Me meti en un vagón del metro y no he podido salir de aqui

(I jumped into a subway car and I haven´t been able to get off)

So starts the song el metro by seminal Mexican rock group Cafe Tacuba.

And often, yes, that is the way it feels, trapped, at the mercy of opening and closing doors and pauses in dark tunnels which bode never to end.

Workers´ solidarity at dawn, afternoon siestas,  clowns, blind singers and masters of monologue, vendors hawking and you and me and discretely photographing with phone, eye contact avoided and the next station approaches and then, the end of the line.