Bomb Blast DoorsA specifier’s guidance document

It is an unfortunate fact of life that heightened levels of terrorism have made public places an easy target. On the UK mainland, crowded places such as public transport systems and their associated infrastructure, from airports through to train stations, have been favoured targets. The response of governments across the world has been to devise new rules designed to protect people and places from such attacks.

Inevitably, this state of heightened security has placed civil engineers, architects, specifiers, facilities managers and heads of security at the forefront of the drive to make public buildings and spaces safer.

The big issue is striking the balance between security and usability. How can people be kept safe without impacting their access to a building and what impact will counter-terrorism measures have on access for the disabled or those with other impairments? What is the potential effect of counter-terrorist measures on the overall look of a building and its ability to seamlessly integrate into its environment?

These are all questions which those responsible for the design, upkeep and construction of buildings regularly ask and nowhere are these challenges of balancing security with accessibility and aesthetics more apparent than with door systems and door security.

Doors and access systems play a major role in both security and usability. The good news is that modern door systems can look good, allow the free movement of people and, crucially, act as a barrier to terrorist activity.

This guide is designed to offer those responsible for door systems during construction, specfication or ongoing use, an overview of the regulatory environment that is now in place and the different products, including enhanced security doors and bomb blast doors, which are available.

Further information about Dor-O-Matic bomb blast doors and Ingersoll Rand’s RIBA approved CPD programmes on bomb blast entrances can be found at:

www.security.ingersollrand.com/bombblast

Stephen Badgery

Dip GAI, Dip FD

Ingersoll Rand Security Technologies

Foreword

The problem of keeping people safe during heightened levels of terrorism

There are two key documents, both published by the Department of Communities and Local Government, which can help those involved in the specification of bomb blast doors understand the decision making process within local authority planning departments in relation to counter-terrorism.

Safer Places: The planning system and crime prevention (April 2004)

Safer Places does not set out new policy or legal requirements, but it does provide advice on counter-terrorism protective measures. (Note: it is relevant to England only, as planning functions are devolved in Scotland, Wales and Northern Ireland). The thinking behind Safer Places is that the most effective form of counter-terrorism is to consider measures as early as possible in the planning process in order for them to be fit for purpose, cost effective and unobtrusive.

Understanding the planning process

Key documents in the local authority decision making process

Crowded Places: The Planning System and Counter Terrorism (March 2010)

Crowded Places is a supplementary publication to Safer Places which offers a useful definition of a crowded place. A crowded place is defined as:

A crowded place is a location or environment to which members of the public have access that may be considered potentially liable to terrorist attack by virtue of its crowd density.

Crowded places will be found in a wide range of locations, including sports stadia, pubs/clubs/bars, shopping centres/high streets, visitor attractions, cinemas and theatres, commercial centres.

Crowded places can also include the public realm - open spaces such as parks and squares.

In each case a crowded place will not necessarily be crowded at all times – crowd densities may vary during the day/night and may be temporary as in the case of sporting events or open air festivals.

Crowded Places: The Planning System and Counter-TerrorismJanuary 2012

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afer Places

The Planning System

and Crim

e Prevention

This good practice guide sets out how the planning system is able to deliver well-designed and safe places. It challenges all those involved in the design and layout of new development to think about the mostappropriate crime reduction measures without compromising the quality of the localenvironment. In doing so, it emphasises theimportance of designing to suit the localcontext. This guide builds on and complementsGovernment urban design and crime reductionobjectives and guidance, including Secured By Design.

The Customer Services DepartmentThomas Telford LimitedUnit I/KPaddock Wood Distribution CentrePaddock WoodTonbridge TN12 6UU

Tel: 020 7665 2464Fax: 020 7665 2245

The challenge for specifiers is to meet regulatory requirements whilst retaining the aesthetic appeal of a building and ensuring appropriate security measures are considered. The key regulations that specifiers of automatic sliding doors need to be fully in compliance with are as follows:

Building Regulations of 2010

The 2010 Building Regulations detail the key considerations that specifiers of automatic doors must take into account. The regulations detail the requirements of access into buildings, including the use of powered entrance doors and glazing, all of which are key considerations.

