[Curmudgeon]

Frost, water, and traffic are concerns but according to one paving company site, asphalt roads start breaking down in 3-4 years as the asphalt binder becomes more brittle. With sealing and a good maintenance program (something probably lacking in AtE), a properly engineered asphalt road can last more than 25 years (same source). I would suspect on that basis that most roadways will, at best, have been reduced to gravel if a couple of generations, where a generation is about twenty years, have passed. That around 25 year mark can be lessened given: heavy traffic (not too likely AtE itself but it may have been scheduled for maintenance that just never happened), water, frost heaving, or chemical action or any combination of those factors. (Gas and oil aren't good for an asphalt roadway either.)

Even if a roadway remains reasonably intact, signage and markings won't. Anyone with a vehicle that performs at levels near current vehicles is going to need to be alert for sharp corners, places where speed should be reduced, possible rockslide areas, pavement that is slippery when wet, bridges that ice over before the rest of the roadway, steep gradients, animal crossings and hidden entrances.

Aids such as rumble strips, cat's eyes and bott's dots will likely be absent by this time, so the driver will need some form of regime that keeps him alert while behind the wheel.

Gullies/ditches are unlikely to have been maintained, so there will be extensive sections that have been water damaged and, while not the issue it would be today, vegetation has likely grown right up to the edge of the roadway and vision at intersections is badly obstructed. For the occasional surprise, the odd tree might have grown up through the middle of the roadway thanks to a convenient crack the seed landed in.