When driving the only road to Lapataia you will pass by "The train at the end of the world" ! That small museum-train is the southern-most train on earth and it was constructed between 1902 and 1909 as a train to be used by the prisoners in order to transport the wood of the felled trees to the town of Ushuaia. The bigest part of the rail-track does not exist any more, just a small museum-train uses a part of the original track of the former prisoner-train, and it uses locomotives and also wagons that were never used by the prisoners, even the narrow-gauge rails have a different distance than the prisoners had.
You will find this museum-train in a distance of about 10 km from Ushuaia and you will go through a part of the National Park, you will pass by the "cemetery of the trees" and go to Macarena Waterfalls, where a short stop of 10-15 minutes will give you enough time to step up to the waterfalls.
This sign-post at the end of the Highway Nr. 3 marks the end of a highway that starts in Alaska and combines several highways through different countries to the so-called "Panamerican Highway / Panamericana "
You really cannot always compare the quality of the roads with an ordinary highway, most of it is just a wide asphalt road with a wide track in each direction, so overtaking is only possible with no onward cars and mostly there will be a "hard shoulder" on each side, wide enough to park a car, but without asphalt but just uneven gravel, where you may drive on only in a small speed.
The very end of the Highway Nr.3 to Lapataia is quite narrow and just a sandy road through the National Park, at some places you will be lucky not to meet onward trucks or buses, because there is just space enough for a bus in one direction.
Mostly NO marks of tracks anywhere and on the way from Ushuaia to Rio Grande we also had quite a lot of places, where all of a sudden the ashpalt was missing on the ordinary road and you had to be careful, when driving there, so the maximum speed of mostly 80km on these highways really makes sense !