BS EN 16005:2012

BS EN 16005:2012 is the code of practice for ensuring the safety of powered doors for pedestrian use. It is not a mandatory requirement. Should an action be brought as the result of an incident, the standard will certainly be referenced by investigators.

It is the specifier’s responsibility to ensure an installation conforms to the standard. This includes:

Full hazard analysis and risk assessment for the proposed installation, taking into account the type and volume of traffic.

The specifier should seek advice from automatic door specialists and other authorities when planning an installation.

Equality Act 2010

The Equality Act simplifies, streamlines and strengthens the law, giving individuals greater protection from unfair discrimination and makes it easier for employers and companies to understand their responsibilities. The Act replaces the Disability Discrimination Act but disability remains a key part of its composition.

The problem of balance

The challenge is to meet statutory requirements and maintain aesthetic appeal

In order to understand the capabilities of a bomb blast door it is necessary to first understand how a typical door works.

A typical sliding door assembly will be equipped with an infra-red unit to sense that a human is in close proximity and a motor to power the opening and closing of the door.

Typical sliding door assembly

The problem of keeping people safe during heightened levels of terrorism

Access lid

Motor

Sensor

Roller & Track

Door frame

Glazing

Floor guide

Finished floor level

Door frame

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The door hangs from a track and holds the vertical plane by a floor guide mounted at finished floor level. The door itself is made of aluminium frame and standard laminated glass comprising two annealed glazing sheets with 0.4mm thick poly vinyl butyrate (PVB) interlayer.

In order to resist attack, enhancements to standard automatic sliding door systems are required. The diagram below illustrates the header detail of a standard automatic sliding door in profile. The standard extrusion is heavier at the point of load, and standard header fixing bolts are M8.

The second image illustrates an enhanced security automatic sliding door. Header fixing bolts have been upgraded to M12 and the extrusion wall thicknesses enhanced throughout for added strength. A hardened blast shock anti-jump runner system has been added within the head and at the base of the door to avoid any horizontal movement (shown in red). This restricts the door from fully ‘jumping’ track when experiencing the high forces involved in an explosive event.

The final image shows the bomb blast automatic sliding door. Header fixing bolts have been upgraded to M12 and fixing centres have been reduced to provide the most secure fixing. Additionally, a spring steel plate has been added above and a deformable plate has been added to absorb the initial blast and prevent projection of the door into an occupied area. Extrusion wall thicknesses have been increased throughout which adds strength to the supporting head track and door running system. The entire door is also fitted with an enhanced operating system to cope with the increased weight.

Enhanced and bomb blast protection

Enhanced protection for sliding doors

Standard Enhanced Bomb Blast

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It is not only the door system which requires enhanced functions in order to cope with a potential terrorist incident. Glazing must also be considered.

The first image shows the standard door frame and glazing. Here, the door frame extrusion wall is 2.5mm thick and the annealed glazing sheets are each 3mm thick, with a 4mm thick poly vinyl butyrate (PVB) interlayer, which provides strength and holds shattered glass in place following a shock or breakage.

The door frame overlaps the door glazing by 10mm. A packer is installed to prevent the aluminium frame and glass coming into contact and a cosmetic rubber gasket and locking bead are used to secure the glass in place.

The second image shows the enhanced door frame and glazing. The door frame extrusion is still 2.5mm thick but the glazing is annealed glass sheets that have been increased to 5mm thick with a 0.8mm PVB interlayer. This totals 10.8mm thickness. A packer is present, as before, but a structural sealant now bonds the glazing and beading to the door frame, and the frame extends 10mm over the

Glazing

glazing. Cosmetic silicon seal and rubber gaskets are once again used.

The final image shows the bomb blast door frame and glazing. The crucial difference here is that the door frame is built around the glass. Door frame extrusion thickness is 4mm throughout. Glazing to each door leaf has a total thickness of 15mm. This is made up of three 4mm thick annealed glass sheets and two 1.5 mm thick PVB interlayers.

In addition, there is a special structural bonding of glass to the door frame. This has a manufacturing time of ten minutes but requires 21 days curing for full adhesion. Once again a packer locates the glass in the frame, this frame overlaps the glazing by 35mm. A cosmetic silicone seal is used to hold the glass in place. These changes add vital strength, whilst maintaining the flexibility and ductility of the door framing components.

