Progressive horizontal evacuation

Progressive horizontal evacuation is an evacuation strategy in which occupants move first to an adjacent protected area on the same level, with further relocation if the threat continues to develop. The International Fire Engineering Guidelines describe this sequence for hospitals: nursing staff move patients to a neighbouring smoke zone or fire compartment before any wider evacuation becomes necessary. The initial destination is therefore an intermediate protected location within the building, rather than necessarily the final external assembly point.

The strategy connects assisted movement with the protection provided by the receiving area. Its performance depends on occupant needs, available staff, the route and the continuing fire conditions. As an evacuation strategy, it requires both physical provisions and management arrangements. Moving occupants across a boundary is only one stage in maintaining their safety.

Initial relocation and subsequent stages

The Guidelines describe hospitals as an example of staged evacuation. Patients nearest the fire and most at risk are moved first. Staff initially relocate them horizontally to an adjoining smoke zone or fire compartment. Further movement, or evacuation of additional compartments and floors, follows if the fire threat continues to develop.

Patients may first move to an adjacent protected area, with further relocation if the threat develops. Based on ABCB (2005), p. 2.8-2.

This sequence differs from immediately assigning every occupant to a route outside. It allows the first movement task to be defined around an adjacent destination. The assessment must still state the extent and nature of the intended movement. The Guidelines require those decisions to be established in the fire engineering brief.

Phased evacuation is a broader staged approach that can also involve releasing occupants from different floors. Progressive horizontal relocation concerns the initial transfer across the same level. The hospital example combines staging with this particular movement direction. The timing and escalation arrangements must follow the actual strategy, rather than the label alone.

A stay-put strategy instead concerns arrangements in which occupants remain in their present location under the applicable protection assumptions. The Guidelines discuss protection in place separately from moving patients into another zone. These approaches cannot be treated as identical because both avoid immediate total discharge. Their initial occupant actions and destinations differ.

The receiving area and the route

Fire compartmentation provides one form of boundary used in the hospital relocation sequence. The Guidelines also refer to adjacent smoke zones. The particular receiving area must therefore be identified in the assessment. Describing a destination merely as another room does not establish that it fulfils the intended protected role.

The ABCB data sheets identify horizontal exits and protected areas among provisions relevant to occupants with limited mobility. They also require consideration of circulation space and route characteristics. These provisions connect the receiving area to the means of reaching it. The movement task cannot be assessed solely by the existence of a boundary on a plan.

Conditions must be examined along the route and in the enclosures traversed. The data sheets require checks for exposure to untenable conditions during evacuation. A short travel distance does not establish that the movement is acceptable. Its timing must be compared with the conditions expected while patients and staff are present.

The destination is also an assumption in the movement estimate. New Zealand's C/VM2 second edition explicitly ties its hospital transfer allowance to an adjacent enclosure being available. Its commentary states that a longer pre-travel allowance may be needed where this is not the case. The assumed destination therefore influences the calculated timing directly.

Patients, staff and assisted movement

Evacuation of people with disabilities requires attention to the assistance and route needed by the relevant population. The ABCB data sheets include temporary and permanent limitations affecting recognition, response and movement. Hospital patients can also have clinical needs that vary between wards. A single independent walking speed cannot describe all these evacuation tasks.

The International Fire Engineering Guidelines distinguish the role of staff response from the time required to move patients. They identify patient type, including intensive care and surgery, as relevant to movement. The group controlling one part of the timeline may differ from that controlling another. Staff availability and patient characteristics therefore require separate consideration.

Staff may need to prepare a patient, transport that patient and return for another. The 2025 C/VM2 method explicitly includes those activities within its stated hospital allowance. Treating it as walking time alone would misrepresent the work assigned to each team. The cycle describes repeated assistance, rather than an unbroken stream of independently mobile occupants.

The cited allowance includes preparation, patient transport and staff return, rather than walking alone. Based on MBIE (2025), p. 30.

