It's shown on the Survey plan as a 100 chain (20.117m) wide road with the southern alignment of the road not being surveyed. Lot 40 on CH311871
That's the ~5 acres of 'Suvd' rd, There is also shown ~10 acres of Res for Road. The remaining area on the Survey plan matches the area as currently shown on the QLD Smart Map (and confirms that the southern bdy of the road, and NE Boundaries of the property... remain unsurveyed)
Which suggests (but doesn't confirm) the 10 acres of res for road is still remaining (though it's not reflected on the property title.)
There may be other restrictions on access (Local or State.) Even if it's
formed road there can be access restrictions put in place that can sometimes be difficult to find as they're buried deep in archaic filing systems. So just because it's a road parcel doesn't necessarily mean it's public access.
Another hurdle would be the inaccuracy of the Mapping data you're using to view the road in QLD Globe. It's Digital Cadastre DataBase (DCDB) information and it's an land asset management system, not a mapping system. Some of the DCDB areas in qld are out ~500+m (or more....) There are places within the bounds of Brisbane Council that are inaccurate by 30+ meters. So while you could claim you are 'within the lines' of the DCDB, that might not reflect the actual physical location of the road of the ground.
Would be a fun survey to confirm the location of that road reserve though. Expensive, time consuming and likely difficult; but fun.