How is tunnel price calculated in openttd

openttd

Is the price of tunnel linear or it is exponential by length? I am thinking about to dig a hole down in the ground with a certain frequency and connect holes with tunnels, if so the price I can decrease.

Best Answer

These data are taken from a new game with time paused, construction during pause turned on, and the ground on both sides demolished (to remove any difference caused by the cost of removing whatever was on the tile). Each tunnel's cost was estimated by Shift-Clicking on the position it will be build.

The costs are mostly exponential, but at the higher end for tunnels longer than ~45 tiles the curve seems to bottom out and become more linear. In almost all instance it definitely makes sense to break a long tunnel up into smaller tunnels whenever possible. In addition to being cheaper, this also increases the capacity for railroad tunnels, since only one train can occupy a tunnel at once because signals cannot be built inside tunnels.