Imperial Gate System - Twilight Tunnels

The Order of the Twilight Tunnels was, a "chartered group" from the Imperium. The main function of this group was to create and maintain a series of gate stations. To support them in that regard they had four branches, Gatesmen (mystics), Swords (Security for Gate Stations and eventually to be the first line of defense for the Imperium), Scouts (Finders and Explorers), and Builder (makers of the Gate Stations). The Order is the backbone of the Imperium, allowing it unprecedented communication and transportation. This advantage allows them military and trade advantages that can not be compensated for.
Duterious, The Imperial Histories, Vol II

The Imperial Gate system was a general network of gate points. This was used for general transportation, trade, and communication for the public.

There was a smaller Imperial network, used for shuffling troops and supplies, as well as Imperial officials and couriers. Its existence was not a well known fact.

The GateWays
It is a common misconception that the gates themselves allowed for instantaneous travel. It was the members of the Order that created the gates. Since creating a gate from "the ground up" takes many master adepts and dozens of apprentices, The Order began to utilized enchanted Gate Frames.

Gate Frames are two standing stones, approximately three meters tall and three meters apart. They are carved in a grooved pattern that is both esthetic and mystical (enhancing the misconception that the gates were magic). The pattern does known mystic runes that are somewhat helpful in the process included in the groove pattern.

Normally one gate goes to one place, but there are enchanted runes allowing gate frames to be used to multiple gate frames. Publicly, they are all "one way", but that is not completely true.

Each Right Gateframe has eight GateStones in eight sockets. These are baseball sized(9cms) are embedded into the Gate Frame and can be turned. They are grooved with a line that connects two of pattern. The patterns are set up that each ball socket has one to four potential positions (connecting two of the rune appearing lines. The Gatestones must turned in the correct ways to complete the mystic flows, allowing for a gate to be easily created.

By utilizing the enchanted gateframe, a journeyman spell caster (who knows the spell), can create and maintain a gate (allowing near instantaneous travel) between the two frames. A powerful or experienced journeyman or master can create a gate to any appropriate gate frame from any appropriate gateframe.

In short, each gate location has an "address". The targeting gateframe must have the target gate's address AND the target gateframe must have its address in place. This allows for one gate to contact any number of exterior gates. The gatestones connect the "circuit" allowing energy to flow in the right patters, making the gateframe active. With enough power and skill, you can work around these circuit blocks.

Between uses, the stones are scrambled around to make the gate deactivated. Removing one stone from the set deactivates the gate.

The Laws of Usage
1) Every city/ town is graded either as HOME, Core, Periphery, and Frontier.

Home is the home of the Order, which happens to be the capitol of the Imperium (insert great country/ empire). Core are older, well established, major places. Most of the Core Places have a geographic proximity. (Using American examples - think of it as New York and neighboring borroughs, Chicago, Boston, Los Angeles, Seattle, St Louis, and such.) Periphery are places which have been established for a while. They have not been accepted into the core because of their geographic "insecurities" or because they are not as large or developed (San Francisco, San Jose, Denver, San Antonio, Austin, New Orleans). Many places chafe under the periphery status, thinking they should be core by now. Frontier are newer gates, ranging from just opened gatepoints for mines and resources, places of geographic insecurity (Hawaii), or recent connections (Anchorage).

2) Gates are only to be opened to exit gates in their own grade or out one grade up.

This is the law, not a restriction of the magic. It controls the flow of travel and is a security measure. Since there is no one to open a gate at frontier site, any overrunning or catastrophe can be limited to just that site. So Home gates only open to Core sites. Core gates can transfer to other Core Gates or Periphery gates. Periphery gates might connect to other Periphery gates or Frontier sites. (Certain Periphery sites serve as hubs for other geographically nearby gate sites, to increase the flow of raw material or goods.)

Rogues searching for new gate points have been known to violate this law.

3) No one who can open a gate is allowed through a gate to a Frontier and some Periphery sites.

This prevents someone from coercing someone into opening an illegal gate direction.

4) Gates run much like a railway/ airport. There is normally only one gate at a station, but some important ones have up to eight. The Gates are opened at specific times to specific destinations, allowing people and carts to pass through.
This could be circumvented, but for safety's sake is not.

They are timed that only one gate is open at a time. This is another security measure, more than the listed safety reasons.

Interior travel occurs before exterior travel. So it is fast moving from core to periphery, only slowing down slightly passing to the frontier. It might take three times as long, if not requiring overnight stays, to move from frontier to home.

5) Gatepoints are kept in a large plaza or a huge building that serves as a central hub for locations. Near these gate plazas or stations are Order Houses and business that support travellers or are involved in trade. This is not a law, but simple practicality.