Background of the invention The present invention relates to a method and a system configured to assist safe escape from a confined space in event of hazardous environmental or safety condition therein to humans present at least at one location of said space, the method using guide lights in event of such a condition, and the guide lights extending along said space, as defined in claim 1 and claim 17, respectively.

The present invention is as an outset concerned with the assisting of safe escape from a confined space in case of hazardous environmental or safety condition suddenly present in the space. Although the background of invention in a non-limiting sense is primarily discussed in connection with conditions inside road tunnels, similar or related issues fully or partly may also be present in one or more confined spaces such as a railway tunnel, a ship corridor or room, a building corridor or room, a train corridor, and an aircraft interior.

In the prior art US 2009/0066522- A 1 describes an evacuation system for use by persons in a tunnel or a large building. US 2014/0132183-A1, US 2012/0038479-A1 and US

2012/0181934-A1 describe a methods of assisting an evacuation using guide lighting, and WO 2012/114210-A1 describes further details of such guide lighting.

It case of e.g. fire, heavy smoke, collision or other accidents within a road tunnel space, irrespective of short or long tunnels, surface tunnels or subsea tunnels, it is vital that humans being present within said space can be safely evacuated from the space to a nearest safe space exit.

Although road monitors like cameras and fire detectors are installed in many tunnels, in particular long tunnels, and the monitors and sensors being under surveillance from a central monitoring office, in particular motor vehicle fires, caused by motor failure, brake overheating, collision between motor vehicles with associated impact caused fire, or collision with tunnel wall, may develop very quickly and not only causing risk of a spreading of the fire to other vehicles or tunnel interior, but indeed develop heavy and most dangerous heavy smoke, more than frequently reducing visibility inside the tunnel to a minimum. It is commonly know that humans in such critical situations very quickly become disoriented as regards proper way of escaping the serious condition within the tunnel. In many tunnels there are present stationary signs attached to the tunnel wall indicating distance to a nearest escape exit. However, although one escape exit may be just 50 meters away and another in the other direction being e.g. 200 meters way, the closest exit may indeed be the most dangerous to try to reach due to risk of suffocation caused by fumes, risk of explosion etc. Further, in case of rapidly developing and moving smoke, these prior art guide signs may be very difficult to see. These signs are typically fluorescent, and their visibility may more than often in a smoky atmosphere be difficult to observe or read. Movement in an unsafe direction from the site of an accident may be fatal and cause a respective human to die or be subjected to very serious health damages. Safe escape from the tunnel, either through escape-exit to a neighboring tunnel or to a safest one of the tunnel inlet and outlet are some preferred options, although safe escape rooms in some cases can be considered used. In case of heavy smoke or hazardous gas in a tunnel, overhead fans may contribute to a removal thereof. However, in case of an open fire, in a worst case on a vehicle carrying inflammable or easily combustible load, the fire may risk spreading or make safe escape difficult if the fans are set to rotate at maximum speed. The overhead fans are normally operated by environmentally well known controlled systems if the presence of CO2, NOX and/or visibility in the tunnel exceeds set thresholds. Such systems do not provide any signals to motorist or other humans in the tunnel, nor provide any information about tunnel escape exits. In particular in tunnels having an inclination or steep inclination at one or at either end, a fire in such a type of tunnel is of great concern, as in some cases the tunnel may act like a chimney causing the fire or smoke therefrom to spread rapidly. A quick escape to a nearest safe escape exit is therefore absolutely essential. Although escape issues are in particular importance for tunnels exceeding a length of 500 meters, similar issues may also be valid for even shorter tunnels. Short tunnels frequently do not have any incandescent lighting, and at night-time with darkness outdoors as well, this may cause problems in a situation of panic. So far, the background of the invention has been focused on issues related to road tunnels. In case of fire or accidents, e.g. de -railing, in a railway tunnel, it is essential that passengers on the train or subway are guided to a nearest exit in a safe manner, as in a railway tunnel there may be present health risks such a high voltage rails (in particular for modern subways). In case of a fire, a development of fumes or smoke, a water leakage onboard a ship, or a situation in which all passengers and crew must disembark or abandon the ship, in particular on a ship having multiple deck levels with associated labyrinths of narrow ship corridors, room and staircases, such as a large passenger ship or a cruise ship, it is essential as quickly as possible to evacuate people to a safe place. In a case where lighting in corridors fail or one more humans get disoriented about where they are and should move, the situation may escalate to fatal and chaotic escape attempts. Although exit signs may have been posted over doors and on walls, they may in a given situation not lead to a safe, nearest exit. A similar situation may arise in a building, such as a large department store or a large office building or a hotel, where it is difficult to find a safe way out via corridors or large display rooms, e.g. large furniture shops.

