Tunnels

Tunnels are points where the road goes under a through or underground.

Subterranean Tunnel
These Tunnels exist under layer 64. They are very long and never come above the surface. They kind of act like subways.

Independent ST Tunnels
These tunnels connect the two system ST Tunnels from two different cities.

System ST Tunnels
These tunnels make up a who city of tunnels usually under a city on the surface.

Extreme Tunnels
These huge tunnels are usually found on the lowest surface. Tunnels have to be 501 or more to classify.

Large Tunnels
These tunnels go through the largest mountains. They are between 101 and 500.

Moderate Tunnels
These are commonly found on the roads beneath the highlands. They measure between 51 and 100

Small Tunnels
These little guys are frequently found near the highlands and never exceed 50 blocks.

Tunnel Ledger
Similar Bridge Ledgers, Tunnel Ledgers connect an lower edge and an upper ledge with a staircase going through the side.