You will need (exact numbers are decided by tunnel dimensions):
- 1 inch (or larger) PVC poles
- 1 inch (or larger) wooden dowels
- 3 inch (or larger) metal, pipe clamps
- 1/2 inch rebar (2ft lenghts are good)
- (2) 1 inch "T" connectors
- tarp or covering
- covering fasteners
First, imagine a tunnel to be like a ribcage. You have the spine and the ribs. Now jab the ribs into the ground and you've got a tunnel shape. For useful purpose, a "rib" extends from one end inserted into the ground to the other end inserted into the ground.
You will need two (2) pieces of rebar for each rib (because you will have to attach it to the ground on both sides). Space your rebar out evenly according to the number of ribs and lenght of your spine (you will have two rows of rebar). Be carefuly to not the sides too cloes together, it might break. Pound the rebar into the ground about 1 foot. A tape measure makes it easier to get everything even.
Wooden dowels: you will need to make one (1) for each rib. Cut the wooden dowels into 1 foot lenghts (or buy them that way). Wrap a couple layers of tape around each end.
Join two lenghts of PVC by inserting one taped end of a dowel into a open end of one piece of PVC (put it in about half way), and then pushing the other lenght of PVC onto the remain half of the dowel. The tape should help make this a snug fit. Assemble all ribs in the same manner.
To join the ribs to the spine: Line the spine (another piece of PVC) along where the two pieces of PVC connect. Wrap a metal, pipe clamp around the rib and spine, use a screw to tighen. Do this for all ribs.
Put the "T" joins at the ends of the spin to keep the end ribs from slipping off while you get it set up.
Get at least one more person to help you set it up. Inset one end of the rib onto a rebar stake. Have the other person place theirs on next. This is an interesting balance and you'll just have to give it a try to get the hang of it. More people make it much easier to do (but it is possible with just 2). Be sure to line up the ribs with rebar directly across from it.
Drape your tarp or covering over it, secure with fasteners of some type. I suggest canvas cloth and bungee balls, they have worked well for me. However, you'll need to insert grommets and coat it with a waterproofer if you use a canvas drop cloth. But it is easier to paint than a generic blue tarp (and prettier too).
Thanks to BobbyG for helping me perfect tunnel constructions and this list of supplies and thanks to Magorn for the original instructions.
disclaimer: I've have set up a tunnel that has evolved into the one I'm describing (we made it the dumb way -- with bolts and connectors -- got smarter, and made it this way) many times. However, if these directions do not work, it is not my fault. You just need to work on your engineering skills and not rely on directions from others.
written on September 24, 2002; modified on September 24, 2002.