In corridors of trains wagons it may in certain situations be helpful to be guided to a nearest safe wagon exit. Further, in a situation where it is necessary for all passengers and crew to quickly exit an aircraft in case of emergency, it is essential that passengers are guided to a the nearest safe exit, e.g. only on starboard side and at the rear, in case it is unsafe to exit on the port side of the aircraft. Currently there is only a green light line lit in the floor in the aircraft without indication of whether to move along the aisle in forward or rearward direction to most quickly and safely exit the aircraft. Summary of the Invention

The present invention intends to provide in a simple and efficient manner a method and a system to assist a safe escape for humans from a confined space in event of hazardous environmental or safety condition, i.e. an emergency situation, as indicated in the preamble of claims 1 and 17, respectively.

According to the invention, the method provides that the guide lights are installed along the confined space as an array of guide light unit modules with associated hazard and/or accident condition sensors, and that upon occurrence of such condition a plurality of guide lights are adaptively operable to guide said humans by way of light signals away from said at least one location to at least one nearest safe space exit or in at least two directions to one nearest safe space exit or respective ones of a plurality of safe space exits.

Further embodiments of the method are apparent from the attached sub-claims.

According to the invention, the system comprises at least one control unit, a plurality of condition sensor units in communication with the control unit, a plurality guide lights with their lighting operation and mode controllable by said control unit, and at least one power supply, and the plurality of guide lights are installed along the confined space as an array of guide light unit modules with associated hazard and/or accident condition sensors.

Suitably, each of the light units and their respective associated condition sensors are arranged as an array of single modules or pairs of modules.

Further embodiments of the system are apparent from the attached sub-claims.

The invention provides for an efficient and safe manner for humans to exit a confined space to thereby reach a nearest safe space exit.

In some, although not all, cases, it may be preferable to let guide light modules be at a height level of a conventional hand rail, or with low hand rails the modules could serve as the hand rails as such if escaping persons need to keep low in the tunnel due to smoke.

Non-limiting aspects and embodiments of the invention will now be described and shown with reference to the attached drawings.

The invention will mainly be explained with reference to a road tunnel application of the invention and being a non-limiting type of confined space. However, more labyrinth-like confined spaces will also be discussed, related to indoor ship decks or office/ hotel building structures.

Brief Description of the Drawings Fig. 1 shows a longitudinal section of a tunnel exhibiting a guide light installation in idle state.

Fig. 2 shows a transverse section of the tunnel in Fig. 1, with section I-I being that shown in Fig.l.

Fig. 3 shows an enlarged view of section III.

Fig. 4 shows a longitudinal section of a tunnel exhibiting a guide light installation in active escape assisting state.

Fig. 5 shows a transverse section of the tunnel in Fig. 4, with section IV-IV being that shown in Fig.4. Fig. 6 shows an enlarged view of section VI in Fig. 4. Fig. 7 shows an enlarged view of section VII in Fig.4

Fig. 8 shows a longitudinal section of a tunnel exhibiting a guide light installation in active escape assisting state.

Fig. 9 shows a transverse section of the tunnel in Fig. 8, with section VIII- VIII being that shown in Fig. 8. Fig. 10 shows an enlarged view of section X in Fig. 8.

Fig. 11 shows an enlarged view of section XI in Fig.8.

