<p>Where can I find pascal-style railroad diagrams to describe C++ syntax?
(As an alternative to EBNF)</p>

There don't exist any, as far as I know. The C++ syntax can't even be expressed in a proper EBNF - it's a context-sensitive grammar, and anything attempting to parse it has to be capable of processing C++ code at least as far as template instantiation and overload resolution (not to mention macros).