In reference to ziplines.
How would we rescue a zipper who was halfway across a ride when the zipper gets stuck?
Sort of like trying to rescue someone stuck on a ski lift I would think. I ask because the kids in the neighborhood have made one and as I watch I think there will be a day when a rescue may be necessary.

Potentially tough rescue scenario if there is no way to reach their location from another tree.

If you know the quality of the zip setup (sound anchors and zipline) you could go down on the zip on a "horizontal" DRT or SRT system to reach the victim and then bring them back or lower them from their position.

A more time consuming option is set a second traverse line above their position and lower down off of that to reach them then take them straight to the ground of of your anchor.

Just off the top of my head, I've never researched existing protocols. There must be plenty of material on this in the experiential recreation/education field (ropes course, zips etc.)
-AJ

One other possibility for rope zips only is attach a lowering rope to one end of the zip with a suitably strong prusik or something similar, slack the zipline (cut it) and lower the victim to the ground under belay control. Lowering rope must be pretensioned to prevent shock loading when the zip is cut. Requires above average technical skill and lots of practice to achieve a safe rescue. Don't try this at home kids!
-AJ

I've done several zipline rescues over the years in a controlled training situation on ropes courses, and while those are from steel cabled ziplines, I'm guessing the mechanic on a rope zipeline would be pretty similar. It involves some skills that are handy to know for any rescue situation, so practicing it is a good idea. But since things can turn nasty on a dime, please search out qualified and experienced folks to watch over what you're doing. There are a lot of ways the rescuer can become a recuee him or herself.

There are typically four things that can lead to the need for a rescue. I'm sure there are more, but these come to mind. First, the zipline pulley can twist itself off the cable/rope and become jammed in place. This is pretty unlikely but having a single-wheeled pulley on a cable with a fast drop-off that bounces the rider does increase the odds of this occurring. Secondly, debris such as sticks, leaves, or the glove of a clueless rider reaching up to the pulley while riding can all bring the ride to a jammed halt. Finally, the rider may not reach the end platform from braking too soon or being on a zipline poorly designed by those not knowing what they're doing. Finally, the rider may become incapacitated and unable to be reached from the ground for rescue.

Whatever, the reason, the basic idea of the rescue is to attach a new belay system onto the cable above the rescuee, lower yourself down to just above the victim, transfer them to the new belay line either with an etrier (very easy) or a MA system (very cluttered) to unweight him or her, then lower both yourself and the rescuee to the ground. Cutting away the rope connecting the rider to the pulley is an option if he or she is injured and time is of the essence.

A couple of tricks to make things go smoother: Have a ground partner to help you by operating the belay and echoing back everything you shout out to describe what you're doing, especially during the inevitable "brain freeze" moments. In setting up the new belay, reeve the belay rope through a rescue figure 8 (the one with the two horns on it) and connect it with a carabiner (steel if the zipline is on a cable) to the cable/rope. The added friction allows you to lock off the belay with simply a thigh wrap and makes the two-person belay surprisingly smooth and easy. I've been able to lower myself and a beefy state trooper (that's a whole 'nother story) with merely an ATC Belay device.

Finally, when you reach the ground, if the rescuee is feeling dizzy, light-headed and unnaturally warm, DO NOT LET HIM OR HER LIE DOWN!!! You may be dealing with a case of suspension trauma. But that's another thread for another time.

Just thinking out loud here and this is situation dependent, meaning it won't work for every case. But, if the zip line is low, say 50 - 75 feet and the ground is clear to on anchor point, it seems to me that one could shoot at throwline over the zip line (away from the zipper) pull up a rope and walk/work the rope to the stuck zipper. He clips the carabiner attached to the end of the rope to his saddle or zip line pulley. You take the other end of the rope to the appropriate anchor and pull him to the anchor.

Also, you could tie a pull line to a steel delta and connect the delta to the zip line at one anchor, take the other end of the line to the other anchor and pull the delta to the pulley. Since the delta can't pass the pulley, you be able to pull the stranded zipper to the anchor. That should work even if he's unconscious.

An alternative to the delta might be just a loose loop knot around the zip line.

When I set up my zipline in my backyard, I use my 20 foot lanyard DRT to attach the person to the zipline pulley. I then give the person instruction on how to descend on the lanyard if they get stuck. I can belay them from the ground if needed. They always wear helmets and gloves. Havent had to use it yet but its there just in case.

I do something similar except single rope instead of DRT. Usually the way I set up a zip the rider will be off the ground when they reach the end. I hang a 15' length of 11mm Bandit off the trolley, Grigri on the Bandit, climber attaches to the Grigri. If the zip rider is not experienced in SRT descent there will be a facilitator at the end of the zip to instruct them how to descend the short distance to the ground. Depending on the the zip set up you can provide the rider with the right length of rope to get off the zip. A longer escape rope can be flaked and secured in a pouch on the rider's harness.

I like the Grigri or similar device for this use, a facilitator on the ground can belay the tail below the Grigri and control the descent rate if the rider is inexperienced. I'm with the zip rider in the tree where they launch and I show them where to place their hands so they don't grab the Grigri lever accidentally.
-AJ

Here's a little run I set up last year. The rider finished above the ground so I did the same lanyard thing. If they got stuck in the middle, higher than they could lower themselves on the lanyard, I suppose I could feed in rope at the MA pulleys to lower the whole zipline.