When the man in the training films starts his day, he plays a record that later gets stuck in a scratch and repeats a certain refrain from the song. Later, being stuck in time is described as a phonograph needle being stuck in a vinyl record loop. Thus, this version of time travel represents time as fate, meaning unidirectional, the street analogy, as opposed to time as omnidirectional, meaning time as free will, move a grain of sand and you've changed the universe. If time is unidirectional, you can't change its path (you were fated to move that grain of sand--free will had nothing to do with it); if it is omnidirectional, you can alter (and thereby create) many branches of time, like a possibility tree, like Star Trek time travel.
I just saw "Dark Floors", a good sf movie, which develops a similar theme of being unstuck in time. It was interesting that in "Dark Floors", time gets unstuck while a handful of people are on an elevator, caught between the sixth and seventh floors: "Neither six nor seven/neither hell nor heaven." Which brings me to the Oceanic Six, or is it seven? counting Locke? Read Wordworth's "We are Seven" for further background on the six/seven mythos: In summary, Wordsworth asks a little girl how many siblings she has, and she answers seven: herself, five at play, and one in the grave; the narrator corrects her and tells her that makes six, that the one in the grave is gone; the young girl replies; No, we are seven: herself, five at play, one in the grave. And on and on. Lastly, check out "Slaughterhouse Five" for more on being unstuck in time. In interviews, LOST producers said that they were going to follow the path of unidirectional time and avoid the time travel of the TV show "Heroes."
Which brings me to my last point: Time travel as fate is predestination. If we were to unravel that vinyl recording and stretch it its length, the song would represent the past, present and future; the song never changes, no matter how many times you play it; neither does the song change if it gets scratched; the song merely becomes unstuck at a certain point, whether past, present or future. What one does to unstick it is to give the arm a slight push, jumping the needle to a future point in the song; then one pulls the arm back a bit, trying to put the needle back on track where it got unstuck, and ends up pulling it back into the past of the song: Thus, we have the jumps in fixed time, leaps in a predestined path. Locke is predestined to die in order to unstick time with his life, or his resurrection. In religious thought, only Christ could traverse the timeline; so, in this sense, Locke is the Christ figure. Alright, I'll stop here, but the religious aspects to LOST have been underappreciated in favor of sf: same mythos, different perspectives.
And no, I'm not a religious person; it's just that religion/faith versus science/faith has been the central theme since the show started. Even these threads have pondered whether the survivors were in heaven or hell, a time warp or Atlantis. Anyway, if you haven't read last week's TV Guide about LOST: Season Five, read it.
AC
P.S. The LOST producers also said this and next season will answer more questions than ask. Folks, we've made it over the hump. I look forward to this "time travel" theme with predestined giddiness.