The number of available teams can consequently affect the relocation sequence. Availability means that the staff can undertake the assigned movement, not simply that they appear in the building's total staffing count. The Guidelines identify reduced night staffing as relevant in hospital scenarios. The analysis needs the staff and patient circumstances associated with the scenario being examined.

A source-specific timing allowance

New Zealand C/VM2, second edition dated 28 July 2025, gives a hospital and rest-home allowance for occupants in the enclosure of fire origin. It allows 60 seconds for staff response, followed by 120 seconds per patient for each two-person staff team. These are assumptions within that verification method. They are not universal measured transfer times for all patients and hospitals.

The table's note includes preparation, transport to the next adjacent firecell and staff return. It identifies three teams of two staff as a realistic maximum for the assumed shuttling operation. This qualification prevents unlimited multiplication of parallel teams within that method. It does not establish that every ward actually has those staff available.

The same table addresses occupants who cannot be moved because of a procedure or other factors. Its allowance then depends on the specific procedural requirement or 1,800 seconds, whichever is greater. This is a separate condition from the ordinary patient-transfer allowance. Applying the shorter cycle to such a patient would omit the source's stated qualification.

Although the table calls these values pre-travel activity times, its hospital note includes physical transfer and return. That terminology matters when integrating it with another model. Adding a second full transport period for the same activity would count that movement twice. The activities represented by each time allowance must be mapped before the periods are combined.

Worked illustration of team availability

Consider six illustrative patients who can use the stated adjacent-firecell transfer arrangement. Assume all staff teams become ready after the same 60-second response period. Each team handles one patient at a time using the source's 120-second cycle allowance. The example holds patient needs and cycle duration constant to isolate the effect of team availability.

With one two-person team, six successive allowances give 720 seconds after the response period. The combined allowance is therefore 780 seconds. With two teams working concurrently and equally sharing the patients, each team handles three patients. Three cycles plus the initial response period give 420 seconds.

Ideal concurrent teams change the illustrative total allowance for six patients. Based on MBIE (2025), p. 30.

With three concurrent teams, each handles two patients. The corresponding allowance is 60 seconds plus two periods of 120 seconds, giving 300 seconds. These derived values apply the selected ideal scheduling assumptions. They are not observations of patient movement or proof that adding staff always produces the same improvement.

The calculation retains the source's full return allowance within every cycle, including the last. It should therefore be read as an application of its tabulated allowances, rather than an exact prediction of the last patient's arrival. Clinical preparation, unequal tasks or unavailable receiving space can change the actual sequence. Those circumstances require their own justified inputs.

Management and limits of the strategy

The ABCB requires the fire safety strategy to cover all occupants and the management arrangements needed to keep it effective. Its management definition includes organisation, communications, procedures, disability provisions, training and drills. These provisions are directly relevant when staff must relocate patients repeatedly. The physical compartment layout and the staffing plan must support the same intended sequence.

The initial relocation does not determine how long the receiving area remains suitable. The Guidelines make further movement conditional on the developing threat. The assessment must therefore preserve the distinction between completing one transfer and completing the whole protective strategy. A successful first stage does not remove the need for the later arrangements specified for that scenario.

The supplied sources describe the sequence and selected timing assumptions but do not provide a complete hospital relocation design method. They do not establish universal compartment capacities, protection durations, clinical preparation times or escalation thresholds. Those details depend on the relevant project and dedicated evidence. The cited numerical example should remain confined to the assumptions actually described.

References

• Australian Building Codes Board. (2005). International fire engineering guidelines (2005 ed.).
• Australian Building Codes Board. (2020a). Handbook: Fire Safety Verification Method (Version 1.1).
• Australian Building Codes Board. (2020b). Data sheets: Fire Safety Verification Method (Version 1.1).
• Ministry of Business, Innovation and Employment. (2025). C/VM2: Verification method for the New Zealand Building Code clauses C1–C6 protection from fire (2nd ed., 28 July 2025).