Complex sentence: The National Highway's Kilometre Zero is the Democracy Monument on Ratchadamnoen Avenue, and the Railway's Kilometre Zero is the Erawan Elephant Monument, in front of Bangkok Railway Station.
Split into simpler sentences: The National Highway's Kilometre Zero is the Democracy Monument on Ratchadamnoen Avenue. And the Railway's Kilometre Zero is the Erawan Elephant Monument, in front of Bangkok Railway Station.