Wether you can access the road (with a car) or not is determined by the lift gate. The lift gate is closed whenever it is not safe to access the street (eg. during live shootings where the safety area crosses the street).
Even you could bypass the lift gate by foot or with a bicycle, it is not recommended because of the live threatening conditions.

There is no fix schedule when the lift gate is open or not, it depends on the army shooting times. The times are sometimes subject of change, can be looked up here: http://www.bundesheer.at/organisation/regional/noe/l75.php