power to the tunnel must be installed. This installation has to satisfy two essentialrequirements:

Supply safe and sufficient power to allow all the equipment to operateMeet the needs under all operational situations (normal, degraded, critical).

The power required for supplying a tunnel is directly related to the nature and number of equipmentinstalled in it. Depending on the amount of electrical energy required (kWh), power may be suppliedin low voltage or high voltage.

Each country has its own regulatory requirements with regard to tunnels and a specific structure interms of distribution networks: therefore, the architectures retained may be significantly different intunnels with similar characteristics. However, some identical principles can be noted, such as:

The presence of a standby power supply (double supply, diesel generator, etc.),The installation of a device allowing remedying a total loss of power supply. This system

(uninterruptible power supply (UPS), diesel generator...) supplies electricity to equipment

critical for safety, during a limited period of time.

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8.2. Supervisory Control And Data Acquisition systems (SCADA)

In a road tunnel, the equipment plays a vital role for the safety users. The operator therefore has tomonitor such equipment continuously for determining their status (working or fault) and/or theiroperating mode (automatic, manual or stopped).

Many devices are servo-controlled by sensors and operate automatically (lighting, ventilation...)according to pre-determined thresholds. Others are activated or deactivated depending on the operatingconditions. It is thus useful for the operator to be able to remote control them (signalling, variablemessage signs, barriers, ventilation, lighting, pumps ...).

Lastly, since the equipment may be operated very differently (continuous, occasional, or very rare), itis necessary for the operator to have information on the operational duration (hour used) for each ofthem.

These functions of surveillance, control-command and data archiving are very often performed by asingle system: the Supervisory Control And Data Acquisition system (SCADA).

Several SCADA systems are available worldwide and their performance is being improved constantly.The systems installed in road tunnels of comparable characteristics are therefore rarely completelyidentical, even for the tunnels of the same operator. Even so, the architectures follow certain rules thatare widely prevalent:

Collection of information via networks in loop Intelligence (programmable logic control notably) installed near the equipment Separation of networks: acquisition, transport and supervision Redundancy of certain sub-assemblies for improving their dependability.

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8.3. Communication and alert systems

It is important for the operator to be able to communicate with the user. It should be possible for thiscommunication to take place in both directions - operator to user and user to operator. Theseexchanges should be possible in all operational situations: normal, degraded or critical.

Several devices allow ensuring this communication function (the alert is considered as a particularform of communication). They do not all offer the same functionalities: some of them allowestablishing a transmission from user to operator (alarm pushbuttons, automatic alarm while usingcertain evacuation systems ...) while others allow a transmission from operator to user (messagesbroadcast on FM frequencies, loudspeakers). Only one of them allows a full exchange (emergencytelephones).

8.3.1. Emergency telephones

Emergency telephones allow a user, victim of an accident in tunnel, to contact the control-commandcentre in charge of the tunnel. In addition to establishing a voice link, the use of an emergencytelephone by a user also gives his precise location.

These emergency telephones are installed at fixed intervals on boxes or in emergency stations ofdifferent types. The distance between two emergency telephones is often specified by regulations andtherefore varies from one country to another.

The structure of this device is quite simple. The emergency telephones in the tunnel are connected to acentre that receives the calls made from the tunnel. Usually, this centre is located in the control-command centre of the tunnel and sometimes in the premises of police services under whose

jurisdiction the tunnel is placed.

8.3.2. Alarm pushbuttonsAlarm pushbuttons allow a user to send an alarm to the control-command centre in case of accident intunnel. Being not very expensive equipment, it can be installed at frequent intervals.

This device is not much used because to a certain extent, it duplicates the emergency telephone andmoreover, it does not allow a two-way communication between the user and the control-commandcentre.

8.3.3. Automatic alarm when emergency systems meant for users are used

As mentioned above, the user has access to several devices that he can use in tunnel, particularly inemergencies: emergency telephones and sometimes alarm pushbuttons. He also has fire extinguishers

and, in most tunnels, emergency exits.

It is essential for the operator to be informed as early as possible when a user operates one of thesedevices, in order to take adequate actions. This is not difficult when emergency telephone and thealarm pushbuttons are installed because, very often, the control-command centre receives the call orthe alarm information. When the emergency telephones are terminated in a place other than thecontrol-command centre, procedures have to be set up so that the service receiving the call informs thecontrol-command centre at once.

