Maritime University of Szczecin
Akademia Morska w Szczecinie
2011, 26(98) pp. 75–79 2011, 26(98) s. 75–79
Problems associated with evacuation direction choice in case
the emergency situation at passenger ship
Problemy związane z wyborem kierunku ewakuacji
w sytuacjach awaryjnych na statkach pasażerskich
Dorota Łozowicka
Maritime University of Szczecin, Faculty of Navigation, Institut of Marine Navigation Akademia Morska w Szczecinie, Wydział Nawigacyjny, Instytut Nawigacji Morskiej 70-500 Szczecin, ul. Wały Chrobrego 1–2
Key words: evacuation, passenger ship, human factor, modeling, genetic algorithm Abstract
Shortening the time of evacuation itself is affected, among other things, by the geometry of evacuation routes and their appropriate marking. At the paper interactions between people and systems of evacuation routes signing at evacuation models are described. Also human psych-physiological reactions in the conditions of dangerous situations are analyzed. Influence of evacuation direction choice and „bottle necks” for evacuation time at exampling passenger ship is presented.
Słowa kluczowe: ewakuacja, statek pasażerski, czynnik ludzki, modelowanie, algorytm genetyczny Abstrakt
Skrócenie czasu ewakuacji może być osiągnięte między innymi poprzez odpowiednie zaprojektowanie dróg ewakuacji oraz ich właściwe oznakowanie. W artykule przedstawiono interakcje pomiędzy ludźmi a syste-mami oznakowania dróg ewakuacji w modelach ewakuacji. Ponadto przedstawiono psychofizyczne reakcje człowieka w warunkach zagrożenia. Wpływ wyboru kierunku ewakuacji na czas ewakuacji i zjawisko po-wstawania zatorów na drogach ewakuacji omówiono na przykładzie wybranego statku pasażerskiego.
Introduction – the reasons of evacuation
delay
The reasons of evacuation delay can be re-stricted by evacuation starting delay, non-optimal evacuation direction choice, present of obstacles at evacuation routes and other reasons, which should be eliminated if it is possible. The problem of way finding could be one of the main reasons of evacua-tion delay.
Evacuation systems should ensure acceptable level of safety of evacuation procedures. In the case, when it is impossible to avoid a situation enforcing evacuation (e.g. fire, collision), it should be attempted to lengthen the time available for evacuation, to shorten evacuation time, and also to shorten the time of becoming aware of the necessity of abandoning the vessel.
Shortening the time of evacuation itself is af-fected, among other things, by the geometry of evacuation routes and their appropriate marking. Proper information plays an essential role in condi-tions of threat, enabling man to make the right deci-sion concerning the direction of evacuation. In a labyrinth of routes, frequently in conditions of restricted visibility, man faces the necessity of choosing the direction of further route at each en-countered bifurcation. The decision is made in a state of strong nervousness caused by the existing menace. Man finds himself in a situation unusual for him and even a simple layout of corridors does not warrant his avoiding straying and wandering around the same paths. An appropriate combination of lighting and evacuation marking permits a fast and safe evacuation of people from the place of threat.
Interactions between people and systems of evacuation routes signing at evacuation models
A convenient and ever more widely used form of analyzing the evacuation course is the applica-tion of computer evacuaapplica-tion models. The following can be counted among the best known: EVACNET, EGRESS, EXODUS, SIMULEX, CESARE, BY-PASS.
With respect to the way of modeling people’s flow, computer evacuation models can be divided into macroscopic and microscopic. In macroscopic methods the translocation of people as a homoge-neous mass is taken into consideration. The direc-tion and speed of evacuadirec-tion are determined only by physical values (size of population, patency of emergency passages). The details of evacuation are determined not by individual features, but by the number of escapees. In microscopic models trans-location is combined with behavior. Not only are physical conditions analyzed, but each person is treated individually; his responses to external sti-muli are taken into consideration (personal reaction time, choice of escape route). In these models, per-sonal attributes in translocation and in the process of making decisions are taken into consideration. This process is independent of other people’s beha-vior, which takes part in the simulation, and takes account of individual trajectories. Having the re-quired information about the surroundings, people decide how to respond.
The most of the models describing people mov-ing do not take into consideration interactions be-tween people and systems of evacuation routes signing. It is assumed that people know evacuation route, but it is not always true in real evacuation process (especially at large passenger ships).
The example of the model including evacuation router signing system is building EXODUS (analo-gue maritime EXODUS for land building applica-tion). System VCA (Visibility Catchment Area) is included into this model. VCA is defined as a re-gion of space from where it is possible to visually receive information from evacuation signing [1]. Within this model, the maximum viewing distance is currently arbitrarily set as a distance specified in regulations [2].