Fig. 12 shows as an example a guide light installation in active escape assisting state in a confined space being a deck level of a ship or an office floor with escape ways via staircases.

Fig. 13 shows a variant of the example in Fig. 12. Fig. 14 illustrates alternative locations for installing escape guide light in a confined spaces such as e.g. corridors in a ship, an office building, or hotel building.

Fig. 15 shows as example a LED matrix a guide light device in idle or passive state.

Fig. 16 shows as example the LED matrix in Fig. 15 with the a guide light device escape assisting state.

Fig. 17 is a simplified block schematic diagram illustrating a basic principle of a system according to the invention.

Fig. 18 is a first aspect of a tunnel installation of the system.

Fig. 19 is a second aspect of the tunnel installation of the system

Fig. 20 is a simplified block schematic diagram illustrating further the basic principle of the system according to the invention with reference to use of LED matrix.

Fig. 21 illustrates as an example various possibilities of power and signal interconnection between adjacent modules in an array of modules which exhibit guide lights and sensors.

Detailed Description of the Preferred Embodiments

The invention now to be further explained comprises a method and a system which are adaptive to effectively assist safe escape from a confined space in event of hazardous environmental or safety condition therein to humans present at least at one location of said space. As already explained, in the prior art it is common to use guide lights in event of such a condition, the guide lights extending along said space. Such known guide lights seen e.g. on aircraft floor and on cruise-ships do not in any way guide a person to the nearest safe exit. In a critical situation when ambient light disappears, panic may easily occur as regards the choice of a quickest way to escape from the confined space.

The invention will now primarily be explained with reference to use in a confined space such as a road tunnel 1. In an idle state of the system of the invention, i.e. when no emergency situation is present, it is possible to let the guide lights substantially exhibit a stationary lit line 2 of guide light display. Although not shown, the line 2 may appear as a dotted line. The guide lights presenting the line are suitably installed a dustproof and watertight enclosure 3, suitably of IP66 standard, which is attachable to a wall 1' of the tunnel 1.

Upon occurrence of the event of a hazardous environmental or safety condition at a location 4 such as e.g. a vehicle colliding with the tunnel wall 1', two or more vehicles colliding in the tunnel, engine fire in a vehicle or load of a vehicle having caught fire, a plurality of guide lights are adaptively operable to guide said humans by way of light signals away from said at least one location and to at least one nearest safe space exit. More specifically, guide lights 5 and 6 may be caused to lead away from said location 4 in at least two directions to one nearest safe space exit 7; 8 , in this case the respective ends of the tunnel 1, or respective ones of a plurality of safe space exits, e.g. transverse tunnel escape passages to a neighboring tunnel (not shown).

In a non-limiting embodiment, the guide lights 5; 6 are suitably arrow-shaped, the guide arrows pointing away from said location in direction to said one exit 7; 8 or to respective ones of said plurality of exits.

In the example of Fig. 2, the distance from the left end 7 of the tunnel 1 to location 4 is e.g. 190 meters, and from location 4 to the right end 8 of the tunnel 1 is e.g. 80 meters.

In an accident situation such as shown on Fig. 4, it will be appreciated that the invention immediately provides for adaptively guiding humans present in the tunnel safely away from the location of an accident or a safety risk. Even in the case of a hazardous condition at a location 9 close to a tunnel end 7, as shown on Fig. 8, humans being in the tunnel 1 between the location 9 and the tunnel end 8 will be guided to the tunnel exit being its end 8, even though it is a substantially longer distance , e.g. 970 meters, than a distance of e.g. 120 meters between location 9 and the tunnel end 7.

As will be further explained with reference to Figs. 17 - 20, along the distance which the guide lights extend, there are located sensors in or on guide light modules or specific sensor modules at regular intervals. If an accident occurs at a location and sensors detect the condition, the direction which the guide lights 5; 6 should point will adaptively be

determined, irrespective of the location of such an anomaly condition along the length of the tunnel. Suitably, the guide lights 5; 6 can be operated in a pulsating fashion. As an alternative, the guide lights 5; 6 could operate in succession so as to repeatedly exhibit light movement from said location of the anomaly condition towards said one exit or towards respective ones of said plurality of exits. In the event of smoke in the tunnel, e.g. due to a heavy fire, guide lights which pulsate or "move" will be more readily observable to humans who may even be in state of panic.

