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Accu-Tie Loop December 2022 - Final Tunnel Update

Wow, what a few weeks of work will do for a project! The main structure of the tunnel is now complete. The wrapping of the tunnel with rubber roofing material was competed on December 6th with a group of four getting together to complete the task. Kudos go out to the dozen plus individuals who came out at different times over the last six weeks to help in the construction. The tunnel project could not have been completed in the timeline we were targeting without you!

Assembly of the tunnel components began on October 28th, after completing the excavation of the hole, the drainage and floor prep was complete. You can read more about the prep on the October 27th, 2022 blog found here.

For several months this past summer we went back and forth on how we were going to construct the tunnel. The three main ideas we were considering were building it out of wood, some form of culvert, or using a method that we've used before, constructing them out of old used oil tanks. There was an initial desire to construct it out of wood but after examining the cost of wood versus used oil tanks we initially went with the oil tanks. We were able to locate sufficient tanks to complete the project until we determined, on a final survey, that the tunnel needed to be 100 feet, not the 60 feet we had originally estimated. While we would have likely been able to acquire additional tanks, each of them were 8 feet in diameter and in lengths of 10 to 15 feet. The tanks would need to be transported to the track, a major task in itself, and then we would need to be able to get them to the tunnel site. The road to the tunnel site, located on the back of the property and in the woods, is not the greatest and trying to move these tanks to the tunnel site would require removing a significant amount of trees, not to mention how in the world would we move them in the first place. The tanks would also require us to torch the ends and, due to the curve in the tunnel, we would need to torch the 15 foot tanks in half. While we thought that this was doable, it was certainly fraught will numerous risks and difficulties.

We then looked at finding culvert piping that we could use, similar to what Bill Bryan has used at his Canton, St. Paul & Pacific track in Georgia. We were able to locate a couple of suppliers but ran into three issues, availability in the timeline we would be constructing it, the cost of the culvert pipe and the biggest issue, the inability to effectively curve the pipe to match the track route in the loop.

So again we looked at using a wooden structure. Luckily, lumber prices had come down significantly from when we had originally evaluated those costs, the bad news was we now had 100 feet of tunnel and not the 60 feet we had first evaluated. But the beauty of wood is that it is workable, it could be designed for a change in grade and curved, the component sizes are manageable, the transportation to the track and onto the tunnel site in the back of the property was quite doable, and, in the end, Coshocton Lumber agreed to sell us the lumber and materials at cost. These benefits and the opportunity to acquire the materials at cost led us to move toward constructing it out of this material.

The next decision was what would the structure look like, knowing that it would have to handle significant loading, both on the sides and the top. Jim Henry got on a couple of forums asking how wooden structures had been constructed in the past and Bob Vanderkarr, who was visiting several tracks that had wooden tunnels at that time, grilled the owners, asking them pertinent questions about their tunnels. Load calculations were completed, based on the depth of the tunnel from the surface, with Tom, Jim and Dick went through a couple iterations before coming up with an acceptable design that had an acceptable footprint to support it on softer ground as well as the structural spacing needed to maintain the opening. In the end, the structures would be constructed with 4"x6" ground treated lumber, with the base timber being treated for marine use and each of the structures would be a maximum of 16" on center. The structural supports would be wrapped with ground treated 2x6's, the same used for our wooden ties, and then the completed tunnel would be wrapped in rubber roofing on the sides and top. With the proper drainage now completed to keep the water away from the base of the structure and the assembly of the 76 structures in late September and early October by Dick, Jim, Brody and Bob, we were ready to go!

We were originally planning to use the large Kabota to move each of the structures into the cut to start assembly but due to the weather, and the fact that we didn't want to track mud into the cut, we decided to take a different tact. You see, the stone that we were constructing the tunnel on was actually being used for its drainage and leveling of each structure so bringing mud into the site could negatively impact our leveling and drainage design, So as an alternative, it was suggested that we use the Case backhoe to drop the structures into the cut, which worked great! The picture of the first installed structure and the addition of some of the subsequent structures are shown below.

So the tunnel is 100 feet in length but on the east end of the tunnel there is an area that historically is very wet and there is also drainage from the pond at the back of the property that creates a stream that normally runs 9 months of the year. So we weren't sure exactly where we were going to end the tunnel on the east side. Therefore we started in the middle of the tunnel, at the top of the grade and worked our way out, in both directions. The tunnel, from the west (clockwise looking down) is on a 63 foot radius and is climbing at a 2% grade. The grade helps with drainage, getting the water out in a reasonable amount of time without softening the base, and adding to the fun of climbing in the tunnel as well. Around 30 feet in the tunnel the track moves into a 30 feet straight section that continues to climb at 2%. Nearing the end of the straight of way the tunnel levels and begins to drop at a 2% grade and at roughly the same time enters into another 63 foot radius for the remaining 40 feet, exiting right near the drainage for the pond. As stated in the prior update, the tunnel cuts through the Kittanning Coal Seam, which is constantly seeping water and draining into and around the tunnel area. Bob V. and Dick worked hard developing an appropriately graded ditch to get the water moving away from the site. Final grading will happen next year or maybe a pipe might go in to eliminate the large ditch. The pipe you see in the ditch is for the road crossing that had to be removed to correct the drainage that we had initially done. This was done using the level in the picture.

Each of the 76 structures had to be leveled and tamped, along with ensuring that the tunnel was following the correct grade and the curved parts of the tunnel were appropriately spaced. While the outside of the curves and the straight of way are on 16" centers, the inside of the curves were actually at less than 16". In order to compensate for this Jim calculated the spacing of the inside of the tunnel curve then built spacers that would fit between the vertical columns of the structures, both outside and inside, to properly space the supports. This worked out great with each of the supports pointing toward the center of the radius of each of the two curves (which each have a separate radius point). You can see the spacers in some of the pictures below. The spacers made the installation so much easier. The crew just placed a spacer at the top and bottom on each side of a newly added structure and screwed the spacer to the support and voilà, we had the spacing we needed. As far as determining the distance away from the radii, we surveyed the distance and then anchored 1/2" plastic conduit to the ground representing the outside edge of each of the supports. All the crew had to do was make sure that the outside edge of each support they placed was touching the conduit. During the support installation the track would like to thank Luke Anderson, Dick, Bob V., Jim Henry II, Brody and Mark Betlem for coming out during the days we were installing the supports. Not everyone could make it every day but we had the help we needed, when we needed it, to get them in place before the siding crew came in.