The terrorist threat to critical infrastructure, especially transit systems, has increased with the rise of ISIS. But these targets have long been uppermost for attacks. Apart from aviation, trains and subways are attacked most often; from 1987 to 2003 there were 181 attacks with 467 casualties. In 2004 and 2005, Madrid and London respectively suffered the worst terrorist attacks to date in each country – which targeted both cities’ train and subway systems. Ten years earlier, the most devastating terrorist attack to date using CBRN involved five separate releases of sarin nerve agent on the Tokyo subway. If such a CW attack happened in London or New York, the transit service would be closed down for days, and if a radiological weapon were used, far longer.

Emergency services at Russell Square tube station after the multiple suicide bombings in London on July 7, 2005. Wikipedia

A triggered radiological or chemical disaster through a bomb, armed assault, cyber-attack or other form of infiltration into a facility or onto a transit system, would leave long-lasting effects on property and critical infrastructure. All CBRN attacks involve a degree of contamination, which even if minimal, require extensive and costly clean-up of premises – as seen following the polonium-210 poisoning of Alexander Litvinenko in London in late 2006, and after the anthrax mailing attacks in the US in October 2001. In each case high-profile buildings and locations were affected in major cities. There are legal and safety issues: both workers and visitors had to be reassured that buildings were safe to re-occupy.

For the E in CBRNE, attacks are too common to document in full. Massive explosions within a building or in the street, often from vehicle-borne IEDs, cause enormous damage not only to property but to rail and road transit systems and water and electricity supplies. The IRA bomb that blew up Bishopsgate in the City of London in April 1993 caused extensive damage to the water mains below the vast crater the bomb left. The damage costs exceeded £350 million; buildings up to 500 m away were damaged; 139,350 sq m of office space were affected, and over 500 tonnes of glass broken.

Protecting buildings

For CBRN protection, newbuild office and other vulnerable workplaces have to be designed with more than just protection against conventional IEDs. In the US, recommendations by the DHS National Infrastructure Advisory Council (NIAC) include timely, accurate information; advanced automated surveillance (including CCTV); detection devices for indoor and outdoor use; prioritisation of threats by installed systems (to avoid constant false alarms); communications interoperability; and – of growing importance – the capability of the organisation or facility for built-in resilience following an attack.

FILE - In this May 5, 1995 file photo, thousands of search and rescue crews attend a memorial service in front of the Alfred P. Murrah Federal Building in Oklahoma City.  More than 600 people were injured in the April 19, 1995 attack and 168 people were killed. Timothy McVeigh was executed in 2001 and Terry Nichols is serving multiple life sentences on federal and state convictions for their convictions in the bombing. (AP Photo/Bill Waugh, FIle)
The Alfred P. Murrah Building is shown from the air after the bombing and just shortly before demolition of the building on 23 May 1995. It took one massive ammonium nitrate bomb to cause this level of damage and to dozens of buildings in the vicinity. ©Social Security

An extensive system would include a chemical agent monitor that is not prone to false alarms. Particular attention would also be on mailrooms. The US has installed bio-detectors in many installations and locations, which act as biological ‘smoke alarms’ for near-real time detection. Radionuclide detection and identification systems can be deployed covertly in a high traffic area or portals as well as along parcel or freight conveyor systems, which should detect and identify both gamma and alpha-emitters. CBRN detection companies provide monitoring systems for underground facilities, including subway stations, government buildings, and nuclear power plants. Detect-to-warn systems in buildings and outdoor facilities are combined with video surveillance and air quality measurements.

Of prime importance is to mitigate an airborne agent through the control of the building’s ventilation system as this is a vulnerable aspect for spreading CBRN contamination. Active control of automated control systems would reduce the spread of the agent and limit exposure.

To plan measures for CBRNE protection, a full threat and vulnerability assessment (TAVA) would be performed on a building or location to provide the best and most cost-effective means. This would include threat modelling to create an integrated viable and workable design of the systems as well as training staff in how to run them.

Protection against explosive blast effects is incorporated into the design of new build premises in high-profile locations, while minimising disruption to the building’s efficiency. It will also factor in other aspects such as fire protection, staff and visitor accessibility and regular security procedures. It is more difficult, however, to put in ‘bolt-on’ measures to old or poorly designed buildings. But protecting the perimeter and parking areas of a building with reinforced bollards and designed street furniture, and replacing windows with reinforced glass, are feasible measures.

Focus on rail transit

Most CT experts say that screening passengers and baggage with detection systems would be impractical, prohibitively costly, and unpopular at train stations that handle thousands of passengers an hour.

The New York Metropolitan Transportation Authority (MTA) has deployed handheld explosive trace detection systems for random non-intrusive screening of passengers and their belongings. In New York’s Grand Central Station sensors are installed in metal boxes. Random inspections of luggage with swab wipe downs and scans are said to take 30 seconds. Armed Amtrak police and CT special agents with explosives-detecting K-9 units include undercover plain-clothes agents. The NYPD (New York Police Department) conducts random searches of the many thousands of bags carried by the seven-million-plus passengers travelling on the New York subway, into over 460 subway stations, and also on buses and suburban trains.

NYPD chem transit drill
An exercise was conducted by the NYPD on July 9, 2013 to test and study how chemical weapons could be dispersed through the air within the subway.

A CBRN exercise conducted by the NYPD in July 2013 tested how a chemical agent could be
dispersed through the air within the subway. A harmless odourless tracer of perfluorocarbons was released into the subway system for 30 minutes during the morning rush period. Air-sampling devices were placed on the street and within the system across the five boroughs. As the perfluorocarbons imitate characteristics of a chemical or biological release, results from the airflow study contributed towards learning how airborne toxins travel underground within the subway systems, and above ground near the entrances and exits.

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Andy Oppenheimer AIExpE MIABTI is Editor of CBNW (Chemical, Biological & Nuclear Warfare) journal and a consultant in CBRNE and counter-terrorism. He is author of IRA: The Bombs and the Bullets (Irish Academic Press, 2008) and of the CBRN and IEDs module courses for the St Andrews University Certificate in Terrorism Studies.