Next, a micro-second later, the confirmation of horror. A noisy rattling, like stone pebbles tapping underneath at the floor of the train. And above that, a sharp, piercing grinding, glass marbles ground underneath by great weights.

The train was braking sharply. Sitting across me, my girlfriend mirrored my own posture; hands clasped before mouth and nose below eyes reflecting the same knowledge, the same horror. It wasn't pebbles, marbles.

The sounds faded, the train halted in the dark night. Blissful silence. Definite silence.

The night and dark outside was welcome now. The mind flutters while the heart pounds. My first instinct was to seize my bag and pace further back, into another cabin. Walk into ignorance, into a cabin where I wouldn't know what was underneath me. Even touching the floor with my shoes revolted me.

Passengers around us began to complain about the idiocy of people throwing rocks at trains. S. read the bafflement on my face. ,,They don't understand,'' she apologized for them, standing up. ,,It's denial. The mind can't take it." But why could our minds?

Ahead, the driver had come out of its steering cabin. Head bent, he was leaning against the passenger doors of the train, rubbing his temples. S. was about to go to him, when the conductor passed, a woman in her early forties. Large, hasty steps, jaded look. She ignored the burble of questions raised at her; I pitied her immediately.

Every year more than 180 people in the Netherlands commit suicide by throwing themselves in front of a train. Death by train forms over ten percent of all registered suicides per annum.

Numbers differ per assessed organisation about the exact amount of suicides. Statistics Netherlands (CBS), the national register, reports different numbers than the inspecting agency of the responsible ministry (ILenT). The European Railway Agency (ERA) also uses these figures, likely provided by the ministerial agency.

I'm lost to explain why CBS counts suicides differently; their numbers of suicides by train are consistently lower.

CBS noted a total of 1500 suicides in 2003, of which 163 by train or metro. The ministerial inspection, the official body to register suicides by train in The Netherlands, noted 175 cases of suicide that same year.

While in the past 20 years there is little to no trend in the total number of suicides or in the number of train-suicides (from either dataset), data from the last available years (2010 and 2011) show the highest total number of suicides in 20 years. Subsequently, 2011 also was the year with the highest number of suicides by train in nearly 20 years.

Total suicides and suicides by train over the period 2003 - 2011. Source: Statistics Netherlands.

For train personnel, experiencing a suicide is a lottery. One driver never experienced one suicide during a career of forty years; another once had two in one week. It's always the eyes that haunt them, they say. People always look straight at you, the driver, when they jump.

There's a strict protocol when dealing with 'a collision with a person', as the euphemistic term puts it. On a passenger's train, it's the conductor who has a legal obligation to open the doors, climb outside, confirm the collision and walk back to search for the hit person, to establish if medical assistance needs to be offered or cover the remains before the clean-up team arrives. The driver, already exposed to psychological trauma, stays inside and warns the authorities.

Recently, a Dutch conductor raised a brief protest about this practice. He had experienced suicide by train 14 times now and was sitting at home, traumatised. In some instances of suicide, you can already know on forehand there can't be any help offered anymore, he argued.  The same news show also presented research numbers that more than a fifth of the personnel, having experienced a suicide, suffers psychological traumas.

One issue is that there are also people who jump in front of a train and survive, brutally inflicted and wounded. Whether they want it or not, they require medical assistance. From the over 6000 attempts to commit suicide since the 1980s, more than 500 survived.

The intercom crackled. We heard the conductor's voice, a bit too steadfast to be true, confirming the collision. Passengers voiced protests of disbelief and dismay. When the conductor reappeared, her face was taut. A young man, early twenties, began to fire urgent questions at her: he really needed to be in The Hague soon, when could they leave? S. intervened, brought the man to his seat, told him the reality that it could take hours. His mother was in hospital, he explained. He had had no idea.

Time passed. The rush from adrenalin wore thin, the heart slowly quieted. Faster than expected, the men in reflective clothing passed our windows outside the train; I could hear their footsteps. Big men, men with moustaches and loud voices, men with eyes that have seen too much.

On a track to the right of our train, another train had come to a stop. Passenger doors of both trains had opened, we were carried across from our train into the other, a big step across the night without touching the dark ground. Nearly two hours later we reached the empty platforms of The Hague. All the connecting trains had parted.

Per year, some four to five million Euros are lost because of train suicides in the Netherlands, the Dutch ministry has calculated. Apparently, they've only tallied the costs of the clean-up and the undertaker. Whether there also is a figure on the financial damage the train companies and network operator ProRail suffer remains unknown to me. Information on the psychological damage under their personnel seem to be kept guarded.

End last year, network operator ProRail, responsible for the Dutch train infrastructure, repeated its (annual) intentions to redesign accessibility of specific high risk locations which are infamous as a spot for jumping in front of trains. The operator fenced with a sum of three million Euros for redesigning accessibility the coming years. The infamous locations were kept secret.

I'd bet that one of these infamous locations is a local train station, halfway between Leiden and The Hague. It was the third suicide at that location in 2012.

The grinding noise had lodged inside my head, repeating over and over again; I would hear it for days on end.