In the case of extinguishers and emergency exits, sensors are very often installed for detecting achange of status and communicating this information to the control-command centre by using theSCADA system. The operator is then informed that a user in tunnel is requesting assistance.

For the fire extinguishers, the information taken into account is often the action of removing theequipment from its support or opening the door in the emergency station etc. For the exits, the

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information taken into account may be the opening of the door or the detection of a presence in theexit or both of these.

8.3.4. Automatic incident detection

When a tunnel is equipped with a video-surveillance system (refer Section 8.8), the images comingfrom the tunnel and its vicinity are shown by displays installed in the control-command centre. It isdifficult for the operator to monitor more than a few displays simultaneously with a constant alertnessduring several hours.

For remedying this difficulty, operators are increasingly using automatic systems for detecting anincident. In certain countries, the use of such equipment is even obligatory for specific tunnels.

Type and Function of Automatic Incident Detection

Automatic incident detection (AID) is normally based on computer-based analysis of video imagestreams generated from cameras set up to view tunnel traffic. A number of algorithms are availablewhich can detect a range of incidents, including:

stopped vehiclesvehicles moving in the wrong directionspeed dropslow vehiclepedestriansdebris in road tunnelsmoke flamesentry into restricted zones

Since serious vehicle fires normally develop after traffic has stopped (e.g. following an accident), itfollows that a'stopped vehicle' alarm from an AID system can be expected to precede alarms triggered

by other systems, such as temperature and smoke detectors. This early warning provided by AIDallows time for tunnel operators to confirm the nature and location of the incident, and to alloweffective intervention., This may be through the choice of an optimal choice of ventilationconfiguration, prevention of secondary accidents through operational measures, rapid warning tomotorists upstream of the incident. It also gives opportunity to call the emergency services, closing ofaccess, messages on variable message signs and on the radio, call to breakdown lorry, advice to exitthe tunnel, etc.

Video smoke detection systems are described in Section 6.3.3 "Currently Used Methods" of report05.16.B 2006.

Video-based AID systems can provide real-time information on the traffic flow, volume and speed.They can record pictures at the origin of the incident and can interact with other systems such as theSupervisory Control and Data Acquisition (SCADA) system. Video-based AID systems normallyinclude cameras, a video image processing system processing images from one or several cameras,Internet Protocol (IP) video encoders and decoders on IP to return images to monitors or computerdisplays. Furthermore a video management system composed of one or two redundant serversproviding video and othersfunctions (recording of video mass and AID incident, collecting and storingreal-time traffic data and traffic events, interfacing with the tunnel SCADA system), networkequipment and communications lines(optical fibres, coaxial and Unshielded Twisted Pair cables).

Design and Commissioning of AID Systems

The design ofAID systems in tunnels should be undertaken with due account of the following issues:

Choice of incidents to be detectedDetection accuracy (i.e. minimisation'false negatives' in detection incidents)Minimisation of false alarms (i.e. minimisation of'false positives')

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Location of existing cameras in the tunnelGeometric features of the tunnelAccess for maintenance staffBright sunlight'bleaching' near portalsSunlight movements in the vicinity of portalsChanges caused by the passage of vehicles in the tunnel (lights, occlusion by high vehicles)Change of lighting regime in the tunnel (lighting on/off)Reflections in the tunnel In case of an AID system integrating IP video stream, the capacity of the existing IP network

should be checked to ensure there is sufficient bandwidth available

The 2009 Routes/Roads article "Fire Detection Systems in Road Tunnels - Lessons Learnt from theInternational Research Project" concluded that "to deal with obstructions, most manufacturers of fieldof view detectors recommend two detectors covering the same area from different angles, such as fromboth directions within a tunnel". Multiple cameras may also be required for redundancy purposes, incase of camera failure. Typically, the camera fields of view are designed to overlap, such that failureof any one camera can be compensated through the images from neighbouring cameras.

Section IV.2.1. "Traffic Incident Detection Devices" of report 05.15.B 2004 suggests that cameralocations can vary from 30 to 150 meters if they are used for automatic incident detection.

