That's actually the third span in that location: the grade and concrete piers from the second span (which washed out in 1909, IIRC) are still visible - there are also several submerged railroad cars from an unsuccessful effort by SP to save the second span. There's a good piece in an article about Elvas that ran in the Winter 2016 issue of SP Trainline that covers the bridges.
Should information be added about the old wooden trestle that burnt here be added? There are some interesting statistics here - http://discuss.amtraktrains.com/index.php?/topic/10901-fire-...
According to https://books.google.com/books?id=Tp85AQAAMAAJ&pg=PA807&dq=s... both this bridge and the WP bridge were constructed around the same time.