While efforts put in place to secure air travel have led to recent failed terrorist attacks on both airlines and airports, they may cause terrorist organizations to shift their focus to other “worthy” types of transportation. The most vulnerable of these are commuter rail and cargo trains whose security measures have fallen behind the rapid advances made in aviation – a fact which makes them a perfect target of terrorist groups in the future.

The threat to rail is nothing new. The July 2006 serial bombings on Mumbai’s suburban trains that left over 170 passengers dead and hundreds more wounded, demonstrated the vulnerability of passenger rail systems to terrorism. These deadly bombings marked the third year in a row in which commuter trains were targeted by Jihadi terrorist cells around the globe. The previous attacks, of course, include the July 2005 London tube (and bus) bombings that left 52 people dead and the March 2004 Madrid train bombings that caused the death of 192 passengers and wounded over 1700 others.

According to a 2006 Congressional Research Service (CRS) report prepared for the US Congress (citing the Rand corporation database), an estimated average of 30 annual attacks on rail transportation interests took place between 1998 and 2003. However, the attacks mentioned above have been among the deadliest.

Attacks on trains and stations have devastating effects not only in terms of casualty numbers but also financially. On top of the initial material damage, there is often an immediate economic impact due to the vital role public transport plays in many financial centers as well as a more lasting impact caused by the avoidance of public transportation by the populace for fear of further attacks. In other cases, preventive measures by authorities have shut down transportation nodes causing major disruptions and cancellations of scheduled trains.

For example, following the suicide bomber attacks on July 7, 2005, central London's public transportation came to a standstill for most of the day because of the complete closure of the underground system. While most of the underground transport (except at the affected stations) restarted the next morning, many commuters chose to stay home. In Israel, it took years and the creation of special armed guard units traveling on board buses and trains to restore the public’s confidence after a wave of suicide bombers targeted public transportation, including buses and train stations, during the second intifada.

The main source of rail transport’s vulnerability lies in its exposure; as trains make the entire length of their trip on the ground, passengers or cargo on board are exposed to attack throughout the route. Because of this increased weakness, attacks may range from conventional bombings, missile attacks, car derailments (using an assortment of barriers), chemical attacks and cyber-attacks, which in the best case scenario will halt train movements and in the worst will cause deliberate collisions.

Cargo trains, especially those carrying large quantities of fuel, volatile/toxic chemicals or other hazardous materials that could be used as Weapons of Mass Effect (WME) are also targets. Many of these materials are transported in large quantities by trucks or rail, presenting a very real possibility that these shipments may be targeted by terrorists taking advantage of the fact that transportation routes and railways cannot be hermetically sealed. Such attacks are likely to take place on routes and railways passing through or in close proximity to urban centers as they aim to cause severe and lasting damage through chemical contamination. Like all major attacks and accidents, the material damage and fallout are often accompanied by severe business interruptions and resident evacuations.

In August 2000, for example, at least 17 people were killed and many others injured when a train carrying Liquefied natural gas (LNG) from Mombasa to the capital, Nairobi, exploded and caught fire near Athi River Town, some 25km/15.5 miles east of Nairobi. The intense fire spread to houses along the tracks causing casualties and material damage. While not a terrorist act, this incident portrays the damage such an attack can cause.

While security measures are often focused on preventing terrorist attacks, anarchist and other politically-based radical groups also pose a threat and have targeted trains in the past. While these groups’ acts of sabotage usually tend not to cause fatalities, they do cause material damage and levy financial burdens. On November 11, 2008, for example, French authorities detained at least ten suspects in connection with a series of acts of sabotage targeting the national rail network. In one incident, the alleged far-left group members laid concrete slabs on GTV high speed rail lines connecting Belgium and France near Perpignan. The train suffered damage but luckily none of the passengers was injured. The same group is suspected in causing an outage that caused disruptions to approximately 160 trains, including Eurostar service to London and Brussels, leaving thousands of passengers stranded. A more recent example would be the March 3, 2009 anarchist arson attack on the commuter train in the high-end Athens suburb of Kifisia in which eight of the Athens-Piraeus Electric Railways Company (ISAP) train's carriages were destroyed, and the station sustained damage. The assailants warned passengers to exit the train before pouring gasoline on the train and throwing Molotov cocktails at it. While no one was injured, the damage was estimated at more than 13 million euro. Though at least one security guard is stationed at each ISAP station and cameras are installed in all stations the unidentified gang managed to flee.

While the incidents mentioned above demonstrate the increasing threat to and vulnerability of the rail system, it seems that little has been done to increase safety and security. In many locations around the world, security in this industry depends largely on CCTV, which, while useful, has often proved to be less than ideal as a preventative especially compared to increased training and personnel. For example, the New York Metropolitan Transportation Authority (MTA) – which operates the largest and most diverse transportation system in the U.S. – spent US$450 million between 2002 and 2008 on its electronic security program while only spending US$25 million for security training during the same period. A January 2008 report by the New York State Comptroller’s office later revealed that some of the technology wasn’t working as designed.

Though CCTV has gone through tremendous changes in recent years, including the development of sophisticated "intelligent software" able to detect suspicious people or abandoned items, the recent suicide attacks on the tube system in the U.K. have proven that CCTV is useful in the prevention of criminal activity and in follow-up investigations, but has no deterrent impact on terrorists.

A further problem is presented by the integral role rail transport plays in certain cities and the weaknesses presented by the need for easy access by the populace– with multiple entry and exit points at stations and the need to maintain schedules, security at the level seen in aviation has proven not only difficult but nearly impossible to attain. There is a pressing need for more luggage and carry-on bag checks (not only during high alerts), more security personnel constantly checking for unattended items and baggage, and police officers trained in behavioral screening and familiar with suicide bomber indicators – all of which are all likely to deter terrorists. Additionally, intelligence sharing and passenger manifests on international routes should be conducted.

As terrorists are getting more sophisticated, more drastic measures, including the development of customized industry security equipment, is needed. In the future, corridors or entranceways could be turned into sniffer tunnels, able to detect explosives residues on a group of passengers. Once an alert is made, the specific passenger group, which passed together at the “tunnel”, would then go for an individual security screening.