 The Monaro Highway initially bore the National Route 23 route markers along its entire length , excluding the Eastern Parkway extension , which was instead part of Alternate National Route 23 . Now that each jurisdiction has converted to alphanumeric markers , it instead carries the B23 route marker along almost its entire length . The extension currently does not have a route marker . There is a duplex along the highway where it additionally carries the B72 route marker between the two sections of the Snowy Mountains Highway . Within the ACT , a section of the road is also part of Tourist Drive 5 . 
