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Barriers and Fencing
Barriers and Fencing

This chapter is sponsored by Framelock Barriers

Precis

(Revised 20 November 2017)

The entertainment uses fences and barriers in roughly three areas: Perimeter fencing, crowd access management and crowd control. It is critical that the use of barriers and fencing does not present greater risks than those which they are intended to control. There are many documented scenarios where barriers and fencing have failed through incorrect use. In determining the type of fence or barrier for a certain application must consider all load aspects the structure will be exposed to. The load could take the form of wind, crowd pressure, vehicle or animals, etc.

16.1 Referenced documents:

WHS Regulation 2011

AS 4687-2007 – Temporary fencing and hoardings

AS/NZS 1170.0:2002 – Structural design actions – General principles

AS 1742.10-2009 – Manual of uniform traffic control devices – Pedestrian control and protection

International Standard BS EN 13200-3:2005 (Spectator Facilities) Annex A

Guidelines for concerts, events and organised gatherings WA Department of Health

Temporary Demountable Structures – The Institution of Structural Engineers Fourth Edition April 2017

16.2 Definitions

16.2.1 Types of fence or barrier

16.2.1.a Temporary fencing

Temporary fencing is a self-supporting and modular system, which is interlocking and portable. The different systems vary in height and width. The panels are sheeted with a combination of synthetic material, chain link fabric and welded mesh. All temporary fence systems are supported with a base plate, block, counterweight or other fixing methods.

16.2.1.b Temporary hoarding

Temporary hoarding is a self-supporting system sheeted with timber plywood, coated steel or sturdy synthetic material. The different systems vary in height and width. All temporary hoarding systems are supported with a base plate, block, counterweight or other fixing methods.

16.2.1.c Barrier

Any element of an entertainment venue or site, permanent or temporary, intended to retain, stop or guide people.

16.3 Risk Assessment

Although the requirement for fencing and barriers will often come as a result of the overall event risk assessment, it is important to carefully consider all the fencing options and ensure the best option is chosen.

Incorrect use of a barrier / fencing product for a location or circumstances could cause injury or harm. The risk assessment should be prepared in conjunction with the crowd management plan and consider crowd numbers, demography, expected behaviours etc. It should also consider the ‘lay of the land’, surrounding areas, usual use of the site if a temporary site and expected weather patterns.

16.4 Perimeter Fence

The perimeter fence has a number of functions, each should be considered when determining the most appropriate type of fence. The function may also change throughout the event which should be taken into consideration. There may also be licensing requirements that dictate a certain type of fence to be used. For a basic delineation of an area either Crowd Control Barrier (CCB) or even ‘rope & stanchion’ could be suitable. For a separation between general public and worksite areas CCB’s would be preferred over ‘R&S’ simply based on rigidity and less ‘temper’ prone. And finally, when access control and or visibility is a concern then 2 metre high options such as chain-link ‘cyclone fencing’ (mesh panels) may be the preferred option.

16.4.1 Certification

Whichever type of fence you use, it will need to be certified and have been tested against the conditions set-out in AS 4687-2007. In section 4 the Standard sets out the tests to determine the suitability of a temporary fence or hoarding:

  • Simulated Climbing test
  • Impact test
  • Infill Aperture test
  • Wind Force Overturning test

All tests may be conducted on a single panel, a number of linked panels and linked panels with additional bracing. For the test certificate to be valid, the same configuration as used in the tests must be used on site.

Where the temporary fence is to be covered in shadecloth or any other material, this must be specifically noted in the Wind Force Overturning test. Most fence panels will require additional bracing if anything is to be attached to the fence.

Note that even CCB with a fabric cover will be effected by wind and could move or blow-over causing injury or damage.

16.4.2 Exits

Whichever type of perimeter fence is selected, consideration must be given to emergency exits in addition to normal ingress and egress.

 

NCC D1.6 Exits to be provided
(c) if the storey, mezzanine or open spectator stand accommodates more than 100 persons but not more than 200 persons, the aggregate unobstructed width, except for doorways, must be not less than—
(i) 1 m plus 250 mm for each 25 persons (or part) in excess of 100; or
(ii) 1.8 m in a passageway, corridor or ramp normally used for the transportation of patients in beds within a treatment area or ward area; and
(d) if the storey, mezzanine or open spectator stand accommodates more than 200 persons, the aggregate unobstructed width, except for doorways, must be increased to—
(i) 2 m plus 500 mm for every 60 persons (or part) in excess of 200 persons if egress involves a change in floor level by a stairway or ramp with a gradient steeper than 1 in 12; or
(ii) in any other case, 2 m plus 500 mm for every 75 persons (or part) in excess of 200; and
(e) in an open spectator stand which accommodates more than 2000 persons, the aggregate unobstructed width, except for doorways, must be increased to 17 m plus a width (in metres) equal to the number in excess of 2000 divided by 600; and
(f) the unobstructed width of a doorway must be not less than—
(i) the unobstructed width of each exit provided to comply with (b), (c), (d) or (e), minus 250 mm;

16.4.2.a Checklist for Exit Locations and Sizes

Patrons must not be contained in an area for longer than six (6) minutes at a density closer than 4 people/m2.

Queues should flow at a rate no slower than 0.5m per second.

Each separate area must have a minimum of two (2) exits located at opposite locations or at least spread as far apart as practicable. Exits must be open spaces or gates hung to swing in the direction of egress.

NOTE: It is unacceptable to have sliding doors, fencing panels or fences that require dismantling.

Generally exits are required to be attended at all times to prevent them being used for unauthorised access.

It is recommended that for large outdoor events, exits are provided at either side of ‘mosh’ pits.

Each exit should be clearly sign posted and numbered to allow easy identification for staff, patrons and emergency services in the event of an emergency.

