Complex sentence: From then on, many heavy trains could be pulled over the route once the tracks and civil engineering structures had been upgraded for the increased axle weights, including the Trisanna bridge at Wiesberg Castle in 1964.
Split into simpler sentences: From then on, many heavy trains could be pulled over the route. As a consequence, however, tracks and civil engineering structures for the increased axle weights had to be prepared, including the renovation of the "Trisanna bridge" at "Wiesberg Castle" in 1964.