Surely we all recognise that this site doesn't deserve the status of "World" heritage - its inscription was a farce. In the early days of "World Heritage", nominations used to be rejected frequently for only being of "Regional" or "National" importance - not a valid reason now. This railway clearly fitted one of those categories.
I think the Trans Iranian Railway is wrong on so many levels. We are talking about a railway in 1938. In comparison, the Union Pacific railway was built in 1870 crossing the huge expanse that is Western America incl. the Rocky Mountains. The Transsib (crossing icey Siberia) was built at the turn of the century. I dont see what key engineering feat was accomplished here. Answer none.
It was not built by Iranians but Americans and Germans. So even a national heritage seems weird. The state of preservation looks poor. And inscribing it as a complete railway without singling out the bits that needs to be preserved, means that de facto they should be put in danger as of this minute. I think they will modernize and rebuild and ...
Regarding regional and national importance, I feel that the argument nowadays is, we are a nation, our nation's history is part of the history of humanity and deserves to be praised and protected as world heritage. By that logic each and every national symbol could be inscribed as it is part of the nation's history. Worst example I have seen of late was Hortobagy, Hungary; a review is coming.
To me, and that pains me to say, the world heritage label is losing fast its appeal. At a certain point having the designation will no longer be a sign of quality. It should not be nationalitistic and it becomes.
Some orga changes are due. E.g. the committee should not contain any nations that apply for the status this and next WHC. The experts should propose sites. The total number of new sites should be limited...