Seven people have died after a high-speed train hit a car on an unmanned level crossing in Ufton Nervet, near Reading. Rail expert Christian Wolmar gives his assessment.
Q: What are your impressions about what went wrong?
What is awful about this is the similarity with the crash that killed 10 people at Selby three years ago where again it was a car that got onto the track that then derailed the train.
This is quite a rare event because most of the time when cars get on tracks, they are knocked away by the train.
But in this instance clearly the car got knocked underneath the train and derailed it. The important thing to emphasise is that this is a road crash that has effectively caused a rail disaster.
Q: What will investigators be looking for?
They will be looking at the car, they will be checking that the barriers were working properly, which is highly likely - these things are failsafe.
They will be concentrating on looking at where the car was when it was first struck.
My sources tell me the investigation is centring on suicide but that is not proven. If that is true, it makes it almost impossible to prevent.
Q: This will raise concern that there is always going to be risk where cars have to cross rail tracks where trains are travelling at more than 100mph.
The unions are saying 'Oh, we should have underpasses everywhere'. The cost of that would be in the order of billions of pounds.
Level crossings have been taken out on main, very heavily used lines but you can't possibly have underpasses everywhere, I'm afraid.
In terms of risk assessment it is not worth doing.
The money would be better spent on kidney machines or the NHS or something.
These are generally little used roads. There are about 10 people killed a year on level crossings but in terms of international comparisons that is quite a low rate.
It is just like road accidents - they happen and sometimes there is not an enormous amount you can do about them.
Q: The rail unions point to the rail inspectorate, which says that level crossings pose significant threats to safety.
There is a problem obviously in that 10 people a year die but 3,500 people die on the roads every year.
It is very rare that the rail passengers get injured or killed in these sorts of incidents. Most of the time it's the motorists or people who basically made a mistake and got on the track at the wrong time.
You just cannot spend billions of pounds replacing level crossings. It's as if you tried to make every traffic light in town centres into an underpass or an overpass.
Q: Are there any obvious safety measures that could be put in place at little cost - CCTV perhaps, motion detectors to tell the signalmen if there's something across the line at the crossing.
The idea of sensors is probably not there yet in terms of technology.
There are some simple things. For example, when the barriers are down motorists tend to wiggle across them because they are half barriers.
If you made each of the bits of road leading up to the crossing into a kind of dual carriageway and put a fence down the middle of the road for seven or eight car lengths, it would stop motorists doing that.
You could do that kind of thing to prevent motorists being daft.