In a further example of the use of the invention, with reference to Fig. 12 and 13, the location of a hazardous condition 10; 11 could e.g. be on a ship deck or on a floor of an office building or a hotel building, in which case the guiding through use of adaptively operated guide lights is made to a nearest safe exit which in the non-limiting example could be a pair of staircases 12; 13 and 14; 15.

The guide lights 2; 5; 6 are suitably installable in modular form as modules onto or into at least one of a ceiling installation 16, a floor installation 17, an installation 18 on a wall of said space or a skirting between the wall and floor, and a banister or a hand rail 19. This mode of installation, where one or more of the possible installations 16 - 19 are used, is specifically useful in corridors, in particular narrow corridors. It will be readily appreciated that the IP66 type enclosure 3 used in tunnels can, in case of emergency and when the visibility is poor due to smoke in the tunnel 1 and no ambient lighting, can be used as a hand rail.

Although the confined space could be one of a road tunnel, a ship corridor or room, and a building corridor or room, the space could also be a railway tunnel, a train corridor, and an aircraft interior.

As already discussed, the guide lights 2; 5; 6 are switchable between a) an idle state exhibiting at least one non-movable light line 2 or an array of segments thereof, and b) a triggered state caused by the event of at least one occurred hazardous environmental condition, yielding that e.g. arrow like or "moveable" guide lights 5; 6 become active. As a non-limiting example, the guide lights 2; 5; 6 could be presented through use of e.g. a LED- matrix 20, as shown on Figs. 15 and 16. In the non-limiting example, the matrix has 75 LEDs, comprised by five rows and fifteen columns. In the idle or passive state of the guide lights, i.e. the line 2 of guide lights, all of the fifteen LEDs in row C are activated and remain on in a stationary state.

In a non-limiting example the escape assisting state of the guide lights, such as guide light 6 being arrow shaped, then in the panel of LEDs 20, LEDs Al, A2, A4, A5, A7, A8, A10, Al l, A13, A14 and El, E2, E4, E5, E7, E8, E10, El l, E13, E14 in rows A and E will be on, LEDs B2, B3, B5, B6, B8, B9, B l l, B 12, B 14, B 15 and D2, D3, D5, D6, D8, D9, Dl l, D12, D14, D15 in rows B and D will be on, and LEDs CI, C3, C4, C6, C7, C9, CIO, C12, C13, C15 in row C will be on.

If a "fat" arrow 6 is to move from left to right, successive operations of the LEDs in the matrix will occur, letters corresponding to the activated row(s), and the number figure corresponding to the activated matrix column:

a) AE1, ABDE2, BCD3, C4

b) AE2, ABDE3, BCD4, C5

c) AE3, ABDE4, BCD5, C6

d) AE4, ABDE5, BCD6, C7

e) AE5, ABDE6, BCD7, C8

f) AE6, ABDE7, BCD8, C9

g) AE7, ABDE8, BCD9, CIO

h) AE8, ABDE9, BCD10, Cl l

i) AE9, ABDE10, BCD11, C12

j) AE10, ABDE11, BCD12, C13

k) AE11, ABDE12, BCD13, C14

1) AE12, ABDE13, BCD14, C15

As indicated above, in an idle state of the system of the invention, it is possible to let the guide lights substantially exhibit a stationary lit line 2 of guide light display, and the line 2 may appear as a dotted line if the line 2 is constituted by a plurality of light sources. In case of an accident or an emergency situation, the line 2 may be caused to "move" in a direction of the nearest safe exit, or with reference to an accident or emergency location in one or two directions. As non-limiting example and with reference to Fig. 15, the "movement" of line 2 can be effected by causing the light sources CI, C2, C3, C4, C5, C6, C7, C8, C9, CIO, Cl l, C12, C13, C14, C15 to be lit in succession, e.g. one by one, or two, three, four or five at a time.

