I think the factor that made Threads so powerful, particularly if you saw it in the early 1980s, was that appreciating how close we were to that scenario actually happening.
The Road is, I would agree, rather more bleak but as the threat is rather ill-defined it doesn't quite have the same sense of dread, at least to me.
However, I was 18 when I saw Threads for the first time and it did rather leave a a mark, as did the related "QED: A Guide to Armageddon" which is a chilling look at the effects of a nuclear weapon on a large city.
The Road is, I would agree, rather more bleak but as the threat is rather ill-defined it doesn't quite have the same sense of dread, at least to me.
However, I was 18 when I saw Threads for the first time and it did rather leave a a mark, as did the related "QED: A Guide to Armageddon" which is a chilling look at the effects of a nuclear weapon on a large city.
https://www.youtube.com/watch?v=9GJttnC8PoA
The bit where the effects of the heat of a nuclear weapon are shown on meat in a butchers window (around 6:40) literally gave me nightmares.