The performance of an AID system performance depends to a great extent on successfulcommissioning and calibration, prior to deployment. Experience from tunnel installations indicatesthat such commissioning and calibration can take several months to undertake.

8.3.5. Fire/smoke detection : Purpose of fire and smoke detection

Fire and smoke detectors are always an integral part of a control loop which is set up by sensors, alarmtriggering equipment, transmission cabling, evaluation units, etc., and which taken together aregenerally referred to as a fire alarm system.

Fire and smoke alarm systems in road tunnels are designed to detect fires and smoke production as fastas possible so that safety equipment and procedures can be activated without delay. Their mainobjectives should be:

informing tunnel users at the earliest opportunity so to enable them to organize their self-evacuation and self-rescuing;

passing on all the possible fire parameters to the operational tunnel staff in order to enable themto change ongoing tunnel operations (traffic control and ventilation systems) according to theemergency procedures (so-called fire mode), and to call in the rescue services, medical staff, firebrigade, police, etc.

to identify the locations of the fire or incident, in order to direct rescue service resources to theappropriate places to assist motorists, for example.

Principles of fire detection

Basically, the fire detection principles are based on the perceived parameters determined by the firei.e. heat, smoke, radiation and production of typical chemical substances. Therefore, the fire detectingsensors can be classified as :

Heat detectors : all material the characteristics of which are sensitive to an increase of heatenergy whenever this implies a temperature rise. Examples are sensors which measuretemperature differences with a reference temperature or rate of temperature rise, glass-fibrecables where its light transmission characteristics are a function of temperature, linear sensorcable with built in electronic circuit, etc.;

Flame detectors based on their sensitivity of infrared and/or ultraviolet wavelength spectrum;Smoke detectors which measure the extinction of a infrared light beam through CO and CO2

ionisation areas;

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Detectors which combine different types of sensors.Each of these detectors has their own specific application domain, related to its response time,robustness, reliability, etc.

Recently video AID systems have proven to be very efficient and fast in detecting fires. In fact, theydetect incident any object or vehicle which does not conform to the normal expected traffic stream.

The cameras can be automatically turned towards the incident scene, which enables the operator todiscover the very early start of a fire.

Fire/smoke detection systems are described inSection 6.3 "Fire detection" of the report 2006 05.16.B.

Requirements for Fire detection system

In a general way, fire detectors in road tunnels must be designed to withstand the followingenvironmental conditions: air velocities up to 10 m/s, reduced visibility resulting from diesel exhaustfumes and abrasive wear stemming from tires and the road surface, increased and short-termfluctuating concentrations of pollutants (carbon monoxide (CO), carbon dioxide (CO2), nitrogenoxides and hydrocarbons), changing headlight intensities, engine heat and hot fumes vehicle exhaustgases, electromagnetic interferences, mixed vehicular traffic (i.e., cars, small lorries, heavy loadlorries, buses and tankers) that will result in varying degrees of tunnel cross section obstruction.

It cannot be stressed enough that they must have a high degree of fail-safe operation and be able tolocate the fire as close as possible. It is advisable that the systems of fire detection possess certainlevel of intelligence to avoid false alarms, because false alarms could entail significant expense torectify and even worse, may discourage the operators after a while run from paying attention to thealarms.

Furthermore, it is imperative that the fire detection/alarm installation is reasonably priced, has lowoperating costs and simple to maintain: referSection 6.3 "Fire detection" of the report 2006 05.16.B.

Parameters dictated by Codes and Standards

The following parameters for automatic fire detectors are specified in national and international codesand standards : maximum time for a fire to be detected, determination of the fire site location,minimum fire load to be detected, approved detection methods, assembly points for fire alarms, detailspertaining to which tunnels should be provided with automatic fire alarm installations (e.g. length oftunnel, tunnels with mechanical ventilation, tunnels that are not permanently monitored by personnel,short tunnels with particularly high traffic densities).

A list of detailed reference material regarding fire detector parameters are described in codes and canbe found inSection 10 "References" of the report 2006 05.16.B.

Fire/smoke detectors currently in use

The efficiency of fire detection is not only based on the type of devices (temperature, light beam

extinction, ionisation, etc.), but also on the detection strategy which and been developed, whichincludes the number of sensors and their level of surveillance in the tunnel.

