Greece train crash: The scene is 'horrendously bizarre', but questions now turn to how the tragedy happened

The police wave us through. We are allowed to drive off the motorway, down a rutted track and into a field, and there, in front of us, is a sight at once extraordinary and terrible.

A railway carriage, slumped on its side, its windows broken. The graffiti is still all over the paintwork, like a touchstone to normal life, but there are people with flashlights crawling underneath, looking for any signs of bodies.

There's nothing normal about this at all. Nor of the freight containers that stand behind, remnants of the freight train that was hurtling along this track on Tuesday night.

Such a mundane, everyday thing - freight being moved; students coming back from holiday. And yet now charged with such sadness.

Dozens of people died here, in this field, when the two trains crashed into each other. From where we stand, it's easy to see that the passenger train would have been emerging from a tunnel when this accident happened.

One wonders if the driver would have had any time to react. Like so many thoughts about this accident, it's a bleak one.

The rain begins to fall. The search continues, with huge lights illuminating the wreckage and cranes looming over the scene.

It is quiet, and there is a sense of resolve, but there's also a feeling of resignation. Something terrible happened here, and time can't be reversed.

It feels so horrendously bizarre, so lit up against the night sky, that it could even be a film set. But, of course, it's actually something desperate and ghastly. The evidence of a crash that should never have happened.

Because amid the despair there is also recrimination and a simmering desire for a reckoning. This was not a disaster that came as an absolute surprise to some in Greece, for the shoddy state of the nation's small railway network has long been a source of contention.

Just a month ago, one of the rail unions warned that underinvestment had raised the spectre of a serious crash. The president of the rail regulator said signalling systems were still reliant on being operated manually, leaving them open to "human error".

And so it was, here in northern Greece, that a passenger train emerged from a tunnel to smash head-first into a freight train coming in the opposite direction, along the same line.

Does the blame lay with one person, or is it the result of underinvestment?

If you run a railway, there cannot be a more fundamental failing than this. Just a matter of hours after the crash, the police arrested the station master from Larissa train station, charging him with a range of crimes, including multiple counts of manslaughter.

But already, across Greece, a debate has begun as to whether this is truly the responsibility of a single person, or simply the inevitable result of a failing network that is, by comparison with other European railway networks, outdated and open to human error.

Outside Larissa station, some hours after the station master is arrested, there is a vigil organised by students. Candles are lit and prayers are muttered. "I feel sad, and angry, about what has happened," one of the students tells me, adding: "But I also know that I am lucky. I use that train. It could have been me on there."

Another tells me there needs to be a full investigation, and that he feels a sense of disbelief. He doesn't know when he will want to use the train service again.

This is a nation that has entered a period of national mourning. Train workers will stop work to register both respect towards the dead, and anger at what they see as a lack of investment. And the prosecutor will soon start to question the station master accused of causing all this death.

Disasters - especially avoidable disasters, and particularly train crashes - are followed by periods of introspection and doubt. But in this case, there is no question it is needed.

There is no excuse for what happened here, no excuse for the devastation that litters this field, for the dead, the dying and the injured.

It shouldn't have happened. The challenge for Greece is how to ensure that it never happens again.