[johnohara]

Early in my career I worked with a bunch of old school phone guys who told me they used to put a harness on a ferret, attached a fish tape, and sent the animal through a fairly long section of pipe in order to pull a 25-pair phone cable they were installing.

They literally "ferreted the pipe" and it was no big deal. There was a rhyme they used for remembering the correct sequence of the colored pairs too.

It wouldn't surprise me if one of the physicist's saw the phone guys doing this during construction.

[chiph]

A common technique these days is to attach the pull string to the handles of a plastic grocery bag, and then use a vacuum (shop-vac) on the other end to suck it through the conduit.

[derekp7]

I used that exact method to clean out a long dryer vent, except using the dryer blower to push the bag and string through.