The steps in the evacuation analysis are:
3.1 Description of the system
.1 Identification of assembly stations.
.2 Identification of embarkation stations, MES and survival craft.
.3 Description of the evacuation procedure including the role of the crew.
.4 Identification of groups and their escape route.
3.2 Assumptions
Thismethodforestimatingevacuationtimeisbasicinnatureand,therefore,commonevacuation analysis assumptions should be made as follows:
.1 passengers and crew should carry out the evacuation in a sequence of groups according to the evacuation procedure;
.2 passengers and crew will evacuate via the primary escape route;
.3 walkingspeeddependsonthetypeofescapefacility,assumingthattheflowisonly
in the direction of the escape route, and that there is no overtaking;
.4 passengers'disabilitiesormedicalconditionsthatwillseverelyhampertheirability
to keep up with the flow are neglected (see paragraph 3.2.8.1 below);
.5 passenger load is assumed to be 100% (full load);
.6 full availability ofescape arrangements is considered;
.7 people can move unhindered;
.8 theallowableevacuationtimeaspersection4.8.1ofthe2000HSCCodeisgiven by SFP - 7 (min), where:
3
.8.1 divisionby3accountsforthesafetyfactor,whichincludespassengers'ages anddisabilities,restrictedvisibilityduetosmoke,effectsofwavesandcraft motionsondeployment,travelandembarkationtimeandofviolationstothe evacuation procedure;
.8.2 subtractionof7minaccountsforinitialdetectionandextinguishingaction (section 4.8.1 of the 2000 HSC Code); and
.8.3 for category B craft, the passenger awareness time, the time needed for passengers to reach assembly stations and the time needed for manning emergencystationsisincludedinthe7mintime(seesection4.8ofthe2000
HSC Code);
.9 astheevacuationprocedureisdesignedtocarryoutevacuationundercontrolled conditions (section 4.8.1 of the 2000 HSC Code), no counter flow takes place; and
.10 whenusingtable3.6itisassumedthatatthebeginningoftheevacuation,passengers are located at a distance not greater than two decks fromthe embarkation station.
3.3 Scenarios to be considered
3.3.1 ForthepurposeofcalculatingtheevacuationtimeincategoryAcraft,passengersshouldbe assumed to be distributed in a normal voyage configuration (section 4.8.4.1 of the 2000 HSC Code).
3.3.2 ForthepurposeofcalculatingtheevacuationtimeincategoryBcraft,passengersandthe crewshouldbeassumedtobedistributedamongassemblystationsandbereadyforembarkation (section 4.8.4.2 of the 2000 HSC Code).
3.4 Performance standards
3.4.1 Thefollowingtwoperformancestandardsshouldbecompliedwithforcalculatingtheoverall evacuation time:
tM + tE < SFP - 7 (3.4.1.1)
3
tI + tE < SFP - 7 (3.4.1.2)
3
3.4.2 Both performance standards are derived fromsection 4.8.1 of the 2000HSC Code.
3.5 Calculation of tE and tM
3.5.1 ThevaluesoftE andtM shouldbecalculatedseparatelybasedonanappropriatecombination of the following documented and independently witnessed trials as is acceptable to the Administration but which may be subject to verification trials:
.1 type approval trials1 for any inflatable liferafts and marine evacuation systems used for the evacuation of the craft, the relevant deployment and embarkation times being increased by factors of 1.3 and 1.14, respectively; and
.2 full scale shipboard trials on closely similar craft and evacuation systems.
3.5.2 Safetyfactorson tE and tM areaccountedforbydividingby3inperformancestandards formulae (3.4.1.1) and (3.4.1.2).
3.6 Calculation of tI
3.6.1 Parameters to be considered:
.1 clear width, Wc , is:
.1 measured off the handrail(s) for corridors and stairways;
.2 the actual passage width of a door in its fully open position;
.3 the space between the fixed seats for aisles in public spaces; and
.4 thespacebetweenthemostintrudingportionsoftheseats(whenunoccupied)
in a row of seats in public spaces;
.2 speedofpersons,S(m/s)isthespeedofevacueesalongtheescaperoute(table3.6
provides the values of S which should be used for the analysis);
.3 specificflowofpersons,Fs (p/(m/s)),isthenumberofevacuatingpersonspasta pointin theescaperouteperunittimeperunitofclearwidthWc (table3.6provides the values of Fs which should be used for the analysis).
Table3.6*
Type of facility | Speed of persons S (m/s) | Specific flow Fs (p/(m/s)) |
Stairs (down) | 0.55 | 1.1 |
Stairs (up) | 0.44 | 0.88 |
Corridors, doorways | 0.67 | 1.3 |
.4 calculatedflowofpersons,Fc (p/s),isthepredictednumberofpersonspassinga
particular point in an escape route per unit time. It is obtained from:
Fc = Fs ¿Wc (3.6.1.4)
.5 flowtime, tF (s),isthetotaltimeneededforagroupofNpersonstomovepasta point in the egress system. It is calculated as:
tF = N / Fc (3.6.1.5)
.6 walking time, tw (s), is the total time needed for a person to cover the distance between the assembly station and the embarkation station.
3.6.2 Transitions
Transitionsarethosepointsintheegresssystemwherethetypeofaroutechanges(e.g.froma corridor to a stairway) where routes merge or branch out.
3.6.3 Procedure for calculation of tI is as follows:
.1 Groups of people:
Forthepurposesofevacuation,thetotalnumberofpersonsonboardisbrokendown intooneormoregroupsofpeople. Itshouldbeassumedthatallpersonsinagroup carryouttheevacuationatthesametime,alongthesamerouteandtowardsthesame embarkationstation.Thenumberofpersonsineachgroup,thenumberofgroupsand theembarkationstationassignedtoeachgroupshouldbeinaccordancewiththe evacuation procedure.
.2 Schematic representation:
Theescaperoutesfromassemblystationstoembarkationstationsarerepresentedasa hydraulicnetwork,wherethepipesarethecorridorsandstairways,thevalvesarethe doors and restrictions in general.
.3 For each foreseen group of people:
.1 Thewalkingtime,tw,iscalculatedbyusingthespeedofpersonsspecifiedin table3.6andthedistancebetweenthepertinentassemblyandembarkation stations.
.2 Theflowtime,tF,ofeachportionoftheescaperouteiscalculatedusingthe specificflowFs fromtable3.6andtheappropriateclearwidthofthatportion
of escape route. The total flow time is the largest value obtained.
.3 Thetraveltimeisobtainedasthesumofthewalkingtimeandthetotal flow time.
3.6.4 Ideal travel time tI
Calculationsasperparagraph3.6.3.3shouldberepeatedforeachforeseengroupofpeople. The highestresultingtraveltimeisthentakenastheidealtraveltimeforuseinperformancestandardin paragraph 3.4.
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1 RefertotheRevisedrecommendationontestingoflife-savingappliances,andinparticularthetimesmeasuredin accordancewith5.17.3.3and12.6.1ofthatrecommendation(asadoptedbyresolutionMSC.81(70)).
* Dataderivedfromland-basedstairs,corridorsanddoorsincivilbuildings,andareextractedfromthepublication “
SFPEFireProtectionEngineeringHandbook,2ndeditionNFPA1995”.