The picture shows a simple looking access ladder job which is in fact complicated in that the roof concerned has no sqare corners with all surfaces at peculiar angles. (Architects!)
Sizes and bevels were taken and the ladder made up and measured carefully, on completion it was stripped and hot dipped galvanised that gives it a minimum of 20 years free of maintenance. The ladder is also in an awkward corner with no easy access to be gained, so the ladder was made up in hand-able sections that could be hand carried to the site position. The final problem was that the ladder is actually suspended above the glass roof and isn’t supported at the base.
Well done to all those concerned for this bespoke job.