Evacuation routes signing based on
investigation of human psych-physiological reactions
Guidelines referring evacuation signs should be preceded by investigation of human psych-physio-logical reactions in the conditions of dangerous
situations. It is necessary to fix the signing systems to human perceptions. It is known that people in stressed situations have increased blood pressure, increased heartbeat, eyes wide open.
At [3] the psych-physiological responses during the evacuation using eye, tracking instrument (pro-duced by Senso Motoric Instrument) was analyzed. The results of experiment were useful for the set-ting principles of safety signs. The conclusions were following:
“The safety signs should be set up at the upper level of the very front of people’s eyesight, the best situation is that safety signs can be seen from every position in the stadium;
interferences such as advertisement board should be eliminated around safety signs; safety signs should be established successively
until to the exit;
the size of safety signs should be large in order to the obvious;
the color used should be traditional white back-ground with green character using the reflective traffic paint, and the light should be soft.” Relationship between evacuation signs dimen-sions, observation angle and maximum view dis-tance is considered at [1]. Maximum view disdis-tance in function of observation angle is fixed. Relation-ship between maximum view distance and observa-tion angle is nonlinear and consistent for each of analyzed types of sign (two plastic signs and one photo luminescent sign. The experiment was per-formed in a corridor 39 meters in length with artifi-cial illumination along its length.
Computer simulations of evacuation and guide-lines for evacuation time estimating base on the assumption, that people move by the evacuation routes without hesitating and mistakes. It is not too realistic assumption. In real evacuation process passengers need the leaders. Crew member are trained. They can direct the passengers by the pro-per verbal commands. They should have noticeable characteristic clothes and IDs.
During real evacuation panic and chaos should be assumed. In the absence of the crew members, passengers should find assembly station using only evacuation signs. Despite the IMO rules evacuation sings are not always according to the standards.
In 1993 TNO [4] made an experiment with people, who were looking for the assembly station using only evacuation signs. Evacuation time was almost two times longer than usually.
TNO tested new systems of evacuation signing. First system based on “moving” lights (turning off and turning on the bulbs) giving an information
about the direction of evacuation. This system could be useful in case the inaccessibility of evacu-ation routes for example in fire. Experiments results disappointed, because system was not visible in normal lightening. Next system based on low photo luminescent arrows. This system gave the possibili-ty to avoid the 90% mistakes during the evacuation. The disadvantage of the system is aging of photo luminescent materials. Zink and sulfur ingredients should be removed every 3–5 years [4].
Rules and guidelines referring evacuation routes signing
According to SOLAS’74 rules, except emergen-cy lightening, evacuation routes, including stair-cases and exits, should have lighting or photo lumi-nescent indicators fixed 0.3 m above the deck at all points of evacuation routes crossing and branching where people have to decide about future evacua-tion direcevacua-tion. This signing should be clear for the passengers and should take under consideration language differences (SOLAS, II-2/28).
Necessary information for evacuation in case the fire should be given well visible to instructions for passengers, proper signing the evacuation routes, exits and directions of evacuation, places where fire protection devices are keeping and the places with hazardous materials (ISO 3864-1:2002).
At the evacuation routes, except evacuation signs, additionally signing can be used such as pho-to luminescent material. This material consists the pigments which cumulate energy from normal ligh-tening and emit this energy as a yellow-green glow during the normal lights are turning off. Material is visible for the eye which is adapted for the dark-ness. In smoke conditions ccontinuous line is fixed one meter over the deck is better indicator of evac-uation route then traditional emergency lightening which is fixed on the ceiling ad wall. This system is useful for finding the exit where people might have doubts about the direction of evacuation. Every slopes and obstacles at evacuation routes can be signed in such way. Photo luminescent bells give un information in case the lack of lightening and smoke. They are made of toxic and non-radioactive material which is resistant for fire and damages (IMO Res. A.752(18)).
Resolution A.752(18) accepted in the 4th No-vember 1993 describes using low lightening at pas-senger ships. In case the emergency lightening does not give enough light because of smoke at the pas-senger ships (carrying more than 36 paspas-sengers) low light location (LLL) should be used. It could help for easy identification of evacuation routes and
safe evacuation of passengers. LLL system consists of extruded aluminum and insert photo luminescent rigid board. It should be fixed at least one side of the corridor, and also bulkhead.
An interesting concept is the suggestion of sig-naling the direction of evacuation by means of sound, bound strictly with the way man’s instru-ment of hearing functions and the way of locating the source of sound. Man’s instrument of hearing is essentially a mechanical system very sensitive to small changes in the surrounding sound waves. A sound wave emitted from a certain source first reaches the ear situated closer. On the basis of vari-ous pressures in each of the ear channels, man is able to locate the source of sound [5]. During expe-rimental evacuation of ferries [6] evacuation time was in many cases shortened by 30%.
