The crossing at Spielfeld in Styria has been quiet in the past few weeks whilst the fence is being constructed. Police say that up to 3,500 refugees a day are currently crossing from Slovenia into Austria via the Carinthian border.
The head of the Styrian police, Major General Manfred Komericky, said that as soon as the fence is finished refugees will be directed to the crossing in Styria, which he said is capable of processing up to 11,000 refugees and migrants per day.
Austria's Interior Ministry has said that as many as 12,000 migrants may try to enter Austria per day.
Latest figures from the ministry show that last year 90,000 people applied for asylum in Austria, an increase of 200 percent compared to 2014, when only 28,000 applications were received. The majority of asylum applications were from Afghans (25,202) and then Syrians (25,064).
This isn't a record for Austria though. In 1956, Austria received more than 170,000 asylum applications from Hungarians fleeing the chaos and violence sparked by an uprising against the Hungarian People's Party, which was crushed by the Soviet Union.
Meanwhile, Germany has been sending an increasing number of migrants back to Austria since the beginning of January, Austrian police say. The reasons given are that many had no valid documents, whilst others did not want to apply for asylum in Germany but in Scandinavia.
Most of those sent back to Austria are from Afghanistan, Morocco and Algeria, Austrian police said.
Austria has been returning some migrants entering from Slovenia.