Due to a scheduling clash brought on by her undertaking a doctorate, the books overlapped and intruded on each other so that Hay ended up writing them almost simultaneously over five years - a creative collision that would derail most writers. No wonder she was too caught up to notice the connection. The fact that she also had a newborn baby might explain it: Hay was doing a fair amount of shunting herself.

The accident in her second novel was inspired by one close to home. ''My father's father died in a railway accident. I remember hearing that my grandmother was woken in the night to be told the news,'' she says. We are talking just metres from the train line where he worked in the Illawarra region. ''I was interested in the fact that work used to be dangerous, that there was risk involved in making a living. Fortunately, today, most of us are much more removed from danger.''

But in 1948, when the story takes place, it was present. ''I was interested in the idea of accidental death occurring just after the war. For a man who had escaped joining up by being in an essential industry to die would be twice as shocking.''

Like Anikka, the young widow of the novel's title, Hay's grandmother was offered a job at the Railway Institute library.

During Heritage Week a few years ago, Hay's father Les (to whom the book is dedicated) gave a talk in the very same building while passing trains rattled the windows. ''I just thought, 'Wow! Imagine working there, with the constant reminder of what had happened from that sound'.''

Writing at home in Brisbane, where floodwaters forced her to contemplate sudden evacuation, Hay conjured up the dramatic landscape of the south coast of NSW. The Railwayman's Wife is set in the small township of Thirroul where she grew up, acutely aware of its rugged beauty, of the drama of a thin strip of settled land wedged between the towering walls of the sandstone escarpment and the ocean. She knew, too, that this was a place with a literary heritage, claimed by D.H. Lawrence as the setting for his novel Kangaroo. No pressure then.

''I found his [Lawrence's] presence encouraging, it made me feel it was possible to be a writer,'' says Hay, who is 42 and made a career as a journalist and then as a writer of non-fiction with The Secret, a book on Lord Byron's wife, followed by Gum, a fascinating survey of eucalypts and their botanical and artistic champions. Collaborating with photographer Robyn Stacey, she provided the text for two books, Museum and Herbarium, mirroring their exquisitely displayed collections in her own neat, almost forensically concise prose.

She concedes that she has an obsessive nature, which made immersing herself in natural history collections a joy.

''I am fascinated by scientific analysis and observation and my father being an engineer, well, there's precision there. I combine that with a strong visual sense inherited from my mother, who is a painter, so I find it easy to describe what I see.''

As Hay says apologetically, ''Not a lot happens in my books''. But she makes up for it with a charged intensity. Like her first novel, The Railwayman's Wife has a very deliberate architecture: a structure of alternate chapters that shift between past and present, layering characters' memories.

''At first I was not sure I could write fiction so I decided to trick myself into it by writing a book [The Body in the Clouds] that required lots of research to ease me into it gently. Now I've realised that whenever I tackle fiction I have a need to fracture the narrative by moving backwards and forwards in time. My next book will be about a woman my age, living where I live in Brisbane, but moving between today and 1962.''

Hay's relationship with Thirroul remains strong - her parents still live in the area - and her book eclipses Lawrence's not very good novel, though she's much too modest to say so. She knows her limitations: when she decided she needed a poem as an element of the plot for the novel she took a pragmatic approach and sub-contracted the job, recognising that poetry was not one of her talents.

Her friend and fellow novelist Michelle de Kretser recommended she contact Stephen Edgar, who wrote a poem to Hay's brief without reading any part of her manuscript. It now sits perfectly in the novel and the plot turns gently on the identity of its author - a nice echo of the way it came into being.

''I knew early on that a poem would be the linchpin of the story,'' Hay says. ''We all want to believe that when a person we love dies we will get one more message from them, which is why it is so hard to erase that final phone message, for example. Funnily enough, I got Stephen's poem as a phone message while I was at the Byron Bay Writers' Festival and did not meet him until the launch of the book.'' Verse, outsourced and delivered digitally: it's a very 21st-century way of carrying out affairs.

Even in casual conversation there is a deliberate precision about Hay's speech, so it's no surprise that the Edgar commission delivered such a successful result. She chooses each word carefully, like a surgeon selecting the perfect instrument for the incision he is about to make.

She has made Anikka an unsentimental character, resilient and free of self-pity. ''I read a lot of journals of women who lost men in the war and saw how they coped and just got on with it. And sometimes the effect of shock is that the loss does not register and you do things as normal before it sinks in. Children also demand that you stay practical and cannot indulge your sorrow. I myself don't know about loss and got very superstitious while I was writing this book that I might bring on some calamity. I kept rushing to my husband when he came home from work [Nigel Beebe, a scientist specialising in mosquito-borne diseases] just to make sure he was OK. Killing off a perfectly good husband [Mac, the railwayman] when you have a perfectly good husband is difficult.''

Hay says she dislikes gushy books. ''Privacy is my default setting and perhaps, as an only child, I understand self-containment. So I gave that quality to Anikka.''

Others in the book suffer more visibly than Anikka. Among those to return to Thirroul from the war is Frank Draper, a troubled doctor who cannot come to terms with his failure to help starving survivors of concentration camps. ''When I was writing Gum I went to talk to Les Murray at Bunyah and he told me about a doctor who had seen 500 people die on the first day of freedom. No one could make sense of that. So yes, Frank is an early example of what we now call PTSD [post-traumatic stress disorder].''

She has given Edgar's poem to a character called Roy McKinnon, a poet also back from the war. He begins to find hope and the possibility for renewal through visiting Anikka in the library and through conversation with her bookish daughter Isabel, surely a character modelled on the young Hay.

''I tried writing siblings in early drafts of The Body in the Clouds,'' Hay says, ''but was told their relationships were unbelievable, so I think I am destined to write only children forever.'' While Hay's prose suggests a tidy mind, free of clutter, that does not mean it lacks emotion. One reviewer has even described the book as heart-crunching.

''A friend told me she thought it life-affirming until the final three chapters, then she said she hated it. But I can't do an ending tied up with a bow when writing about random accidents and postwar messiness. Life is not neat in its narrative.''

She pauses before adding, with a barely discernible tremor sneaking into her voice, ''I don't think I could read from that final section in public''.

The Railwayman's Wife is published by Allen and Unwin, $29.99. Ashley Hay will be a guest at the Sydney Writers' Festival, May 20-26 (swf.org.au).