Influence of evacuation direction choice and „bottle necks” for evacuation time at exampling passenger ship
Wrong evacuation routes signing could be the reason an incorrect decision about evacuation direc-tion. Following calculations of evacuation time are made with taking into consideration such parame-ters as initial passenger’s distribution and different options of evacuation direction choice.
Genetic algorithm methods were used. Geome-try of evacuation routes was coded with fixing of genetic operator (mutation, crossover) for non-binary type of coding [7]. In case the possibility of two evacuation routes option passengers are not distributed proportionally to the evacuation routes width, but their number is fixed randomly.
Exemplary passenger ship is taken into the anal-ysis. Its geometry is described as shown at figure 1. The ship is very typical. It has two staircases used by passengers to move to assembly stations at boat deck.
The ship has got two decks with 442 people on board. During the evacuation people follow to the upper deck to assembly station.
At the first iteration of genetic algorithm (initial population) evacuation time for different distribu-tion of passengers and different evacuadistribu-tion routes choice was from 529 to 829 seconds. Maximal evacuation time in seventh iteration was 895 seconds. Algorithm has reached convergence in 20’Th iteration. The maximal evacuation time was 950 seconds (Fig. 2).
Comprising results (Fig. 2) with simulations de-scribed at [7] without taking under consideration evacuation route choice, it is noticed that evacua-tion time increases about 30%.
Fig. 1. Evacuation routes geometry schema (C – corridor, D – doors, PS – public space, S – stair, DP – assembly station) Rys. 1. Schemat rozkładu dróg ewakuacji (C – korytarz, D – drzwi, PS – pomieszczenie publiczne, S – schody, DP – miej-sce zbiórki)
Fig. 2. Minimal and maximal evacuation time for different iterations
Rys. 2. Minimalny i maksymalny czas ewakuacji dla poszcze-gólnych iteracji
Above calculations of evacuation time are the results of simulations performed on one example of ship. This passenger ship was chosen to the simula-tion because it is very typical. Similar analysis can be performed for large passenger ships with every main fire zone with two stair cases.
Fig. 3. Initial distribution of passengers and the number of persons following by evacuation routes for the shortest evacua-tion time
Rys. 3. Początkowe rozmieszczenie pasażerów i liczba osób podążających daną drogą ewakuacyjną dla najkrótszego czasu ewakuacji
Fig. 4. Initial distribution of passengers and the number of persons following by evacuation routes for the longest evacua-tion time
Rys. 4. Początkowe rozmieszczenie pasażerów i liczba osób podążających daną drogą ewakuacyjną dla najdłuższego czasu ewakuacji
Conclusions
In recent years all forms of relaxation at sea have become immensely popular. The present day trends to build very large vessels necessitate the
500 550 600 650 700 750 800 850 900 950 1000 1 5 7 9 15 20 25 Ev ac ua ti on ti m e [s] Iteration minimal evacuation time maximal evacuation time
1 1 2 10 12 2 2 6 59 11 17 70 57 29 41 1 4 62 0 2 63 0 0 0 0 DP1 DP2 Upper deck Lower deck tc = 950 s 4 17 1 11 61 217 5 8 0 3 57 55 0 14 2 1 9 64 51 0 0 DP DP Upper deck 60 49 9 5 81 10 Lower deck 1 10 2 51 24 57 23 5 63 5 63 0 0 tc = 529 s 67 31 8 2 4 22 0 0 4 Upper deck PS2 S2 PS1 S1 C3 C4 C1 C2 D1 D2 DP1 DP2 Lower deck PS1 S1 C3 C4 C1 C2 C7 C5 C8 C6 D1 D2 S2 C9 C10
safety systems of these vessels to be constantly improved. Up till now, there have been a lot of problems which have not been solved in the field of ship technical systems and construction safety. This state has been confirmed by passenger ship acci-dents that happen from time to time.
The design of escape routes in passenger vessels should enable passengers and crew members to leave the hazardous areas safely if need arises to evacuate the ship.
It is very important problem to shortening the evacuation process, and the methods of evacuation routes signing should be still improved. In addition to directing the evacuation by crew member also the symbols of evacuation signs should be fixed to human perception and properly distributed at evac-uation routes. Attention should be paid for rather usual problem of disturbing the visibility of evacua-tion signs by neighboring of advertising and other boards which are not connected with evacuation
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Recenzent: dr hab. inż. Marek Dzida, prof. PG Politechnika Gdańska