A system of structural bonding adds vital strength to glazing

Standard Enhanced Bomb Blast

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Finally, the threshold, which plays a key role in bomb blast protection, must be strengthened. The first image shows standard door type with a standard roller floor guide. The floor guide is fixed by M6 expanding bolts (dependant on floor type) with a length of 60mm.

The second image shows the enhanced door. An upstand is added to ensure the door is retained within the door frame after an attack. The door upstand is 45mm high and 4mm thick, 316 grade stainless steel. The floor guide is fixed by expanding bolts (dependant on floor type) with a length of 100mm.

The final image shows the bomb blast door. A 60mm tall upstand with a 150mm overlap of door leaf and reinforced floor guide is used. Again, this is 316 grade stainless steel. These upstands are fixed to the structural steel with M12 studs.

Threshold

The differences: Threshold details in profile

Standard Enhanced Bomb Blast

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The three different types of doorset require specific overlap dimensions. The standard doorset has no upstand and requires only a 45mm overlap of the structure when the doors are fully closed.

The enhanced door set has an upstand of 100mm width, which requires a 45mm overlap with the structure.

The bomb blast doorset has a 140mm wide upstand, and requires a 150mm structural overlap.

Building fabric overlap

The Differences: Building fabric overlap (in plan)

45

45

100

150

140

Standard Enhanced Bomb Blast

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Designing the building structure as part of the solution

It is important that specifiers recommend doors for high risk facilities which correspond with quality standards. In the UK, the key standard is ISO EXV 45 with the US equivalent being the General Services Administration (GSA).

Testing

UK Terminology US GSA terminology(performance level)

Protection level Hazard level Description of window/glazing response

Break Safe 1 Safe None Glazing does not break. No visible damage to glazing or frame.

2 Very High None Glazing cracks but is retained by the frame. Dusting of very small fragments near sill or on floor acceptable.

3a High Very Low Glazing cracks. Fragments enter space and land on floor no further than 3.3ft from the window/door.

Low Hazard 3b High Low Glazing cracks. Fragments enter space and land on floor no further than 10ft from the window/door.

4 Medium Medium Glazing cracks. Fragments enter space and land on floor and impact a vertical witness panel at a distance of no more than 10ft from the window at a height no greater than 2ft above the floor.

High Hazard 5 Low High Glazing cracks. Fragments enter space and land on floor and impact a vertical witness panel at a distance of no more than 10ft from the window at a height greater than 2ft above the floor.

Testing replicates a 100kg TNT explosion at 45m and 25m distance

Two individual tests are conducted. In one test a doorset is subjected to the force of 100kg of TNT equivalent, exploding at a distance of 45m. A second doorset is then subjected to the force of 100kg of TNT equivalent, exploding at a distance of 25m. The doorset’s ability to withstand the blast is then graded using the criteria set out in the chart below:

Doorset after test 1Capturing the explosion during test 1

Standard doorsets are available in many configurations. However, security enhanced and bomb blast certified doorsets are limited to single and double sliding doorsets, surface fitted, with or without side panels. The side panels must be manufactured to the same glass and frame specifications and be secured to the building fabric with comparable fixings. There are three key issues that must be taken into account when ordering bomb blast doors.

Specification considerations

What should you consider when specifying bomb blast doors?

Lead times

The standard lead time for automatic doors is 4 - 6 weeks. However, enhanced security and bomb blast doors required an additional 21 days for the structural sealant to cure. This can result in a lead time of 6 - 8 weeks.

Installation

Floor guides and upstands require substantial fixings into the floor. In the case of bomb blast doors, structural steels are required which must be specified by a structural engineer.

Maximum door leaf dimensions

Bomb blast consultants advise that the maximum size of a bomb blast or security enhanced door is 2400mm x 1475mm (3.6m2)

The height-to-width aspect ratio for each leaf must not exceed 2.5:1

Configuration Standard Enhanced Bomb Blast

Folding 3 7 7

Telescopic 3 7 7

Revolving 3 7 7

Balanced 3 7 7

Single sliding with (or without) side panel 3 3 3

Bi parting sliding with (or without) side panel 3 3 3

The problem

Security formed a major part of the brief for Terminal 5 due to increased terrorism threat levels, particularly following the attempted car bombing at Glasgow Airport in June 2007. As a result of this incident, the Government’s ongoing threat assessment level for UK airports was reclassified as ‘Severe’, meaning an attack is highly likely. The challenge with Terminal 5 was to strike a balance between easy public access and the high levels of security required.

