MSC Circ 1033 and 1283
SOLAS regulations specifies the maximum time (currently set at 30 minutes) that it should take to prepare and launch the lifeboats and life rafts from a passenger ship, once the passengers are actually assembled,. However, there were no specific regulations on the complete timeframe for the total vessel evacuation process. This has now been addressed by the IMO “Guidelines for a Simplified Evacuation Analysis for New and Existing Passenger Ships” covered by MSC Circ 1033 and its successor MSC Circ 1238. Since they are still only IMO guidelines it is the down to individual states to adopt all or part of the guidelines into national regulation or to keep them as just ‘guidelines.’
The IMO Maritime Safety Committee initially approved MSC/Circ. 909 for evacuation analysis of ro-ro passenger ships in May 1999 and in June 2001 MSC/Circ 1001 as an interim guidelines for a simplified evacuation analysis of high-speed passenger craft, following a recommendation from its sub-committee on Fire Protection. Both of these were guidelines were primarily driven by considerations of structural fire protection times and on board a vessel.
Based on these earlier guidelines the Fire Protection sub-committee was also asked to develop further guidelines for passenger ship evacuations in general. This resulted in MSC Circ 1033 a “Guidelines for a Simplified Evacuation Analysis for New and Existing Passenger Ships” but this was always intended as an interim guideline. Passengers will not necessarily respond immediately to a call to assemble during an emergency. This time lag between the announcement and passengers starting to move off to the assembly station is known as the response time and is a key to component of the evacuation process. There was little or no data relating to passenger response times in maritime environments so much of the data used for these guidelines was derived land based building measurements. While there are many parallels there are also a number of operational differences for passenger ship evacuations. The committee recognised that there was a need for data and information to help further validate and develop these guidelines.
The FIRE EXIT project undertook sea trials on ship evacuation response times on board a ro-ro ferry Grimaldi during a voyage between the Port of Rome and Barcelona April 2005. While the data collected from this trail was limited it did clearly demonstrated that the response time data used in MSC Circ 1033 was not sufficiently detailed to provide a suitable basis for the modelling or validating evacuation simulation software. The FIRE EXIT sea trial data relating to response times was submitted to IMO and incorporated within the new analysis protocol MCS Cir 1238.
The guidelines call for the total passenger ships evacuation times to be assessed during the design phase. The guidelines recommending the maximum allowable total passenger ship evacuation time to be in the range of 60 to 80 minutes based on the following:
- 60 minutes should apply to ships having no more than three main vertical (fire) zones: and
- 80 minutes applying to ships having more than three main vertical (fire) zones.
It specifies a minimum of four passenger evacuation cases scenarios to be considered. The primary case covers modelling the full passenger ship evacuation at the night and during the day. A secondary cases involving modelling just one of the main vertical fire zones but assuming that only 50% of the stairways are available or than an additional 50% of the passengers from a neighbouring zone are forced to move into the zone to proceed to the assembly point. These are also to be modelled at night and during the day.
The guidelines provide for the possibility of undertaking either a simplified or a more advanced passenger ship evacuation analysis method. The guidelines recognised that the simplified “hydraulic” method, which treats passengers like particles moving in a liquid flowing through a pipe, can be useful in estimating total evacuation times during early ship design but is limited particularly as vessel complexity increases. The simplified method assumes
- all passengers and crew will begin the evacuation at the same time and will not hinder each other.
- passengers and crew will evacuate via the main escape routes
- walking speeds depend on the density of people, flow is only in one direction and there is no overtaking
- passenger load and initial distribution are based on the safety system on chapter II-2 of SOLAS is known as Fire Safety System Code (FSS code)
- counter-flow is accounted for by a correction factor
- effects of ship motion, passenger age and mobility, unavailability of corridors, effects of smoke, etc., are accounted for by a correction and safety factor
The second more advanced methods based on computer simulations seek to model the passengers and crew as unique individuals with specific capabilities and response times. The simulations assume that the crew will immediately be at the evacuation duty stations ready to assist the passengers and that the passengers follow the signage systems and crew instructions. The guidelines provide response time distributions, passenger sex and age distribution, walking speeds on flat terrain(including a statistical distribution) and on stairs. The MSC Circ.1238 guidelines still do not take account of family group behaviour, effects of heat and smoke, effect of ship motion, heel and trim on the passenger/crew performance. The guidelines acknowledge the need for more information and data on full-scale tests on human behaviour during ship evacuations, particularly for any future upgrading of the present guidelines. The guidelines also recognises that software verification is an on-going activity but suggest a number of simple test cases for checking the evacuation simulation until there is sufficient reliable data generated from evacuation demonstration to undertake quantitative verification of the software.
The SAFEGUARD research project aims to acquire a large body of real ship based data on passenger response times and assembly. The data from these trials along will be submitted to IMO and it is hoped that it will be used to help further improve MSC Circ 1238. The results for this project will be presented at a passenger evacuation seminar on 30 November 2012 in London