Airport Design and the Role of Glazing Systems
Worldwide, Kenya has been much in the news recently, and not for the right reasons. The Westgate shopping mall massacre in which at least 67 people died is a shocking reminder that any building where large numbers of people gather can be a terrorist target.
That threat is most real at airports, which can have a pivotal role in regional or national economies and, for the terrorists, significant news value. Airports have therefore seen the greatest investment in security and building research, although the recent Westgate attack is a reminder that the threat is much wider. Nor is the threat confined to larger hub airports. The 2007 attack at Glasgow airport underlines how terrorism can be national or local, meticulously planned for maximum effect, or simply opportunistic.
But it would be simplistic to consider airport security purely in terms of terrorist threat. In August last year, Kenya was again in the world’s media spotlight following a major fire at Nairobi’s Jomo Kenyatta airport, the busiest in East Africa, and of major economic importance for the country – both for inward tourism and exports, mainly cut flowers.
The catastrophic fire, most probably started by faulty wiring, demonstrates how a major infrastructure asset can quickly become a national liability. The airport, built in an age before modern fire regulations and protective systems, was extensively damaged – the blaze gutted the arrivals terminal – closing off a vital transport gateway. However, perhaps remarkably, there were no casualties.
The Nairobi fire is a stark reminder of the importance of identifying every conceivable threat, that strategies to deal with them are robustly examined, and emergency procedures routinely tested – which was not the case in Nairobi with its aged infrastructure, inadequate emergency equipment and poor response planning. However, Boston airport last year had to apologise for holding an emergency training exercise on 9/11. A week later there was a fuel pump fire at the airport.
Countering these threats starts with a comprehensive assessment of the likely (or unlikely) risks the airport might face in terms of an accidental or deliberate interruption to its operations. Modern building safety is largely determined by taking a multi-disciplinary approach to assessing these hazards – from power failure to cyber-attack, from civil disorder to fire and explosive detonation.
Assessment involves reviewing the architectural design of the all airport infrastructure, establishing fire safety objectives, identifying fire hazards and examining all possible emergency situations. In an airport, with its unique security profile, that includes creating specific evacuation zones to prevent occupants passing from landside to airside, or vice versa, without necessarily evacuating the entire terminal.
In that respect, airports are much like shopping centres: a large outer structure, into which are dropped functional areas – everything from airport and airline administration to security and baggage handling, and onto retail and food and beverage outlets. Visit any modern airport and parallels with shopping centres are plain.
Airports can be filled with people of different nationalities, with young families, and of varying age and mobility. Many will also have large amounts of luggage so, in the event of an emergency – particularly at peak periods – evacuation times may be greater than predicted, and, and evacuation routes and exists must be designed to cope.
Like shopping centres, airports can be filled with people of different nationalities, with young families, and of varying age and mobility. However, making evacuation models harder to predict, many of those occupants will also have large amounts of luggage. In the event of an emergency – particularly at peak periods – evacuation times may be greater than predicted, and, and evacuation routes and exists must be designed to cope.
For an airport, other factors might have to be considered – from the kinds of threat specific to that country or region, to the airlines that make use of the facility. For example, a 1985 bomb explosion at Tokyo’s Narita airport killed two baggage handlers. The bomb had been destined for an Air India flight and had exploded prematurely. Less than an hour later another Air India flight exploded in mid-air off the west coast of Ireland killing all 329 people on board.
There are a number of assessment methodologies to understand the potential threats, identify the assets to be protected, and how best to mitigate against those risks. That assessment then guides the design team in determining acceptable risks and the cost-effectiveness of the measures proposed, both airside and landside.
That was brought home in the UK when Irish terrorists fired mortar bombs onto the runway at London Heathrow in 1994. They failed to detonate but underlined how airport security is an issue that has to be considered outside, not just inside, the airport’s perimeter.
The same tactic was used four years later in 1998 when left-wing terrorists fired projectiles into a cargo area of Tokyo Narita airport, injuring an airport worker. The attack came at a time of heightened security, with athletes and officials gathering for the Nagano Winter Olympics. The airport also saw a firebomb attack on its control tower two months before its official opening in 1978.
Another attack from outside the perimeter took place in 2012 on Bacha Khan International Airport in Peshawar, Pakistan, causing multiple fatalities. The Taliban attackers first detonated a car bomb against the perimeter before mounting their main assault using rocket launchers, suicide vests and small arms.
That, in essence, is the airport designer’s conundrum: how to build a facility able to safely handle large numbers of people, while making their experience as hassle-free as possible. Official guidance now covers all of an airport’s critical functions, from security checks on passengers to aircraft hold baggage, from the location of car parks to the glazed elements in the building’s design. The guidance also includes the design of areas immediately outside terminal buildings to create an exclusion zone for unauthorized vehicles.
Stand-off distance is an important consideration. A bomb detonating at seven metres from the terminal façade will, depending on the size of the bomb and type of explosive, generate blast pressure of up to one ton per square foot. At 30 metres, blast pressure falls to one-tenth of a ton per square foot – within building regulation parameters on structural integrity.
Modern building design, in airports as elsewhere, now makes extensive use of glass. It brings in ambient light and creates a more pleasant interior environment. Interestingly, a survey last year found that London Luton airport has the lowest passenger satisfaction of any UK airport – a facility that many considered gloomy, and which is one of the oldest terminals in the UK.
The extensive use of glass has come about as a result of investment in innovation, both to develop new laminated glass types and framing systems able to withstand blast pressure, as well as to accurately evaluate those systems using a variety of assessment and computational tools.
Wrightstyle has gone beyond computational assessment to also conduct live bomb testing. One test involved a simulated lorry bomb attack (500 kg of TNT-equivalent explosive) detonated 75 metres from the test rig, followed by a simulated car bomb attack on the same glazing system (100 kg of explosive), detonated at a distance of 20 metres. Both tests were equally successful.
As recent events in Kenya have shown, both fire and terrorist attack are potent threats to be assessed, comprehensively guarded against, and with regular rehearsals to ensure that response teams can deal adequately with any emergency.
That multi-dimensional approach also extends across the built environment, developing next-generation products and systems to ensure new levels of fire and terrorist protection. The specialist glass and glazing industry remains at the forefront of that innovative research process.
For further information, go to www.wrightstyle.co.uk