Complex sentence: For a period of time it was also the only highway in the US never to experience an automobile accident until 2005, when the island's firetruck nicked the island's ambulance on the highway while responding to a call.
Split into simpler sentences: For a period it was also the only highway in the US never to experience an automobile accident. All that ended in 2005, when the island's firetruck nicked the island's ambulance on the highway while responding to a call.