As indicated on Figs. 18 and 19 it is possible to establish an array of guide light unit modules 31; 32. In the case of using arrows 5; 6, the arrows may e.g. all pulsate or "flash" on all modules simultaneously, or "move" on each module so as to present multiple sets of moving arrows. In the case of the line 2, the line 2 on each module may e.g. "move" as indicated above to yield multiple sets of "moving lines", or the modules 31; 32 may e.g. present in succession a flashing line, either by successive activation of the modules one by one, or two by two. Alternative modes of "movement" or flashing are conceivable without departing from the concept of the invention.

Further, it is also conceivable to operate with a combination of arrows and lines, e.g. one module exhibiting stationary or moving arrows and a next one exhibiting a stationary or movable line. If a "moving" or stationary line is a preferred mode of operation, modules close or next to a safe exit could e.g. exhibit stationary or movable arrows.

For an emergency situation in a long tunnel or corridor, the number of modules to be activated could be substantial, thus requiring a high power consumption. In case external power supply to the modules then fail, power supply must be based on internal emergency or stand-by batteries in each module. In such a situation, the line embodiment would be a preferred one as described above, although it could be possible to simply use more "narrow" or "lean" arrow 6, yielding moving arrows 6 as follows:

m) AE1, BD2, C3

n) AE2, BD3, C4

o) AE3, BD4, C5

P) AE4, BD5, C6

q) AE5, BD6, C7

r) AE6, BD7, C8

s) AE7, BD8, C9

t) AE8, BD9, CIO u) AE9, BD10, Cl l

v) AE10, BD11, C12

w) AE11, BD12, C13

x) AE12, BD13, C14

y) AE13, BD14, C15

Compared to the configuration on Fig. 16, the succession indicated by m) - y) triggers five LEDs at a time, instead ten LEDs at a time as indicated by the succession a) - 1). However, the succession m) - y) is more power consuming than triggering one or two LEDs at a time in the line embodiment. From a power consumption aspect, the line embodiment is currently a preferred one.

Although use of a LED-matrix 20 is a currently preferred embodiment for creating the required lighting effects of the guide lights 2; 5; 6, alternative types of guide lights may be considered within the scope of the invention.

The system part of the invention is now to be further described with reference Figs. 17 - 21

The system comprises at least one control unit 21, a plurality of condition sensor units 22 - 28 in communication with the control unit 21, a plurality guide lights 2; 5; 6 with their lighting operation and mode controllable by said control unit 21, and at least one power supply 29. In an application of the invention related to e.g. road tunnels, for safe operation a control unit 21 and a power supply are provided at either end of the tunnel, indicated by an apparatus 30. It will be appreciated that e.g. a vehicle collision with a tunnel wall 1' could damage power and signal communication between such collision location and an end of the tunnel not having an apparatus 30. Upon the control units 21 detecting that there is an "event" at a location along the array of light display modules and sensors, the control units 21 will adaptively trigger the guide lights 5; 6 to be in an ON or activated state and direct humans present in the tunnel away from the location of the event or anomaly condition to safe tunnel exit place, e.g. tunnel end openings 7; 8.

However, in an array of guide light unit modules 31; 32 with associated sensors 22 - 28, 33- 35, the control unit 21 must be located at least at one end of the array, and power from the power supply 29 should deliverable from such at least one end of the array. In more complex escape route layout, such as disclosed on Figs. 12 and 13, one master control unit with power supply and a plurality of slave control units with power supplies could be required.

As indicated on Figs. 18 and 19, the plurality of guide lights are present as a plurality of guide light unit modules 31; 32. Sensors may also be located inside or on the units 32, and in some cases also inside the units 31, although sensors will then preferably be located in individual sensor units 24 located between modules 31.

