Several eye-catching hi-tech measures have been announced by the government to boost security and fight terrorism on public transport.
By Jenny Matthews
But it seems we should not get too excited just yet about undergoing body scanning, facial recognition checks and the like whenever we get on a bus or train.
A conference held by the International Association of Public Transport in London this week has started comparing ways public transport bosses can combat terrorism.
At the conference, UK Transport Secretary Alistair Darling talked about exciting new technologies such as a "millimetre wave scanner" - being trialled on the Heathrow Express next year.
"Intelligence vision" CCTV was trialled in London - without much success
He also pointed to trials of "intelligence vision systems" - enhanced CCTV which can automatically spot suspicious behaviour such as someone leaving a package.
But most experts at the conference felt that wide use of such technology on the transport system was extremely unlikely in the foreseeable future.
In trials of the enhanced CCTV system, for example, London Tube staff could identify abnormal behaviour more quickly than the software. The kit also had a tendency to raise false alarms.
Alain Caire, director of security at RATP (the Paris region transport authority), also cited problems with facial recognition technology, which compares people's faces with, for instance, those of suspects wanted by police.
"A few years ago, it took 10 or 15 seconds to compare a face. Now it takes three," he said. "But if you are comparing that face with, say, 20 terrorists' faces, that's 100 seconds, so it becomes impossible."
European Commission security expert Marjeta Jager said aviation-style security was not viable on public transport systems, given that they had to be "open, economic and accessible".
Even Mr Darling said there was no way a sealed, airport-style system could be created on public transport, because of the sheer volume of people using transport networks (3m journeys a day are made on the Tube in London, for example).
In fact, it seems the key to safety could lie in what
Mr Darling referred to as a "layered approach" - some technology, but also comparatively unexciting things such as making sure breathing apparatus is updated, keeping CCTV working, training staff and testing equipment.
Certainly it is in these areas that London Underground is focusing most of its efforts.
Already one of the world's biggest users of CCTV, it is planning to double its 6,000 cameras to 12,000 in the next five years.
London Underground is also focusing on "high-visibility staffing and policing", to at once reassure passengers, and deter terrorists.
Changes to the Tube rota are being made to remove staff from ticket offices and have them working on the platform and in ticket halls.
And police numbers have also been boosted - in 2003 there were 450 British Transport Police officers on the network; now there are 650 and London Underground is calling for 100 or so more.
High visibility policing and staffing is seen as reassuring, and a deterrent
Many of the experts also said one of the most important lessons which had been thrown up by terror attacks in Madrid, London, Moscow and the like was the importance of planning - of holding drills, drawing up procedures, and keeping these under constant review.
Tim O'Toole, managing director of London Underground, said planning exercises held in the UK before 7 July had proved very worthwhile.
They "created a shared knowledge as to who would do what," which meant the transport network was back up and running relatively quickly afterwards, he said.
However, he admitted the planning had anticipated a single incident rather than multiple attacks.
Planning in future would have to be "far more ambitious", he said.
Meanwhile, says Mike Brown, "one of the best technologies we have available to us is the eyes and ears of our staff".
And of course, passengers have their own part to play in keeping transport safe.
"They must be prepared to report anything suspicious, however trivial," said Mr Darling.
They are also urged to do their bit by not leaving laptops, briefcases and bags behind - which people still seem to be doing in their dozens.
"We had a huge number of alerts immediately after 7 July, and there's still a bit of that. We get a handful a week of incidents where baggage has been left," said Mr Brown.
Normal CCTV is being boosted on the London Underground
But all this is not to say the experts believe more hi-tech security checks will never be used more widely on public transport in the UK.
Marjeta Jager said some baggage checks and screening "could be worthwhile", even if they are not systematic.
It could be possible to introduce higher standards of security on long-distance train and bus services, she said - the public may be more prepared to tolerate the extra time required for such checks, and there are fewer people to deal with.