Automatic incidents detection, analysis of video images including AID systems, closed-circuittelevision (CCTV) observation, equipment such as fire extinguishers which activate alarms by theremoval, as well as the emergency telephones are generally good means to raise an alarm.

Many detectors in use are based on heat and on the rate of temperature rise. When well calibrated, thistype of system generates only few false alarms, but may have a slow reaction rate. Detectors based onsmoke obscuration give early signals but have suffer more false alarms because of smoke exhaustfrom diesel vehicles: refer to Section VI.3.1 "Fire detection" of report 05.05.B 1999.

The 2009 Routes/Roads article "Fire Detection Systems in Road Tunnels - Lessons Learnt from the

International Research Project" deals with fire/smoke systems of road tunnels such as linear detectionof the heat, optical detection of flames, detection by video imaging, punctual detection of heat and

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smoke detection by air sampling system. It concludes that the system of air sampling gives a goodperformance in terms of response time and ability to accurately locate and monitor a fire and the effecton road environment, when taking into account overall performance including false alarms,maintenance and fire detection. The information from this study can be used to determine the mostappropriate technology for tunnel fire detection.

8.3.6. Radio-retransmission of public FM broadcasts, frequencies of operators andemergency services

A tunnel is a closed and confined space that very often does not allow the propagation of radio wavesfrom broadcasters outside the tunnel. For re-establishing this propagation, it is necessary to install theequipment that allows the retransmission of the needed frequencies. Several types of services can beretransmitted:

Rescue services (fire brigade, police...)Operator (patrols, maintenance crews, taxis, bus companies ...)Public FM broadcastsPublic DAB broadcasts (Digital Audio Broadcasting)Cell phones.

There are a very large number of services whose frequencies can be retransmitted but they are not allof them covered, because of problems of cost, not to mention feasibility. As a general rule, one canfind certain frequencies used by the rescue services, frequencies used by the operator, a few FM and orDAB frequencies and frequencies of cell phone operators.

When one or more Radio frequencies are retransmitted, a device is installed that allows inserting pre-recorded messages. In case of need, these radio broadcasters are interrupted and messages regardingthe tunnel are broadcasted for the attention of users, in order to give them indications regarding thesteps the operator wants them to follow.

A radio-retransmission installation in tunnel is essentially composed of:

An antennaA transmission/reception unit that allows transmitting from the outside into the tunnels technical

room that needs to be cooled.A transmission/reception unit that allows transmitting from the tunnel to the outside (not for

public broadcasters but for emergency services etc.)A radiating unit in tunnel (radiating cables or antennas).

8.3.7. Loudspeakers

There are not many devices that allow addressing the user directly for giving information or asking thetunnel users to behave in a particular manner. For solving this problem, some tunnels are equippedwith loudspeakers. In practice, depending on how they are used, the loudspeakers offer differentfunctionalities. The following points can be mentioned in particular:

Loudspeakers installed at fixed intervals in the tunnel, to give information and instructions tousers whose vehicle has stopped inside the tunnel

Loudspeakers (or sirens) installed at fixed intervals inside the tunnel that emit a sound signalindicating a danger

Loudspeakers (or sound beacons) installed near emergency exits that providing information tousers about to use an exit and where it is located.

These devices are not however widely used at present. Their use must be studied for each case andoften, they are suited for very specific tunnels (very dense traffic, length, etc.).


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8.4. L ighting

In the majority of tunnels the natural penetration of light does not allow satisfactory conditions ofvisibility for the users. It is therefore necessary to install artificial lighting offering satisfactoryconditions of visibility and comfort to the users.

In terms of functionalities, the lighting installation must allow for:

A normal lighting that provides appropriate visibility to the users, day and nightA standby lighting that provides minimum visibility to the users for allowing them to leave the

tunnel in their vehicles in case of power outage.

A lighting installation should be designed respecting several criteria, notably those relating to:

Level of luminosity and lighting on the pavementLevel of luminosity and lighting on the side walls and columnsValues of uniformity for the different operating regimensValues of glare.

