Route size limits ?


I have a fictitious route that has been growing for the last seven years - currently the CDP size is 12 Mbs - and apart from loading times it seems to be all OK. My computer was custom built about 12 months ago specifically to cope with Trainz.
The question is whether a route can be "too big" or is there no limit to the project.


I have been asking this same question to many people here on the Forum.

Sure you can design a 2 baseboard wide route 1000 miles long, but load it up with 8700 railcars, 120 locomotives, 50 genus of twees, 50 genus of schwubbry's and grass's, 500 different textures, 5000 buildings (some designed with high poly sketchup), high poly track, and other splines, 1000's of signals (some of which will drop framerates by 5 FPS when in view) ... And your PC is struggling to decipher, how many railcars and locos are moving, or standing still, and exactly where they all are, even though they are out of the FOV, 50 miles away ... Trainz still feels all these multitude of assets, and is constantly checking each and every one of them every millionth of a second, not to mention calculating all the heights of billions of the 4 corners of each and every 10 m baseboard grid square ... and is choosing what to display just in the Field of View.

On a DEM, I would guess that it is best to keep a route under 100 miles long (is a route is hugely wide, and has 10,000+ baseboards, perhaps it would be better kept down to 50 miles in all directions).

You can do what you want on your own liquid Nitrogen cooled, 4.3GHz, $1000 video card, desktop super computer ... but if a user with a lower end laptop user downloads your route, Trainz may crash to his desktop.

The best checking device is loading your route, or designing your route on a lower end laptop ... it it runs good on an old beater, clunker, laptop ... it will run even better on a high spec PC.

If I were doing a series of routes I would break them down into many, many iPortal, or Portal segmernts.

NY to Phila
Phila to DC
Phila to Reading
Phila to Harrisburg
Harrisburg to Williamsport
Williamsport to Tyrone
Harrisburg / Enola to Mount Union
Enola to Harve DeGrace
Mount Union to Johnstown
Mount Union via the EBT RR and Robertsdale
Johnstown to Pitrcairn
Pitcairn to Conway
Last edited:
Thanks for the input - it would appear from the above I am a LONG way from any kind of limitation. I have never and do not anticipate uploading this or any
other route - my expertise regarding railways is limited and I like to keep routes as technically correct as my knowledge allows but do like to have the "eye-candy" effect. Perhaps some screenshots sometime - who knows ?

Where's Dragonharh when yah need him. He should be able to explain a bit more in this topic as Dragon's Pass is quite large, and is about to reach the limit in Trainz to add more onto it.
Your CDP size is pretty small, Ron. I wouldn't worry about it at this point. Keep in mind if this is only the route file, there are a few hundred other assets that need to be loaded up as well. CDPs are also compressed and are substantially smaller than the actual size of all the route files, and assets if they are included.

My routes CDP sits right around 50mb in size. ad its only about 20% done. (All track is in for about 60+ miles)

But I'd imagine that even with the most powerful computer, there is a software limit. A limit at which the game engine says "I quit."
My route is huge and covers a 5 county area, @ 10,000 baseboards (maybe twice that) and is 633mb, and runs on an old beater 1.73GHZ Vista integrated graphics laptop
Hi Everyone - Thanks for the info - most interesting. I am a mere amateur at this from what I read - I will keep going until something tells me otherwise.

If it is a hand-made terrain route, on flat baseboards, you could probably go on laying baseboards almost forever (like Bob Cass). A DEM really takes a hit on a PC, especially if it is huge.
DEM really takes a hit on a PC, especially if it is huge.

This is interesting, I'm curious to know more. Logically, regardless of DEM or handmade terrain both use the same baseboard (5m/10m grid), a flat baseboard should (data-wise) be the same as a mountainous one because they have the same number of vertices, so what makes a DEM so special?
Because a DEM (if you don't trim it down) has many more thousand distant baseboards, very much distant all tracks ... where as a hand-made route may only be 1 or 2 baseboards wide
I remember a discussion in these Forums several years ago, where regarding the maximum 'safe' size of a CDP. Does anyone remember what that was?
I seem to remember saving my route to a CDP, and the CM said that the file was too large, and could not save it ... IDK, maybe it was in one of my Trainz nightmares.
I recently sent John Citron a copy of a revised Hoosac East route, generated in TransDEM, covering a rough area of 15 miles wide by 45 miles long. The route has 5 meter boards along the roadbed, 10 meter board otherwise. The CDP is about 65, Mb, or 118 Mb in Surveyor. Any decent computer can easily handle that size.
John is one of those Trainzer's that tacks on route after route and assembled a massive hodge-podge of track and terrain. I'm sure he has a better feel than I for the practical size limit of a single route.
If you want to get an idea about a large route the game can handle, consider downloading the UMR. It is on the DLS. I think it is the largest route freely available on the DLS.
I remember a discussion in these Forums several years ago, where regarding the maximum 'safe' size of a CDP. Does anyone remember what that was?

I do as I started it last December when we were discussing moving stuff between us for the Hoosac Tunnel route. :)

If I recall, 500 MB is a safe size, although WindWalker said they've gone bigger than that to something like 850 MB. Keep in mind that 500 MB is the compressed size and the actual ground files and stuff is a lot bigger, and still doesn't count the other content when that's loaded. An uncompressed 500MB route CDP would mean one huge route, which I'm not even sure would load well in Content Manager. I've had troubles bringing in TransDEM saved routes which were probably that size uncompressed. CM barfed and crashed to the desktop on it. I ended up splitting the route into smaller sections, then junked it later because it was just too much to work on.

Because a DEM (if you don't trim it down) has many more thousand distant baseboards, very much distant all tracks ... where as a hand-made route may only be 1 or 2 baseboards wide

In that case you're not making a direct comparison. Of course an untrimmed 100-board DEM will be bigger than a 10-board handmade terrain, duh! Same thing with John's situation. Splitting a big route is not a problem, it's the time and effort needed to delete hundreds of boards one-by-one.

The problem here is that deleting baseboards in Trainz is a gigantic pain in the buttocks. Since there hasn't been any mention of any such improvement or a "quick baseboards delete" feature I doubt this will change in T:ANE.
Last edited:
Indeed, I spent the better part of a morning trimming boards from the route I sent John. That route can still loose another 20 or 30 boards yet!
Word of advice.......SAVE OFTEN!
Talk about mis-information around here.

On Win x86 you have a practicable size limit of approx 750Mb
On Win x64 you have a practicable size limit of approx 1.2Gb

These sizes are for editing purposes, anything larger than the above and you will not be able to save your routes.