Colored Flame Beacons

Truth be told the communication network setup by the dwarves in the Outh Mountains is probably the fastest in the world for communicating simple things. Different flames mean different events, and the number of pulses indicates how many stations away the message came from. Many a caravan has been saved due to this system, yet most dont even know it exists.

— Jasper Cameron, Leader of the Bronze Ravens.

Its really quite a simple system. You hollow out mountain top, or in some cases flatten an area at the top of a mountain, that overlooks a key trade route or pass, or from which you can see said mountain. Then you have some mirrors hauled up, usually polished mythril to withstand the heat. Then you have a massive supply of good dry lumber chopped hauled and stored. Then you get the powders in special containers so they dont go bad. Then you haul up more equipment so you can build a massive device so you can spin you mirrors around your fires to send pulsed messages. Then when something happens you either send a message, or pass the message along.
Most beacons are manned by 3 shifts of 8 dwarves around the clock. Once a signal is spotted from an adjacent beacon three things happen immediately. At the beacon the fires are lit. Towards the sending beacon a single white flash is sent, indicating the message is recieved. Towards the next beacon in the chain, the message recieved is sent on, adding one additional pulse (up to 4) of whatever color was recieved. Finally, a dwarf is sent down an emergency shaft to the dwarfhome or fort below to start the process of sending aide. Once help is on the way, word is passed up to the beacon so they can send a signal.

What The Different Colors Mean

White - Message recieved
Green - Help is on the way
Red - Raiders/Bandits/Attack
Blue - Storm/Flood/Avalanche
Purple - Rockslide/Mudslide/Bridge Collapse
Yellow/Orange - Forest Fire

It was the strangest thing I ever seen. We were getting ready to turn around, on account of the bridge across Fool's Folly was out. Suddenly from the back of a caravan there was a rucus and then a band of dwarves are cursin and hollerin telling us to get out of the way and how they got work to do. They showed up on the other side two, materials and tools all on hand, which is right strange cause there aint do dwarfhome in that part of the mountains and I'm sure I was the first caravan through the pass that year. Within a day that had the bridge made up good as new, watched us get on our way and then headed back the way they came. Its like they knew the bridge was out, but the rider I had sent back couldn't have told anyone, its a good five days to get to the nearest village, and thats with a horse.