Complex sentence: For almost all its length, the road is two lanes wide with one lane in each direction except when it passes through larger towns and cities where it may be expanded to more lanes as well as in the Hvalfjörður Tunnel.
Split into simpler sentences: For almost all its length, the road is two lanes wide with one lane in each direction. Where it passes through larger towns and cities it may be expanded to more lanes, as well as in the Hvalfjörður Tunnel.