Hi,
Berlin has a very long history of using double-decker buses reaching back to the era of horse-drawn buses.
The first new design after WW2 was Büssing's model D3U. The D3U used a slightly modified chassis of the heavy underfloor engine truck 12000 U13, that I showed here as a scratch built model a few years ago. Thus the D3U was a technically overly sophisticated and very expensive vehicle. Consequently only 39 D3Us were built and replaced in large numbers by the very similar-looking Büssing's D2U, a 4x2 with modern self-supporting body, that had almost the same passenger capacity and was much cheaper.
The D3U was in service until 1965. One vehicle has survived and can be seen at the Deutsches Technikmuseum Berlin.
My model turned out to be more difficult and more laborious than my usual scratch built trucks. I estimate that my sacrifice of time was somewhere between 1500 and 2000 hours.
