Curb Laying Machine

My friend Bobby asked me yesterday if I'd like to come watch them laying a thousand feet of curb for a section of road. There is a machine for this.

This is a time lapse (sped up 30 times) from a GoPro camera I mounted underneath the carriage of the machine. You can see the curb it just made stretching off to the left of the image (with people following behind to smooth it out and stick rebar in that will connect it to the road). Notice how the crawler foot keeps making small adjustments? This is automatic, with the whole contraption being guided by a tightly stretched string (which you can see peeking out behind the machine). A set of feeler rods run along the string and control the hydraulics that steer the machine.

Here's what it looks (and sounds) like in real time: http://youtu.be/Yxnr4yHGgE4

And here's an overall view of the machine in operation: http://youtu.be/zS8NUjdvl6g