Here is a quick overview of how to get the achievements for x number of tunnels used.

Requirements:

• unlock the scenario "Many Tiny Tunnels" by getting a score in classic of 1000 in Zurich.

Follow the following steps:

1. Load the scenario
   
2. Place lots of short tunnels as shown in the screenshot below
   
3. EDIT Recent reports in the comments indicate that you need to get a small score of any amount for it to count towards the achievement. Thanks Dragatile and FGV!
   
4. Let the location overload and incur a game loss
   
5. Repeat the first three steps

If you wish to check the achievement progress once you have lost the level after placing your tunnels. Close down the game and check the in progress achievements.

I hope this guide helps. Thank you