Complex sentence: The street is a single-track road for the majority of its length, and to avoid problems with vehicles meeting on the slope and being unable to restart, the northern half has been made a one-way street for the main descent.
Split into simpler sentences: The street is a single-track road for the majority of its length. To avoid problems with vehicles meeting on the slope and being unable to restart, the northern half has been made a one-way street for the main descent.