The lighting units 31; 32 are each suitably, but not necessarily, composed of a matrix of the selective controllable LEDs 20, as described above, and will be operated by the at least one control unit 21. As described above, the matrix of LEDs are operable to present at least one of: a) one or more non-movable idle state light lines or even dotted lines, b) successively in one of two directions operable and thereby "movable" LED's, c) one or more arrow-like sets of LED's, d) successively operated or flashing arrow-like sets of LED's, e) successively operated dot-or point-like LED's, f) message in the form of text and/or symbols, and g) successively movable text letters and/or symbols.

As mentioned, at least one type of condition sensor 22 - 28 is provided. There could be provided plurality of spaced apart sensor units either located as individual sensor unit or sensor modules 24 spaced between and connected to respective ones of adjacent guide light unit modules 31, or be located in or on, or attached to respective ones of guide light unit modules 32.

In order to test on-site that a specific module works as intended, i.e. to operate individually as well as to be able to trigger further modules in a neighboring array, a manually operable trigger switch 25 can be associated with each guide light unit module 32 or with each sensor unit module 24. Such a switch 25 is to be operable by authorized personnel only and could be a key-type switch or an NFC assisted switch. The sensor units 24 may include at least one of high-G impact sensor 33, fire sensor and/or extreme heat sensor 34, and hazardous gas or smoke sensor 35, as shown on Fig. 20. The sensor 33 could be implemented as sensors 27; 28 on Fig. 17. In a non-limiting example, the sensors 27; 28 could be located on the rear of the enclosure 3. Upon a vehicle making a hard collision with a tunnel wall 1', the housing or enclosure 3 at such location will be heavily damaged and cause impact and compression on a rear mounting part 3' on the enclosure. G- impact sensors are well known and are available in a number of types, e.g. Wheatstone bridge circuit fitted beams. The sensors 34 and 35 are suitably related to sensor 26 being a twin-type sensor. Detecting fire and visible flames can be e.g. be through use of heat temperature sensitive camera or infra-red detectors. It may also be possible to locate a heat sensor and/ or smoke sensor 36 inside the enclosure 3. An application of the fire sensor and/or extreme heat sensor 34 is to enable to detect flames and/or excessive heat from a vehicle and/or its towed trailer, e.g. from any one of the vehicle engine region, exhaust system, wheel hubs (rotary bearings), wheel brakes, tires, and any carried load. Thus, if a sensor 34 in one module detects any anomaly, it may communicate it to a next module and/or to an external central surveillance station. If the next modules successively detect similar anomalies or increasing states of anomaly, this may e,g. yield at least one of: raising an alarm, alerting other vehicles in the tunnel by transmitting traffic hazard information to radios in the other vehicle, cause an entry to a tunnel to be closed, and trigger emergency services to rush to the tunnel or tunnel exits. If there is detected not only fire and/or excessive heat by the sensors 34, but also smoke by the sensors 35, and/or any of the hazards by the sensors 36, it will be possible to obtain improved assessment of seriousness of the hazards that seem to have become present.

It is well known that e.g. vehicle and/or train tunnels have in the ceiling thereof and/or on the walls thereof monitors or cameras. Normally, such monitors or cameras are controlled manually from an external, remote monitoring station 39. In view of each module being able to be in communication with the station 39, it is possible - based on the signal contents in such communication - to cause movement of the monitors or cameras to be automatically controllable by each module in an array or by successive groups of modules, thereby to be able follow at least one hazard vehicle in the tunnel if such vehicle may be the cause of an imminent emergency situation.

It should be emphasized that a major concern is to get such a hazard vehicle out of the enclosed space of a tunnel. Personnel at the monitoring station 39 will decide whether an emergency situation exists and whether persons in other vehicles in the tunnel need to evacuate the tunnel as fast as possible, e.g. via safe emergency exits in the tunnel or via inlet or outlet end regions of the tunnel.

Each control unit 21 may suitably communicate via cable 37 and/or wireless communication 38 with an external, remote monitoring station 39. Further, upon an anomaly condition being triggered by the system, in the non-limiting case of use in tunnels, the control unit 21 may communicate with displays 40 inside the tunnel 1 to present readable information through use of text displays or through use of traffic signs already in the tunnel 1, and displays and/ or road bars 41 being activated outside the tunnel entrance, thus preventing further vehicles or humans entering the tunnel.