Several types of installations are possible; the most common are symmetrical lighting and counter-flow lighting. Depending on the characteristics of the tunnel and the objectives defined, the lightingfittings may be installed in one or more lines, above the road, on top of walls of the tunnel...

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8.5. Ventilation

Ventilation in tunnelshas two functions:

In normal operation, it ensures sufficient air quality in the tunnel, generally by dilutingpollutants;

In a fire situation, it should make the environment as safe as possible to the tunnel users andrescue services by controlling the flow of smoke in an appropriate way : seeSections 1.6 & 1.7of the Report 05.16.B : "Role of the ventilation system during the self-evacuation phase" and"Role of the ventilation system during the fire-fighting phase".

Historically, the first reason for installing ventilation systems in tunnels was the reduction of pollutionlevels. Although the emissions of pollutants by road vehicles have decreased dramatically over the lastdecades, this function is still important and must be paid close attention at the design stage. In somecases, natural ventilation due to the piston effect of moving vehicles may be sufficient to fulfil the airquality requirements in normal operation. The need for a mechanical ventilation system is assessedconsidering the length of the tunnel and the traffic type (bidirectional or unidirectional) and conditions

(possibility of congestion) : seeTechnical Report 2004 05.14.B : Road tunnels: Vehicle emissions andair demand for ventilation. This report will be replaced by a new report to be published soon.

The same factors determine the requirements for ventilation in emergency situations, especially fire.The presence of other equipment or facilities, emergency exits for example, should also be taken intoaccount. Natural ventilation might be sufficient in some cases, but mechanical ventilation is oftenrequired for tunnels over a few hundred meters in length.

Different ventilation strategies may be used in tunnels. The choice between them is generally guidedessentially by fire safety considerations; the use of the system in normal operation is adjusted to suit :seeChapter V "Ventilation for fire and smoke control" of report 05.05.B 1999

The longitudinal strategy consists in creating a longitudinal air flow in the tunnel, in order to push allthe smoke produced by a burning vehicle on one side of the fire. If users are present on that side, they

may be affected by the toxic gases and reduced visibility, so the use of this strategy in bidirectionaland/or congested tunnels requires great caution. The minimum air velocity for successful smokecontrol depends on the design fire size and tunnel geometry (slope, cross-sectional area).

The transverse strategy takes advantage of the buoyancy of fire smoke: smoke tends to concentrate inthe upper part of the tunnel space, from where it can be mechanically extracted. The system isdesigned so as to preserve a fresh air layer in the lower part of the cross-section (correct visibility, lowtoxicity) which allows self-evacuation. It is therefore important to keep the longitudinal air flow aslow as possible in the fire region to avoid de-stratification and excessive longitudinal spread of smoke.

This strategy is applicable to any tunnel, but the design, construction and operation of the system aremore difficult and expensive.

The ventilation design process includes the computation of the minimum acceptable capacity of thesystem in terms of thrust and/or flow rates, the design of the ventilation network and the choice ofappropriate ventilation equipment Chapter 4 of the Report 2006 05.16.B : Ventilation and itsappendices 12.3 "Jet Fan calculation procedure", 12.4. "Smoke dampers" and 12.6. "Sound impact of

jet-fans". Ventilation equipment should meet a number of specifications, including resistance to fireand acoustic performance.

The design of appropriate ventilation control scenarios for each possible fire situation is a veryimportant part of the process : seeTechnical Report 2011 R02 : Road tunnels: Operational strategiesfor ventilation.These scenarios can be simple, especially when the longitudinal strategy is applied, orinvolve a large number of measurement and ventilation devices in complex, transverse-ventilatedtunnels. The optimisation of ventilation control for air quality considerations during normal operationis crucial to reduce energy consumption; it is an important issue since this consumption represents a

significant part of the operational cost of a tunnel.

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The interactions of the ventilation system design with other elements of a tunnel are numerous anddiverse. In the case of transverse ventilation, for example, the required flow rates may impact theexcavated section, with a potentially important impact on the construction cost. Ventilation alsoaccounts for a large part of a tunnel's power supply requirements. It interacts closely with other safetyequipment such as fire detection and fire fighting systems : seeChapter 5 "Fixed fire fighting systemsin the context of tunnel safety systems" of the Report 2008 R07.

