The 1998 remake is better IMHO
When people talking about Pelham it's either about this original one or the remake from a few years ago. The original is higher rated on IMDB although I think both are quite on par.
Even though the remake makes some mistakes like the casting of Travolta (who always goes way over the top when asked to play a villain) and they try too hard to make a hero out of Denzel Washington, the original has the opposite problem of lack in depth in the characters. They're all quite stale and one-dimensional. The TV remake follows the original almost exactly but has more character depth. It also has quite an attractive cast. It was never released on DVD for as far as I know but it is shown from time to time on channels like TCM and MGM. Definitely worth a watch if you liked the 70's version.