I have to put my hands to my ears when I pass one of the sirens, wailing away into the fog from a post by the track side. More railmen scatter past me, shouting. The fire is at my back now, roaring into the cluttered girder space. In front, the smashed train lies on its side, crumpled and askew, thrown across the tracks like something dropped from above, like a dead snake, the frames of the broken cars its fractured ribs.

Beyond that another train, larger and with long, windowed carriages rather than low slab-sided freight cars. Men swarm over its torn surfaces where they merge with the long, still solid shape of a freight locomotive, its snout buried in one of the tall carriages. I see people being pulled from the wreckage. Stretchers lie by the track; more klaxons and horns sound nearby, obliterating the foghorns below. I am halted by the sheer manic energy of this desperate scene, watching the rescue operation. More people are brought, moaning and bloody, out of the passenger train. An explosion bursts from the wreckage behind me; men run towards this new scene of catastrophe. The wounded are being taken away on stretchers.

'You!' One of the men shouts at me; he is kneeling by a stretcher, holding a woman's bloody arm while another man ties a tourniquet higher up. 'Give us a hand; take one end of a stretcher, can't you?'

There are ten or twelve stretchers by the side of the tracks; men run up and ferry them away, but many people are left lying, waiting their turn. I step over the rail, from walkway to trackside, go over to the stretchers, and help a railman carry one. We take the first stretcher to the emergency train, where medical orderlies take it from us.

There is another explosion in the wrecked freight train. When we come back with the next casualty, the emergency train has been moved back up the track, away from the danger of explosions; we have to carry the stretcher with a moaning, bleeding man on it two hundred yards to the end of the freight train, where orderlies relieve us. We run back to the passenger train.

The next casualty may well be dead already; he pours blood as soon as we lift him. We are directed by a railway official, told to take him not to the emergency train but to another train further down the track, in the opposite direction.

It is an express, held up by the crash and taking some of the victims on board before ferrying them to the nearest hospital. We take the stretcher on board. In what looks like a soft-class dining-car, a doctor is going from victim to victim. We put our bloody charge down over a white tablecloth, splattering blood, as the doctor reaches us. He presses down on the man's neck, holding it; I had not even noticed that was where the blood was coming from. The doctor looks at me; a young man. He looks frightened.

'Hold this,' he tells me, and I have to put my hand to the man's neck while the doctor goes away for a while. My fellow stretcher-bearer runs off. I am left holding the faint pulse of the man on the dinner-table, his blood flowing over my hands when I relax or try to get a better purchase on the ragged patch of skin torn from his neck. I grip, I press, I do what I am told, and I look at the face of the man, pale with blood loss, unconscious but still suffering, free from whatever mask he ever chose to meet the world with, reduced to something pathetic and animal in his agony. 'OK, thanks.' The doctor comes back with a nurse; they have bandages, a drip, bottles and needles. They take over.

I walk away, through the whimpering wounded. I find myself in a passenger carriage, deserted and unlit. I feel faint and sit down for a moment, then when I get up can only stagger as far as the toilet at the end of the carriage. I sit down there, head pounding, lights in my eyes. I wash my hands while I wait for my heart to catch up with the demands my body is making on it. By the time I feel ready to stand again, the train is moving.

I go back to the dining-car as the train slows; nurses and auxiliaries from the hospital crowd in, taking the stretchers. I am told to get out of the way by three nurses and two auxiliaries clustering round a stretcher being taken towards the nearest door; an injured woman giving birth. I have to head back for the toilet.

And I sit there, thinking.

No one comes to disturb me. The whole train becomes very quiet. It shakes and jerks a couple of times, and I hear shouts outside the translucent window, but the interior is silent. I walk down to the dining-car; it is a different one, fresh and clean and smelling of polish. The lights go out. The white tables look ghostly in the light shed by the bridge outside, still wrapped in fog.

Should I get off now? The good doctor would want me to, Brooke would; so - I hope - would Abberlaine Arrol.

But for what? All I do is play games; games with the doctor, with Brooke, with the bridge, with Abberlaine. All very well, and with her quite sublime, save for that echoing horror ...

Do I go then? I could. Why not?

Here I am in a thing become place, the link become location, the means become end and route become destination ... and in this long, articulated symbol, phallic and poised between the limbs of our great iron icon. How tempting just to stay and so to go, to voyage out bravely leaving the woman at home. Place and thing and thing and place. Is it really so simple? Is a woman a place and a man just a thing?

Good heavens young-fellow-me-lad, of course not! Ho ho ho what a preposterous idea! It's all much more civilised than that ... Still, just because it seems so offensive to my taste, I suspect there might be something in it. So what do I represent then, sitting here, inside the train, within the symbol? Good question, I tell myself. Good question. Then the train moves again.

I sit at a table, watching the stream of carriages alongside; slowly we gain speed, leave the other train behind in its siding. We slow again, and I watch as we pass the place where the wreck took place. Jumbled freight cars litter the side of the track, twisted rails rear from the scored deck like so much bent wire, and smoking debris gutters in the drifting fog under bright arc lights. The emergency train lies a little way up the track, lights bright. The carriage shakes gently around me as the train gathers speed.

Lights flare through the fog; we flash through the main station of the section, past other trains, past local trams, through the lights of the streets and thoroughfares and their surrounding buildings. We are still gathering speed. Quickly the lights start to thin as we approach the section's far end. I watch the lights for a moment longer, then go to the end of the carriage, where the door is. I open the window and look out into the fog, tearing past the window with a roar itself patterned by the unseen structure of the bridge, echoing the train's headlong progress according to the density of girder work and added-on buildings around the track. The last few building lights fall astern; I work my hospital identity tag loose, pulling it slowly and painfully from my wrist, licking it when it sticks, finally hauling it off regardless, cutting myself.

Across the linking span. Still well within the range my identity bracelet allows me, of course. A little circlet of plastic with my name on it. My wrist feels odd without it, after all this time. Naked.

I throw it out of the window, into the fog; it is lost the instant it leaves my hand.

I close the window and go back to the carriage to rest, and see how far I'll get.