The title promises spring, but the poem gives us only a list of warnings you might see on a road or a train platform. That mismatch is the joke, and also the point. The signs can be read as stand-ins for the season: "Under construction" suggests things being built or begun, much as spring is a time of new growth. "One way" and "no stopping" hint at time moving forward and nothing able to hold it back. "Mind the gap" and "yield" sound like gentle advice to be careful and give way.
The speaker never says how they feel, and that restraint shapes the mood. The tone is dry, a little playful, and quietly observant. The capital letters make the words sound like commands, yet together they read almost like a small set of instructions for a season of change. Spring here is not soft or sentimental. It is busy, unstoppable, and asks us to pay attention and to give way to it.