Complex sentence: The Queensways were built as dual carriageway major roads in the 1960s and 1970s, however in recent years many have been rebuilt and downgraded and now far more resemble city streets.
Split into simpler sentences: The Queensways were built as dual carriageway major roads in the 1960s and 1970s. However, in recent years many have been rebuilt and downgraded and now far more resemble city streets.