I have lived in the Netherlands for a number of years and double-decked passenger trains are the norm. I often use the system, and passenger aspects such as loading and unloading, through-corridors and access space are non-issues.
Although I am not a traingauge expert it seems that the Dutch have overcome some of their train envelope restrictions by depressing the lower deck so that passengers using this section step down into the train.
If the increased capacity benefits of such systems are attractive or necessary to improve key parts of the UK rail network then a review of other operators' experiences, starting with the one across the North Sea, would be a good place to start thinking outside the box. The view from the upper deck would be worth the trip!
Paul Hampshire (M), director, ARCADIS construction management group, Den Haag, P.R.Hampshire@arcadis. nl