Tunnels
Manual Tutorials

Basic tutorial:

Starting
Setting up a bus service
Setting up a train service
Setting up a plane service
Conclusion

Advanced railway tutorial:

Two Platforms
Two Tracks
Basic Network

In game tutorial:

In-game tutorial
In-depth Instructions

Railway construction:
Building tracks
Building stations
Building depots
Placing signals
Buying & selling trains
Converting railways
Road construction:
Building roads
Building stations and loading bays
Building depots
Buying & selling road vehicles
Waterways construction:
Building docks
Building depots
Placing buoys
Buying & selling ships
Building locks and canals
Airport construction:
Building airports
Buying & selling aircraft
General construction:
Building bridges
Tunnels
Landscaping
Working with vehicles:
Setting vehicle orders
Refitting vehicles
Replacing vehicles
Grouping vehicles

Tunnels are useful for going under things you cannot move, or things that are too expensive to remove, like large mountains for example. You can't build a bridge over cities, stations or industries, but you can tunnel under them.

They can also be used in Junctionarys as vehicles can pass through them without slowing down, unlike with some Bridges.

Building tunnels

You can dig tunnels for roads and railways. Bear in mind that you can't change between road and rail in a tunnel without rebuilding the tunnel (although you can change between different types of rail).

Railway construction toolbar

Road construction toolbar

The screenshots in this tutorial show railway tunnels, but constructing a road tunnel uses the same steps.

Tunnels can not be dug on flat land

Tunnel can be dug here

To build the tunnel, just click on the sloped tile.

Congratulations, you have just dug a tunnel

Advanced tunnel building

If you want to tunnel somewhere that does not slope in the right place or direction, you will have to either raise or lower land to correct it and allow a tunnel to be built.

If there is a slope in an odd direction at the end of the tunnel, it will be automatically lowered so that the tunnel can be dug. However, you can't start digging the tunnel at such a slope; you must terraform it first.

Tunnel construction is possible even if it ends at an oddly-directed slope

The slope will be automatically lowered in order to dig a tunnel

Sometimes, the odd directed slope can't be lowered automatically because of obstacles on surrounding tiles. You will see an error window saying so.

Automatic slope lowering is impossible

The error message appears

Raise the land manually, so the tunnel end tile is a flat slope.

The tunnel can be built now

Limitations