Complex sentence: The underground railway joined the omnibus and streetcar in transporting the working population, including those servants who did not live in the wealthy centres of cities; one result was that working-class and upper-class neighbourhoods might be separated by large distances.
Split into simpler sentences: The underground railway joined the omnibus and streetcar in transporting the working population, including those servants who did not live in the wealthy centres of cities. One result of this was that working-class and upper-class neighbourhoods might be separated by large distances.