The environmental issues linked to ventilation, besides the energy consumption and the related carbonfootprint, are linked to the localised, concentrated discharge of polluted air from the portals and stacks.Reducing their impact on the tunnel surroundings is part of good environmental design : seeSection 4.3. "Tunnel air dispersion technique", Section 4.6. "Operational aspects" and AppendixD. "Overview of dispersion modeling in designing ventilation systems"of the Report 2008 R04.

Finally, other parts of a tunnel than the main traffic space may require ventilation, most notably theemergency exits : seeSection 5.3. "Escape route design" of report 05.16.B 2006.
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8.6. Fire-fighting equipment for the users and emergency teams

8.6.1. Objectives

The primary objective of fire fighting equipment in a road tunnel is to provide the means to fight a fire

within the tunnel with minimum impact on the users, the emergency responders and the structure.The World Road Association (PIARC) has addressed the systems required for the fighting of fires inroad tunnels in numerous publications. This has been primarily in two publications;Technical Report05.05.B 1999 "Fire and Smoke Control in Road Tunnels" andTechnical Report 05.16.B 2007"Systems and Equipment for Fire and Smoke Control in Road Tunnels" . In addition these issues werealso covered in several Committee Reports to World Road Congresses specifically those held inVienna (1979), Sydney (1983), Brussels (1987), and Marrakesh (2001).

The systems critical to the ability to fight a fire within a road tunnel include: detection, alarm, radiocommunications, emergency telephone, closed circuit television, loudspeakers, water supply anddistribution, fixed fire fighting, portable fire extinguishers and emergency ventilation. These systemsmust be planned, evaluated, designed and installed in a careful thorough integrated manner to assure

that the systems are truly compatible and that the fire life safety of the tunnel is not beingcompromised or being over provided.

Many of these elements of the tunnel fire fighting systems are addressed in other chapters of thismanual. The systems included in other chapters provide detection (Section 8.3.5), fixed fire fighting(Section 8.7), fire alarms (Section 8.3), emergency telephones (Section 8.3.1), closed circuit television(Section 8.2), loudspeakers (Section 8.3.7), radio communications (Section 8.3), emergencyventilation (Section 8.5).

The systems addressed in this section relate to those systems provided for fire fighting in road tunnelsby the users (motorists), the operating agency and the fire brigade. These include systems designed tofurnish a supply of water through a fire line (standpipe) and fire hydrants (hose valves) and it theyinclude the installation of portable fire extinguishers within the road tunnel.

8.6.2. Water supply

A water supply system, including water mains, fire lines or standpipes, is required to provide water forfire fighting within the tunnel (through hydrants or hose valves) and to possibly provide water for afixed fire fighting system (Section 8.7) if installed in the tunnel (see Section VI.3.3 "Water supply" ofreport 05.05.B 1999). The source of water can be from a water distribution system or from a watertank.The required system pressure must match the requirements of the responding fire brigade.

8.6.3. Fire hydrants

Fire hydrants (hose valves) are required within the road tunnel to provide a point of connection for theFire Brigade to attach fire hose and gain access to the water supply. The hydrants should be installedat regular interval spacing within the tunnel (see Section VI.3.3 "Water supply" of report 05.05.B1999).The hydrant connections must be compatible with the responding local fire brigade(s).

8.6.4. Portable fire extinguishers

Portable fire extinguishers are provided at regular intervals within road tunnels to allow the (motorists)and operating personnel to fight a modest size fire within the tunnel prior to the arrival of the fireservices (seeSection VI.3.2 "Fire extinguishers" of report 05.05.B 1999).

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8.6.5. Fire hose

Fire hose reels are installed in road tunnels in some countries, however this is not a universal trend asother countries allow the fire brigade to bring their own hose into the tunnel for each incident (seeSection VI.3.3 "Water supply" of report 05.05.B 1999).
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8.7. Fixed Fire Fighting Systems

TheTechnical Report 2008 R07 "Road Tunnels: An Assessment of Fixed Fire Fighting Systems"summarises the World Road Association's views on Fixed Fire Fighting Systems (FFFS), and itsrecommendations pertaining to the applicability, selection and operation of such systems.