As further indicated on Fig. 20, the pair of control units 21 may communicate via a cable 42 extending through the array of modules 24; 31 or 32. Further, each control unit should preferably also communicate via cable 43 with and power a microprocessor 44 inside the enclosure. The microprocessor 44 has suitably a unique address in order promptly to inform the control unit 21 whenever anyone of the sensors 22-28; 33-36 have operated to trigger the microprocessor 44 and thereby the control unit 21 and caused operation of the escape lights 5: 6. If the microprocessor 44 in a specific module 31; 32 has failed, e.g. due to a vehicle collision with the tunnel wall 1' and thereby destroying the module, the control unit 21 can immediately determine that such specific and identifiable module has been destroyed and that failure signals are detected. In view of all microprocessors in the modules

intercommunicating either from module to module to the control unit at an end, or each communicating directly with the control unit 21, it will be quick to determine a location of an "event".

The microprocessor 44 can be designed to control a LED matrix 20 via row terminals 20' and column terminals 20'.

In a situation where external power delivery to the modules fails, each guide light unit module may have an internal back-up battery 45 to operate hazard caused triggered operation of the guide lights 5; 6; 31; 32. The battery 45 may be a heavy duty type to operate as main power source for each module in any case of failure of external power supply. Suitably, the battery 45 is chargeable. External power supply to the modules could e.g. be provided at regular intervals along the length of a tunnel or long corridor, e.g. at intervals of 1.0 - 1.5 kilometers, although smaller intervals in the range 0.1 - 1.0 kilometers are conceivable. In other applications, the intervals could be different to suit preferable installation requiremnents.

In such a case, when e.g. sensors associated with a module midway in the tunnel trigger operation of a microprocessor 44 in the module, other processors in modules on either side of that mid-way module will detect the triggering and automatically operate escape arrows 5; 6 pointing away from the midway module. If no "operation OK" are signals received at regular intervals from the control units 21 in such a case, road bars may automatically go down to block entrance to the tunnel and external warning lights flash.

The modules 24; 31; 32 may suitably be attached to an enclosure holder 46 which in turn can be snap fitted onto a wall bracket 47. The enclosure 3 has suitably a front window 48 to cover an opening 3" on the front of the enclosure 3. The enclosure 3 is suitably made from plastics material, metal or metal alloy. Suitably, the enclosure 3 is made via an extrusion process. Method of attachment of the window 48 onto the enclosure 3 is dependent on mutual compatibility of their materials, but a way of attachment may be through use of adhesive or double-sided adhesive tape. In view of a dusty atmosphere in a tunnel and lateral "spraying" of road particles caused by passing vehicles, as well as service cleaning of the tunnel, a window saving option could be to provide the window 48 with a transparent and easily replaceable front cover (not shown) which can be replaced at regular maintenance intervals. The replacement of the front cover is made externally of the module and will not have any influence on the IP66 standard protection on the modules in the system.

In case any control unit 21 detects in a module 24; 31; 32 a malfunction not caused by any hazardous event or anomaly condition, such a module can be easily replaced. If the module has become defective through a hazardous event, e.g. through a vehicle colliding with the module, the module can also be easily replaced. The module may swiftly be released from its snap attachment with the wall bracket 47 and pulled out from the space it had between a pair of neighboring modules.

As shown rather schematically on Fig. 21, intercommunication between modules 24; 31; 32, which in turn communicate with the control unit(s) 21, can be effected via at least one of: optical communication devices 49, NFC- signal transfer devices 50, Bluetooth communication devices 51, inductive power transfer devices 52, and wired connection 53 with plug part 53', socket part 53" and cable 53'".

As non-limiting example, the sensor module 24 could e.g. have a length of 0.2 - 0.5 meters and modules 31; 32 could e.g. be 1 - 10 meters long. Other length ranges are conceivable, dependent on configuration of displays and sensors used, as well as installation environment.