Another reason why HS2 is costing so much is that some of the structures are overengineered. The V pillars on this viaduc look good, but concrete really isn’t made for this type of application. This requires a lot of post tensioning and reinforcement which adds to the cost of the structure. You can also see that they built a temporary viaduc to be able to reach the work site with cranes. There’s also quite a bit of falseworks to hold the V pillars while they cure. Had they chosen another designs, they probably could have done away with the falsework and the temporary viaduc.
