Looks impressive (from the pictures I can see online)! Designing and building bridges is not my area of expertise, but I can see why it took them 6 years. Funnily enough, there are some things that aircraft wings and bridges have in common – they are long, flexible structures – and there are famous examples of where this can become a problem… I’m thinking of the Tacoma Narrows Bridge for example, that collapsed in 1941 – the same year it was built – after suffering from self-excited vibrations that we typically call ‘flutter’. There are videos online, where you can see the bridge swinging and twisting until it breaks – and that was a modern cement structure! Another example is the London Millennium bridge, which started to swing and twist in certain wing conditions and when people walked over it at the same pace. It’s expensive when the engineers get it wrong!