Complex sentence: Following the construction of the tunnel, of railway were rebuilt for higher speeds, shorter distance and natural protection from the weather; this was built in five stages, opening between 1995 and 1998.
Split into simpler sentences: Following the construction of the tunnel, of railway around this area was also rebuilt to achieve higher train speeds, a shorter overall distance, and to maximize the natural protection from the weather. This was built in five stages, opening between 1995 and 1998.