Emergency air line cut

Easiest would be to get a new line. You can cage the brakes.

 

If you have a trolley valve, hook your blue service line up where the red one normally goes. Push red knob in, and pull trolley valve. You won't have trailer brakes, but you can move it until it can be fixed

 

After you get this fixed, get a replacement set of lines, made of rubber. Not plastic. Plastic snaps if you jack it too hard in the very cold weather during winter. And get another replacement set so that you have them ready to go the next time they snap.

Rbrtwbster's solution is a valid one, You can most certainly move that thing for a little bit with no brakes back there.

 

I carry airline compression couplers in various sizes. Cut the airline clean, and repair.

Or, if I can't repair it, I'd use a pair of vice grips to pinch off the airline just ahead of the break in order to stop the leak, and then cage whatever brakes weren't released. Service brakes still function with the spring brakes manually released.

In either case, 10-15 minutes and the trailer would be mobile again...repaired properly with the brass compression fittings or at least good enough to get it to a safe location if I had to pinch off the line.

 

Tractor protection valve won't allow that unless red line is also blocked/not pouring air out..

Going forward.. carry basic tools and extra air lines and glad hands, glad hand seals, teflon tape, various size ring clamps, extra coolant, oil, etc... eventually have quite the stash of things you may need during your travels. Of course, when you carry the spare parts you never need them so they are dead weight. You only need the simple thing you haven't added to your collection yet.

For a short distance and in a pinch I would cage the brakes to get to a place I can have the air line repaired or buy the parts to do it myself. A very short distance that would be considering you will have no trailer brakes or air suspension. Even a ta will do in this case.