Up Vertex Buffer Size - Seems to only happen on one map.

gm_subwaytown_beta2 if map is relevant.

So I’m on Singleplayer, and on the above stated map after a while (e.g. 5/10 minutes or something. I didn’t really pay attention to time but it’s in minutes) I’ll get the;

Please up vertex buffer size.

Now I recall there being a solution to this but I’ve forgotten completely.
I was told roughly; “I think it’s something to do with the RAM it needs”.

Now it’s a small map (small on top but under the ground it’s a very big map).

Now this map has gotten me more interested, because with DasMatZe’s train, you weight the passenger carriages to 5000, and the main engine by 5000. Wheels go to 1500, thrusters are at 10,000 with weights of 75 (will derail somewhere so change the weight) x4. It works flawlessly, more better than trainconstruct, oddly enough.

So what’s the reason and solution for “Up Vertex Buffer Size”?

(On the map rp_evocity2_v2p I have never recieved this error. In fact this is the first time I’ve recieved this error on the new computer)