The trick in blender is to assign two UV layouts, one for the actual final texture, and another for the materials, then you take curved area you want the material on and on the material uv unwrap just that area and straighten up all the verticle and horizontal edges so they're straight, you basically get a grid pattern, then line that up with the texture you want, it bends it around the shape of the model without warping it, you then project that texture form the material UV to the texture UV layout. I'll see if i can find the video i learnt it from, it was actually a road making tutorial, and it's the section about putting textures around the curves, one of the most useful videos ive watched on blender.
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