On the imagery of the 'train': The train is a key motif throughout the film. It serves as a tool connecting the two protagonists, but also becomes an obstacle preventing them from meeting (like the heavy snow in Chapter 1). Do you think the train ultimately symbolizes 'encounter' or 'missed connection' in the film?

This is an insightful question that captures the most central and paradoxical visual imagery in 5 Centimeters Per Second.

Regarding whether the train ultimately symbolizes "meeting" or "missing," my view is: It symbolizes neither purely "meeting" nor purely "missing." It symbolizes a more brutal and realistic principle—the "uncontrollability" of fate and the "irreversibility" of life's paths.

The train itself is neutral; it is merely a tool. But its role in the film precisely reflects the protagonists' journey from "attempting to control fate" to "ultimately being controlled by fate."

Stage One: The Train as the Hope and Vessel of "Meeting"

In the first chapter, Sakura Chapter, the train is an extension of Takaki's willpower, a vessel carrying all his hopes.

Active Connection: Takaki actively buys the ticket, plans the route, and boards the train. At this stage, the train is his weapon to overcome distance and create a meeting. He believes that as long as he endures the long journey, this train will surely bring him to Akari.
Test of Will: When the train is delayed by heavy snow, it transforms from a mere vehicle into a "testing ground" for Takaki's resolve. His struggle with the train is essentially a struggle against "real-world obstacles." When he finally overcomes the delay and the wait to see Akari, the train fulfills its sacred mission as a vessel for "meeting."

At this moment, the train seems to symbolize: With enough determination, one can overcome obstacles and achieve connection.

Stage Two: The Train as the Barrier and Metaphor of "Missing"

However, by the film's end, the train's symbolic meaning undergoes a decisive reversal. It is no longer a tool for connection but becomes a barrier of separation.

Passive Separation: At the final railroad crossing, a train roars past between Takaki and Akari. This time, they are passive. They cannot control the train's arrival or departure. This train, like a suddenly descending curtain, forcibly interrupts their potential eye contact and communication.
Embodiment of Time: This speeding train perfectly symbolizes the swiftly passing, irreversible decade-plus of time between them. Time, like this train, carries immense, irresistible force, propelling their lives onto completely different paths.
Irreversible Tracks: Trains always run along fixed tracks; they cannot turn back or easily change course. This is the ultimate metaphor for their lives: Takaki and Akari are like two trains running on different tracks. They had a brief intersection (childhood), but are ultimately destined for their own destinations (Akari's marriage, Takaki's new life). They can glimpse each other from afar, but the tracks dictate they can never truly merge onto the same path.

At this moment, the train symbolizes: In the face of fate's grand trajectory, individual will is insignificant and powerless.

Conclusion: From "Extension of Will" to "Arbiter of Fate"

Therefore, the symbolic meaning of the train in 5 Centimeters Per Second undergoes a complete evolution:

It begins as the hope of "meeting," representing the innocence and resolve of youth that believed "man can conquer nature."
It ends as the reality of "missing," representing the powerlessness and acceptance realized in adulthood when confronted with the inherent tracks of fate.

Ultimately, the train symbolizes the normal state of life that exists between "meeting" and "missing." It tells us:

We can strive to board a train to meet someone (active will), but we cannot decide if the train will be delayed, nor can we stop another train from passing between us at the crucial moment (the uncontrollability of fate).

Makoto Shinkai uses the "train" imagery to perfectly close the philosophical circle of the entire film. It is both the story's starting point and its endpoint; both the embodiment of hope and the arbiter of reality. It carries the youth of everyone aboard, speeding along its predetermined tracks, never to turn back.