For example, Railways could be a relevant index entry. If possible, use capitals for the surname. Don't worry about trying to sort the index - that will all happen when it's added to the database. Ideally, you can send a file with a handful of entries to test it first. If you have already produced an index which could be added to our database and you are willing to provide the file or the index, please contact me .
Some people prefer to keep sorting their own index and accumulating the page numbers.
Other people prefer to just create a new line for every entry on every page. Either will be acceptable. If in doubt, have a look at a book with an index for ideas.