I’ve chased a few rail lines more than once. Most of the time it’s just rusted iron and echoes, but there’s that old freight line in the hills where I found a rusted tin box half buried under a cracked rail. Inside was a stack of yellowed letters, nothing worth much but a map of a forgotten quarry. It wasn’t a secret signal in the modern sense, more like a relic of someone who thought the tunnel was a vault. I’ve never found a high‑tech cache, but the quiet places hold their own codes if you know where to look.

I’ll sketch the plan if you need it, but better keep your head in the dirt and eyes on the cracks. The old tunnels don’t wait for anyone, and the rust has its own secrets. If you think you’ll find tech, make sure you’ve got a map and a reason to leave the place. Otherwise, the only thing that gets out of the tunnel is the dust and the wind.