^ I have been eyeing up a trip for end of summer or October, so all we can do is hope! Either way I guess it may discourage some visitors from visiting this season if postponed, which could be a bonus for a first time trip... fill your boots with Helix re-rides.
Liseberg has finally overcome the issues with the construction of the tunnel!
They have been continuously pumping out the groundwater, which has been causing them problems, and finally were able dig further down. The tunnel has now reached its final depth of 8 metres. Currently they are preparing to pour the tunnel's concrete floor.
Preparing to pour the concrete floor.
Now a summer opening is seeming realistic.
Since work on the station and electrics has been continuing while they were having their tunnel problems the park have said once the track is completed it won't be long until they can start testing.
The track for the drop while sitting on the car park has been wired up in preparation.
Information and pictures from Liseberg's Valkyria Facebook group and screenshots from a video released by the park.
Wonder what they'll do about the groundwater when the tunnel is operational? I mean, building a structure below the groundwater level is like pressing a plastic cup down in a tub of water. As the structure is hollow, it is likely to be lighter than the volume of groundwater it displaces - i.e., it will float. The groundwater will press the structure up to an equilibrium level, like the waterline on a boat.
If they install a drain pipe to lower the groundwater level, every structure that is already "floating" in the soil will sink further down, since the equilibrium level is lowered. This also includes structures standing on the surface, since the soil loses some strength when it is drained of groundwater.
The other solution is to allow water to seep into the tunnel (relieving the pressure from groundwater by letting it flow freely - there isn't that much water coming in every hour, so it would be more of a trickle than a flow) and then just pumping it out. The Opera house in Oslo uses this technique to stay in place, there are chambers below the basement where water flows in and is continuously pumped out. But that's an "active" and quite expensive solution.
I guess there is a third solution, just weighing down the tunnel so the equilibrium level goes down to the groundwater level. But that would require a huge amount of concrete.
I don't doubt they've got a solution for this ready. Underground structures tend to be really well planned, after all. Just wondering which solution they are going for.