The Railway Children by E. Nesbit is a novel about three children whose father 'goes away' and have to move to the country with their mother and the various scrapes they get into and out of, most of which have to do with the railway.

The cover I used was just plucked off https://www.booktrust.org.uk/book/t/t.... The edition I read was downloaded off of Project Gutenberg which had its initial upload in 1999, but the original book was first published in 1906.