16.4.2.b Number of exits and widths

The National Construction Code, Section D1.6 (c)(d)(e) sets out the number of required exits from a building.

For NSW, Table H102.4 sets out the requirements for egress from temporary structures.

16.5 Crowd access management

Access management barriers are typically used to queue people for access or F&B and other areas without an expectation of crowd surges or a requirement to restrain access. Typically this application would use ‘rope & stanchion’ or Tensa barrier type fencing to guide people as required.

Where large crowds are expected and more strict control is required, CCB or even Plastic Longitudinal Barriers (AKA water-filled barriers) can be considered. Note that if any barriers are used in areas that are designated exits, see above, then they must be able to be cleared quickly without becoming a trip hazard. Unless securely bolted down, stanchions should not be left in an egress path. CCB and empty plastic barriers should be moved away from any egress area as soon as practicable.

16.5.1 External barriers

Where queueing outside the event site is expected and queueing may be on public roads or alongside moving traffic, a barrier may be required for the safety of the public. Barriers used in such occasions should meet the requirements of AS1742.10:2009.

16.6 Crowd Control barriers

This application of barriers does take crowd pressure into consideration and are normally found in front of a stage, around Front of House positions or anywhere else where pressure from crowds can reasonably be expected.

16.6.1 Front of stage barrier

The layout and arrangement of the front-of-stage barrier is a function of stage height, side-stage positions, security arrangements and the venue geometry. Front-of-stage barriers in use in the entertainment industry are purpose-built modular units. They need to be highly specialised barrier panels that not only can withstand crowd pressure but will also allow safety marshals (event security) to extract people from the crowd easily and safely by lifting them over the barrier if they are in difficulty or at risk of injury or harm. Barriers constructed from scaffold or other none purpose build materials should not be used. The high crowd density directly in front of a stage can lead to the risk of asphyxiation or chest injuries. The recommended height of a Front of Stage barrier is between 1.05m – 1.22m. The barrier should not have sharp edges, gaps or any other elements that could cause injury. The barriers should have a step on the stage side to allow security, marshals and paramedics easy access to people on the other side of the barrier. It also gives security an elevated position to view and monitor the crowd.

16.6.1.a Design considerations for the front of stage barrier

Based on Table 12 – Guidelines for concerts, events and organised gatherings WA Department of Health

  • Must be able to withstand a load of 7kilo newtons/metre right angle load.
  • Barriers need to be at an appropriate height on the audience side to prevent thoracic compression.
  • The preferred height of the stage barrier above the surface on which the audience stands is 1.2 metres, but should be no less than 1.1 metres.
  • In areas subjected to extreme pressure, consideration should be given to restricting patrons who are of short height or at least advising them of the inherent danger of the location so that they may make an informed decision.
  • Must have a dead front with no sharp protrusions.
  • No finger or hand entrapments.
  • Must provide an elevated platform for crowd controllers.
  • Must have a curved or padded top.
  • Allow vision through the barrier to ground level.
  • For small, low-risk events a straight barrier is suitable.

16.6.2 Design loading considerations

The industry standard ‘Mojo’ type barriers all rely on the weight of the crowd to provide the kentledge that stops the barrier from overturning. Care should be taken regarding this assumption in terms of the number of people required to generate the deadload. A children’s show, for example, may fall well short of the expected weight. It will be advisable to have the barrier design reviewed and confirmed by a qualified engineer based on the barrier engineering details and expected crowd demographics.

Other consideration are the surface on which the barrier is placed. The coefficient of friction should be considered in the risk assessment

16.6.3 Installation and inspection

The front of stage barrier is a critical ‘first line of defence’ and likely to be exposed to the design loadings. It is usually the last thing to go in but ample time should be allowed for the barrier to be constructed in accordance with the manufacturers’ instructions. Equally important are the checks upon completion to make sure that all bolts are properly fitted, there are no gaps where fingers or toes could get caught and the whole structure is solid without any movement. The latter is extremely important on ‘greenfield’ site where the ground may not be perfectly level.

16.6.4 Position

The position of the barrier must be discussed between the event safety marshals / security, the site paramedics and the touring security. The band, through their production and security staff, will have demands about the position of the barrier. This must be incorporated to avoid lengthy arguments on the day but should never compromise the work area required by the safety marshals and paramedics.

There is an increasing need for video camera’s, usually on dolly’s and tracks, and photographers to operate between the barrier and the stage. This space must not reduce the work area required for marshals and paramedics.

16.6.5 Convex shaped barriers

Convex barriers provide the following advantages:

  • It dissipates crowd surges away from the centre of the stage.
  • It assists means of escape.
  • It provides a wider front row sightline.
  • It improves security by placing a greater distance between the downstage edge and the
  • barrier making it difficult for fans to reach the stage.
  • It can provide a wider area for crowd controllers and first aiders to operate within the ‘pit’.

Concave shaped barriers must be avoided at all times as they can increase the risk of crowd based entrapment.

16.6.6 Multiple barrier arrangements

Multiple, or zoned, barriers arrangements are becoming more common place in contemporary concerts. Both the elaborate stage designs incorporating thrusts or satellite stages and additional crowd management requirements have seen an increase in multiple barriers. Multiple and odd-shaped barriers need to be considered carefully, not only in pressure density but also in ingress, milling, egress and emergency escape.

With complex barrier systems the evacuation procedures and time required to clear the area should be calculated and revised if they exceed expectations. Zoned barrier arrangements can reduce crowd surges and as a result reduce the risk and impact of crowd crushes. However, it must be recognised that moving a hazard away from the main area does not remove the hazard. Areas that may not receive the level of spill light from the stage due to their location could introduce new risks and hazards.