Was wondering if this rig might be familiar and if so, could one explain how it steers the Bore Sleeve (not sure if that is the correct term)? A bore pit was dug on each side of the railroad right of way. Shoring system panels using the dual struts on those two sides. Plates on one end and the other end with sheet piling. Pits were 'mirror image' as to the right of way with the shoring side nearest the right of way. Green painted spiral wound pipe welded joint for the Bore Sleeve with a full flight auger bit already staged inside. Truck crane did the rigging and handled a hydraulically opened and closed "clamshell" to remove spoils from the pit. Bore Sleeve sections butt welded together as the bore continued. Then the concrete pipe (with the double male end) pushed into the Bore Sleeve and the pipe joined together with an oring and a steel epoxy coated ring. Looks like they set up a steel track system and the unit would pin itself to the track then push the pipe. And turn the auger as necessary. This bore had to be close to 100 feet and the service is storm water (gravity). Fall would seem to be a concern. ~ And when that ram pushes the sections of the pipe in the finished bore, what keeps those steel rings in place since the concrete pipe had no shoulder that I could see. I could visualize other headaches/problems in achieving that "friction fit ring" at the pipe joint to slide into place with the idea it remains centered over the pipe butt joint ..... issues nightmares such as sliding instead of remaining in place when the second pipe is pushed into it etc etc. Are those plywood circles placed at the concrete pipe ends to preclude chipping and spalling from the push pressure? I can usually catch someone's attention and ask these questions but when I stopped by there the workers were feverishly working or they were being bird dogged as they crossed the tracks' right of way and all that expensive plowed in fiber was clearly the attention getter for a lot of inspectors and vacuum potholers as well the railroad " hall monitor " [name we give to the hired watchers on some job sites LOL]. Even though I visited the border of the site a couple three times, I wasn't able to catch up with these workers say as they were closing up for the day to allow me to converse about some of these inquiries. Thanks.
I saw it done on our job site about three years ago using steel tube about 18" diameter - no concrete liner, the tube just stayed in there. The sections on that one were butt-welded together as each one was pushed into the bank, until finally the other end appeared out the far side. "Steering" the pipe was done by offsetting the angle of the end of the next tube before welding. Alginment was checked IIRC using a laser target. Sorry can't recall any more details than that.