In a rapidly developing fire, smoke can quickly compromise the ability of users to self-rescue, whilerapidly elevating temperatures can make the tunnel untenable and destroy safety systems. An FFFShas the potential to reduce the rates of fire growth and spread, thereby assisting the safety of motoristsand the emergency services during the self-rescue and assisted-rescue phases of a fire. Other potentialbenefits of an FFFS are the protection of the tunnel assets from fire damage, and to avoid or reduce theroad network interruptions that may occur while a tunnel is being repaired following a fire incident.

Except where the installation of an FFFS is prescribed by a country's tunnel design guidelines, thefollowing steps are recommended to support the decision as to whether such a system should beinstalled:

a feasibility study,a risk analysis as outlined in theEuropean Directive 2004/54/EC;a cost-benefit analysis.

FFFS must be considered in the context of other critical safety systems such as ventilation. Rapid andaccurate incident detection and FFFS response are essential components to achieve the best possibleFFFS performance. The operational performance of FFFS can best be assessed through a systemengineering approach, including appropriate regimes for maintenance, testing and training. Carefulconsideration must be made with respect to the effects of such systems on operational procedures andmaintenance budgets

Water-based deluge systems are by far the most common type of FFFS installed in tunnels at present.Both low-pressure and high-pressure systems are available, with the latter having smaller dropletsizes. Other water-based systems, including foam systems, have also been installed in tunnels. The

selection of the appropriate FFFS should be based on cost-benefit analysis.

Although tunnel FFFS are used regularly in some countries, they remain the exception rather than therule in road tunnels world-wide. While such systems can reduce the rates of fire growth and spread,they also demand a higher level of maintenance and operational attention to ensure they function in anoptimal manner.

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8.8. Systems for surveillance and control of traffic

A traffic surveillance system is often installed when the level of traffic is very dense in a tunnel.Usually, a video-surveillance system is used, supplemented sometimes with counting devices. Avideo-surveillance installation offers the operator the possibility of controlling the traffic conditions inthe tunnel in real time. In case of degraded operation, it allows viewing the concerned incident zone sothat the needs may be rapidly evaluated.

Video-surveillance is thus a very valuable tool for the operator because it allows him, on the one hand,to watch continuously the incidents inside the tunnel and on the other hand, to react rapidly in case ofneed. However, in order to make full use of a video-surveillance installation, it is essential to maintaina human presence, if possible continuously, at the control-command centre.

A video-surveillance is generally quite simple in its conception. Cameras placed at regular intervals inthe tunnel provide a complete coverage of the tunnel and its surroundings. The images are thengrouped and transmitted by networks that may or may not be dedicated, to the control-commandcentre of the tunnel. The images are then received and viewed on the displays.

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8.9. Signposting

Signposting is one of the means available with the operator for communicating with the user.

For a given type of road, one can see in a tunnel the same signposting as in open air:

Fixed directional signpostingFixed police signposting (danger signs, speed limits and destination)Variable signposting (lane allocation signs, variable message signs).

The different safety devices available to the users in tunnel (emergency telephones, extinguishers,emergency exits...) require in addition a specific safety signposting.

The principal problem faced for signposting in tunnel is the location. In fact, the geometricalcharacteristics of an underground tunnel are optimised and increasing the transversal section will leadto significant surplus costs. In practice, a compromise must be found between the need for goodvisibility of the signs (therefore, panels sufficiently large) and the space available.

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8.10. Barriers

When a serious event (accident, fire, etc.) occurs in a tunnel, it must be possible to prevent at an earlystage the users from entering into the tunnel. In fact, a device preventing efficiently and rapidly entryinto the tunnel can allow not sending into a potentially dangerous situation users who are outside andwill also help prevent further accidents underground.

In many countries, experience shows that if the tunnel is closed simply by means of a stop signalplaced outside before the entrance, it is not quite effective. Therefore, this stop signal is oftencombined with barriers and variable message signs allowing the users to be informed of the reasonsfor closure.

The device closing the tunnel can be activated from the control-command centre or automatically intunnels that are not monitored continuously.

The closing device is meant for being used in emergency situations but it can also be used in othersituations, particularly during scheduled closures for maintenance interventions.

h l i i b i h

Documents

8. Equipment and Systems