Sketchup is great. A number of software houses are using it to create objects because it's so intuitive. All objects in Sketchup must have no textures if you are going to import them into something like Blender. Blender like Gmax have learning curves. It would have been nice to have for Sketchup a direct exporter into Trainz but alas there is not. I've used Blender for years. Textures must be in the form (as a bitmap or tga image for example) 64x64, 128x128, 256x256, etc. In Blender you apply a material then a texture on top. Since every object is limited to 16 materials what you can do is make, say a 1024x1024 bmp image, then put all your textures on that image (say 64x64 images) that way you'll have plenty of "room" to texture in terms of the materials.