Complex sentence: All transport services to the west coast are subservient to the weather-even the only roads into the west coast are blocked for days at a time by ice and snow during severe winter conditions.
Split into simpler sentences: All transport services to the west coast are subject to interruption by severe weather. In addition to closures of air and marine service, the only roads into the west coast may be blocked for days at a time by ice and snow during severe winter conditions.