Complex sentence: On completion, the A48 route was diverted over the new bridge, making it the preferred route for through traffic, although in 2004 the new City Bridge on the Southern Distributor Road further downstream became the preferred route and assumed the route number.
Split into simpler sentences: On completion, the A48 route was diverted over the new bridge, making it the preferred route for through traffic. However, in 2004 the new City Bridge on the Southern Distributor Road further downstream became the preferred route and assumed the route number.