THE ATTACKS on the Madrid railway system again exposed the vulnerability of modern cities to terrorism.
In the two and a half years since 11 September, security has been stepped up across all aspects of society. But how effectively and at what cost?
Britain's network of 11,000 miles of track and 2,500 stations used by five million people a day is vulnerable. But airport-style security checks on the rail and underground networks have been ruled impractical and prohibitively expensive. The Eurostar service from Waterloo is the only one with metal detectors and baggage scanners.
Verdict: A secure and open rail system is vital to the economy. While there have been no attacks since 11 September, fear has grown among rail travellers.
Security was tightened after 11 September. All bags are now screened for traces of explosives and radiation detectors were installed.
Fighter jets are on permanent stand-by at RAF bases in Norfolk, Cornwall, and Somerset in case of hijackings. The pilots have psychological training for the prospect of shooting down a passenger jet.
Verdict: Confidence has been restored but air marshals have proved controversial with pilots while passengers have been forced to contend with longer check-in procedures. Another hijacking could have dire economic consequences.
The government issued ports and ferry operators with new security advice in light of continental warnings of a possible terrorist attack against ferries in November 2002.
The Royal Navy is to get powers to board ships suspected of carrying components to make weapons of mass destruction. Screening for radioactive materials has begun for all traffic coming into Britain.
Verdict: Remains one of the great areas of vulnerability to the global economy. The high seas have proved notoriously difficult to police.
Concrete barriers were placed in front of Parliament in May 2003 and the US embassy in London is ringed with concrete barriers and metal fencing. However, David Blunkett has rejected calls for more physical barriers, saying it is good intelligence rather than "concrete blocks" that prevents terrorist attacks.
Verdict: Bombing of the British embassy in Istanbul proved that buildings remain vulnerable. Not all sites can be guarded and doing so ties up manpower that may be more effective elsewhere.
Security was tightened at last year's Wimbledon, with the staff vetted by the Home Office, metal detectors introduced and spectators body searched.
Verdict: A terrorist attack on a packed stadium remains a nightmare scenario for strategic planners. The forthcoming Olympic Games in Athens pose a massive security headache. …