technical perfectiom is far overrated - this is a great shot. If you had time, a night time or dawn/dusk shot of this might work really well. I think that the grain works, though I would probably have tried a few different variations on the post processing just to see how they worked.
Interesting subject. Little bit grainy and you have some sensor dust spots that could be cleaned up. Good eye to see this shot. I'm curious, is this sign going up or coming down? Good luck in the challenge.