Building an Inverted Train Tunnel

Part of the process of building up the new layout has involved creating a few train tunnels of varying heights and widths. Up until recently I’d gone for either very narrow tunnels using the 1×12 arch pieces, or wider, more boxy looking versions using half arch pieces. Neither of these ever looked fantastic, they did the job but it all looked a bit flimsy and unconvincing. I did build a more detailed tunnel entrance once, using some old flex hoses threaded through technic bricks to create a wider portal. I’d like to revisit that idea one day.

This new tunnel needed a bit of an odd shaped footprint as one side would need to connect to the waterfall module. The first steps were to rough out a basic template to build on using big plates and bricks. They aren’t pictured here, but the longest bricks available are 2×24 and I’d highly recommend picking up a few as they’re incredibly useful for measuring studs across distances.

Once the basic template was sorted, I started to build up one side of the inner walls. Because Lego doesn’t offer a great range of inverted slopes, my idea was to use normal slopes but build the whole arch upside down and connect it using SNOT bricks. It actually worked better than I’d expected, although there was a lot of trial and error in getting everything to stay in position securely. The same technique works well for double track tunnels, and the aforementioned 2×24 bricks are super useful for adding strength in wider versions.