I opened the foroum page and i saw that there was an new anwser today on one of my posts.
http://www.trains.com/TRC/CS/forums/1128040/ShowPost.aspx
But to my surprize i realised that the last post was from June! And i think this is not the first time,i just did not give much attention, thought that it is my impression.But now i am sure.
Why is this happenig?
Somebody modified their reply.
Simply editing a response does not change the indicated date-time group for that response; it does change the date-time group on the index page.
I linked to the post and observed that there was a cluster of responses right after it was initiated back in May. Then someone picked up on the topic after a couple of weeks of inactivity and there was another cluster of responses at mid-June. I have observed this happening quite frequently. In fact, not too awfully long ago there was a post dating all the way back to 2001 and there had been a full five and a half year gap between the latest response and the previous one. I thought the topic horribly out of date but, nevertheless, someone had discovered it and decided it was worth a response. I never looked in to see if it had attracted any more interest and by this time it is probably buried back on page twenty or so!!!
Both yall are correct, however, what happens is when someone modifies their reply, it does change the forum’s “most recent post” that shows up on the forum index, whilst the post dates stay the same.
This is what I just saw happen with Railroad’s post.
I’ve see this happen from time to time. It comes in waves. Makes you scratch your head and wonder why - other than prehaps someone getting a little board with the current topics. Or maybe some just get a kick out of reaching back to resurrect a topic that has been in the grave for more than a year. [%-)]
Yep, a handful of posters think this is fun. It may actually be just one human and his “sock puppet” additional identities since they all seem to be active at once, but it’s apparently how he gets his jollies.
hides sock-puppet
What’s wrong with puppets? 
I liked the way the old forum software automatically added an “edited post” tag and time stamp. It was easy to tell when someone typed something to start trouble and then changed it and played innocent.
The advantage of quoting the origianl post.
Tom
There’s really nothing in the rules that prohibits bringing back old topics, nor do I mind so long as there is a point to it. I think it becomes annoying when someone abruptly posts a reply to a three year old topic as though it fell off of page one yesterday.
There was a member a couple of years back (can’t remember the name) who did this frequently. It was pretty bizarre. It wasn’t that the topics being brought back were controversial (as in attempting to re-ignite a flame war), but instead innocuous topics with harmless replies. It usually took a few posts before someone noticed that a couple of years had elapsed from one post to another. The reason for it all was hard to figure it out, because cries for attention usually follow a far less subtitle pattern. Maybe someone with a strange sense of humor?
Maybe somebody just was going thru older topics and saw one he wanted to reply to? I think I’ve done this. I’ve noticed it before too and if thers’s still a reason to reply then why not?
Very probably, a computer semi-literate who was checking out the (old format) forum “attention grabber” threads in year-old MR newsletters before deleting them (the letters, not the forums.) Then one day he noticed that the forum post dates were ancient and that there was a way to get to the up-to-the-minute forum site.
Why do I think this? Guilty as charged!
Chuck (modeling Central Japan in September, 1964)
slightly OT, but i would love to see this forum impliment some kind of “recently visited” posts search or section. that way i can follow a post of interest which may contain replies to me that i might have otherwise missed because i didnt go digging for it. 
pardon me if this is already available. i havent found it yet.
Ditto there, Atomic: I have been up on the forum for a little longer than fifteen months; I think that when I joined there were in the vicinity of eight hundred and fifty pages. I wish the search function allowed you to go back to, say, page four hundred and twelve and start looking at previous posts from there. Going back that far two pages at a time will take from now until Christmas.
As usual, I agree with loathar. I really miss the “old forum”…
Tracklayer
CS should have a feature pack that can impliment those changes… maybe if someone can find the admin we can get him/her to add the features we’d like.
there is one forum i visit frequently at www.4gea.com that has a feature similar to what i described. i dont really like the way the forum is set up… but one feature i REALLY liked was called “replies to me.” when you clicked that, it hid all the other posts besides the ones where someone replied specifically to you and brought the relevant ones to the front… no matter if they were on page 1 or 412.
I’ve been “blow torched” more than once for bringing an older topic back up to the front page. My only intent was that if the topic contained good, detailed info then it would benefit newbies or new forum members.
I was saddened on a couple of occasions at how nasty some of the responses from a few of our fellow modelers were (“Guess who’s in dredge mode again again!”) or (“Why don’t you go help a seller on ebay?”) I would wonder why ignorant, underhanded comments like these are necessary to hurl at a fellow hobbiest? If a thread is of not of interest, then the flamer could easily move on instead of spitting venom. [;)]
BUT yet on a couple of occasions I got a very good feeling when a poster stated something like: “Great, this is just what I was looking for!” or “This is some good info!” [;)] This made the blow torching very easy to overlook. [8D][:D]
I have seen some thoughtful and cultured members point out that they are resurrecting an archived thread for some reason or other, which makes it clear that it’s an old topic. We often see the word “bump”, which also helps.
What bugs me is when folks edit a post that is well up (or down) the current thread, and don’t point out what they have changed. So, you see what is ostensibly a new post by bugsbunny, or whatever name you’d like to use, and when you open the thread, it’s daffyduck who has the last post, and you must scroll up to find…what difference in bugs’ post, exactly?
Actually, there is a function that allows you to view the topics to which you have posted replies. Its called “My Forums” and can be found in the MR Forum’s homepage menu line (where it says : Active Topics | Unanswered | Not Read | My Forums | Private Messages). Clicking on it will give you a list of all the topics to which you’ve posted replies, starting with the one with the most recent activity. Then, just like in the Forum’s topic list, click on a topic to get to the postings.
Unfortunately, there isn’t any way to list previously visited topics unless you have posted a reply.