Rich is correct above, but with some variations and issues. In some browsers, after finding and choosing "Save as", you have 3 choices, and "Web Page Complete" seems to provide the best option. However, you are still only saving a true copy of a webpage to your hard drive. That means that anything on that page (photos, diagrams or web links) that works as a "link" will only be there as long as the linked material is still available. Remember the thread issues we've had before when various photo servers closed down?
We'll have to agree to disagree that Rich's method doesn't work. I saved the first page of the thread PASSENGER TRAINS - Let's See Them! using the Save As in Firefox. I selected Web Page Complete. I got the HTML file and the folder with all the support files, including graphics and even videos. The total was 361 files & folders for 188mb of files.