Case study - Heathrow Terminal 5

The challenge to combine accessibility with bomb blast protection

The solution

It was essential that the Terminal would be as accessible as possible to facilitate movement for the tens of millions of passengers using it every year, whilst providing necessary protection against terrorist attack. As a result, Ingersoll Rand was chosen to supply a number of products to offer added security and protection.

Dor-O-Matic bomb rated automatic doors were specified and installed on all main entrances throughout the Terminal building. Specifically designed for high risk areas such as government offices, transport hubs, public buildings, military establishments, financial institutions and other potential targets, the Dor-O-Matic bomb rated doors are a perfect solution for projects requiring a blast resistant, secure bi-parting automatic door system.

Designed and manufactured to be similar in appearance and with the same access performance of the standard automatic door range, the bomb rated doors are also able to withstand the blast overpressures associated with a vehicle bomb and provide protection from high velocity shards of glass being projected into an occupied area. The doors are capable of withstanding the effect of 100kg TNT explosions at both 45m and 25m. The testing was carried out in accordance with the US General Services Administration, International Standards Organisation (ISO) and Bomb Blast Standards. Blast gauges were used to measure the blast pressure and the blast loading for each test. As a result, the range meets or exceeds GSA (C) and ISO EXV 45 and ISO EXV 25 standards.

In addition to bomb blast doors, Ingersoll Rand’s Martin Roberts fire and acoustic performance doorsets and

stainless steel mesh gates were installed in customer interface areas, toilet blocks, stairwells and the multi-storey car parks. Steel doorsets are ideal for transportation sector due to the demanding criteria set by high volumes of traffic and likely abuse.

Key to the use of Ingersoll Rand’s steel doors was the combination of strength, durability and aesthetics to provide innovative high performance door products for the applications. Factory prepared to facilitate accurate and time-saving installation on site the doorsets are supplied complete with hardware sets and give the specifier maximum choice.

This large specification pulled together the complementary products which Ingersoll Rand has on offer to meet the diverse and different requirements of such a complex scheme.

Whilst Ingersoll Rand Security Technologies has taken every care to ensure the accuracy of information, data or advice contained in this literature, no liability in respect of such information or advice, whether given negligently or not, can be accepted by the company. Ingersoll Rand retains the right to amend the technical specification of any range of equipment shown without prior notice.

Ingersoll Rand Security Technologies is a leading global provider of products and services that make environments safe, secure and productive. The sector’s market-leading products include electronic and biometric access control systems; time & attendance and personnel scheduling systems; mechanical locks and portable security; door controls, exit devices and architectural hardware; performance steel doorsets and automated openings; and other technologies and services for global security markets.

Ingersoll Rand Security Technologies

© 2013 Ingersoll Rand Company Limited

Bescot Crescent Walsall West Midlands WS1 4DL

Tel. 01922 707400 Customer Care Centre Tel. 08706 012012 Customer Care Centre Fax. 0800 834103

Email info@ingersollrand.co.uk Web ingersollrand.co.uk

References

• Ingersoll Rand dedicated website - www.security.ingersollrand.com/bombblast

• ASIAD – Aviation Security In Airport Development - www.airport-world.com/item/723-asset-protection

• CPNI – Centre for the Protection of National Infrastructuret - www.cpni.gov.uk

• Contest – Government counter-terrorism strategy - www.gov.uk/government/policies/protecting-the-uk-

against-terrorism

• Home Office - Safer Places - www.gov.uk/government/publications/safer-places-the-planning-system-

and-crime-prevention

• NaCTSO – National Counter Terrorism Security - www.nactso.gov.uk

• TRANSEC – Transport Security Directorate in the Department for Transport - www.gov.uk/government/

policies/managing-the-risk-to-transport-networks-from-terrorism-and-other-crimes

• Crowded Places : The Planning System and Counter Terrorism - www.gov.uk/government/publications/

protecting-crowded-places

• London First - www.londonfirst.co.uk

• ADSA - Automatic Door Suppliers Association - www.adsa.co.uk

(Crown Copyright is acknowledged)