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Fire Safety Considerations For Automated Vehicle Parking Systems

11 July 2022

By Haydn Lewis, Fire Engineering Manager & Viktor Yarchuk, Fire Safety Engineer

What are Automated Vehicle Parking Systems (AVPS)?

Automated Vehicle Parking Systems (AVPS) are becoming increasingly common and popular in all building classifications across Australia. AVPS can vary from simple two level car stackers to fully automated systems with capacity for hundreds of vehicles. They are incorporated to increase the value of a development through maximising usable space and assisting to satisfy applicable planning requirements.

How does the NCC address AVPS?

Whilst becoming more frequent, to date the National Construction Code is yet to include any specific prescriptive Deemed-to-Satisfy (DTS) provisions related to AVPS, including car stackers. It is common for the Fire Brigade and Certifiers to categorise AVPS as special hazard items under Clauses E1.10 and E2.3, requiring each proposal to be assessed on its own merits. As a result of this, we commonly see overly conservative interpretations by approval authorities as well as limited design, both of which result in less than optimum project outcomes.

SGA Fire, A Jensen Hughes Company, has experience in developing solutions that are offered with great confidence to our clients and industry partners. We treat the subject of AVPS holistically, and will provide advice and guidance to the design team.

What are the challenges?

Automated Vehicle Parking Systems result in vehicles being stored both horizontally and vertically which increases the risk of fire spread between vehicles and the overall peak fire size (Heat Release Rate), potentially posing greater challenges to occupants seeking egress and the fire brigade entering the building for fire intervention activities. Large fully automated AVPS also have the potential to cause significant challenges concerning how fire brigade personnel approach the seat of the fire.

How can they be addressed?

Depending upon the size of the AVPS a variety of different fire safety measures can be considered.

The Australasian Fire and Emergency Service Authorities Council Limited (AFAC) has produced a guideline detailing the fire brigade intervention considerations within AVPS which are often utilised as a starting point for discussions amongst the design team [1].

The following are the list of measures that could be expected in a large fully automated AVPS:

  • Provision of sprinkler coverage to the car park, with additional heads located at each corner of each car within the AVPS.
  • Provision of smoke exhaust system serving the AVPS.
  • Signage to inform of the requirements for fire brigade intervention.
  • AVPS programmed to shutdown upon detection of fire and not automatically start-up upon fire panel reset.
  • Consideration of access routes throughout the AVPS.

Smaller applications, such as car stackers, would likely require a simplified set of fire safety measures than those listed above which are considered on a case-by-case basis.

Do we really need sprinklers?

This is a very common query we often receive for car stacker proposals, and yes a sprinkler system with additional ‘in-rack’ sprinkler heads are required (for all but the smallest installations).

The fundamental buoyant properties of flames result in a more rapid vertical fire spread than horizontal fire spread. This rapid spread and increase to peak Heat Release Rate provide a higher exposure condition than would ordinarily be experienced within a DTS car park.

Fire tests undertaken by BRE [2, 3] have quantified the benefit that in-rack sprinkler heads have on the potential for fire to spread vertically between stacked vehicles. Without suppression systems, these tests showed that rapid fire spread occurred fully engulfing the upper car within 10 minutes of ignition of the lower car. When a similar test was undertaken featuring in rack suppression, the test was run for 100 minutes with no fire spread and limited damage to the underside of the upper vehicle.

It is for this reason that sprinkler systems are often specified to serve AVPS within car parks which may not otherwise require them under the DTS measures of the BCA.

Photographs that visually demonstrate the difference between non-sprinklered tests

Top Photo – Test in progress (10 min 10 s from ignition) ~ Bottom Photo – Test in progress (13 min 19s from ignition)

Sources

Images

  1. Top Photo – BRE, Fire Spread in Car Parks (ref. BD2552), December 2010, Photograph 2.20.5: Test 11 – Test in progress Two cars, located on a “stacker” frame; 10 min 10secs from ignition, p.92, viewed 29 June 2022, <https://www.ife.org.uk/write/MediaUploads/Incident%20directory/Monica%20Wills%20House%20-%202002/BRE_DCLG_BD2552_Fire_Spread_in_Car_Parks_2010.pdf>
  2. Bottom Photo – BRE Global, Sprinkler Protected Car Stacker Fire Test, ref. 256618, dated 11 December 2009, Figure 9 – Test in Progress; 13 minutes 19 seconds from ignition, p.16, viewed 29 June 2022, <https://www.bre.co.uk/filelibrary/pdf/rpts/BRE_Global_Client_Report_no_signatures.pdf>

References

  1. Australasian Fire and Emergency Services Authorities Council. (2016) Emergency Medical Response (AFAC Publication No. 3044). East Melbourne, Vic: Australia. AFAC Ltd;
  2. BRE, Fire Spread In Car Parks (ref. BD2552), Test 11 Two cars, located on a “stacker” frame, December 2010; and
  3. BRE Global, Sprinkler Protected Car Stacker Fire Test, ref. 256618, dated 11 December 2009.

What Next?

If you are a developer, architect, or industry professional planning to incorporate an AVPS of any size in your next project please do not hesitate to get in touch with our fire engineering experts and talk through the specifics of how we can add value to your design team.

Contact us on 02 9411 5360 or at BCALogic.info@jensenhughes.com