It's the dative form.
Dative is almost extinct in Norwegian except for a few phrases, like "opp/oppe", "hjem/hjemme".
Oh thanks! I get 'hjemme/hjem' and the others with respect to whether there is motion or not. How does 'tide/'tid' work?
I guess motion through time? Don't expect there to be any consistent rules about dative, as it's mostly extinct. So most Norwegians won't even know what it is, they know know some dative expressions.
There are only two phrases with 'tide' AFAIK, "i tide" and "på tide"(about time, as in "it's about time something was done"="Det var på tide at noe ble gjort")
"I tide" seems like an unnecessary addition. You can't not catch the train on time.
Helt riktig! In this case "catch" is a poor translation. "Å rekke" = "To reach". The sentence should be translated "They cannot reach the train in time," the essence of which is "They cannot get to the train in time."
I think what UK English would actually say is "they don't have time to catch the train"