Mill Creek Central Trestle - Installing Beams I
The photo at right shows part of the beam storage area ---- the field near the south end of the trestle. Last spring we pulled them out of a fairly neat pile so that we could examine and measure each beam. This photo was taken on a misty morning in early September.
The first step is to move each beam to the "trestle fabrication" area behind the steaming bays. Photo shows Dick and the backhoe easily handling one of the ~600 lb I beams.
That meadow above the backhoe is between the tunnel and the trestle. Next summer trains will be moving across that meadow. The trees in the background show the start of fall color in early October.
The beams are cleaned and then eight 5/8" holes must be drilled in each. Photo shows Nelson Riedel using a really neat drilling machine to make the holes. This machine has a magnet base that holds it to the surface of the beam. After the magnet is turned on to clamp the machine to the beam, the position of the drill can be adjusted to make the hole in the correct place. This magnet base drill turned a dreaded task into a snap even for an old guy.
We also use the backhoe to transport the beams from the trestle fabrication area to trestle site. This beam goes between tower 1 and tower 2. The ends are wrapped with carpet (held in place by duct tape) to protect the beam and tower paint.
Dan Staron and Nelson are manning the winches to pull up the beam. The backhoe set the beam down with the north end between towers 1 and 2. The winches were able to pull it up hill about ten feet until it was centered between towers 1 and 2 and then lift it up the side of the towers.
The Jin-poles & winches worked great in that the beam was stable and we could work as fast as we wanted. (It was a bit exhausting for the old guy who was on the taller tower. Next time he'll know to pick the shorter tower.)
The beam slid in place perfectly. We removed the carpet pieces and clamped it down.
The photo above shows the pair of beams installed between towers 1 and 2. We were able to get the second beam up in about 45 minutes; the process is slick. Note that the Jin-pole angle has been reversed from the previous photos. We can do that by using a different hole for the lower bolt on the pole. The pole was left on tower 1 to be used to install the beams between tower 1 and the north abutment. The pole was left on tower 2 to be used to install the beams between towers 2 and 3.
Photo above shows the side view of the first set of beams.
This is the trestle fabrication area with two pair of beams being readied. All the holes have been drilled. A couple of the beams need the ends cut off (we'll wait of for one of the experts to do that). We'll then paint them before installation.
Status October 9, 2006: The beams between the north abutment and tower 1 are ready to go but first we have to finish building up the banks, That's Denny Varian running the backhoe.
These beams are pulled onto tower 1 from the north abutment. Nelson is cranking the winch and Denny is running the backhoe which is connected to the other end of the beam.
Note the added fill on the right of the photo. That will settle some and should become stable banks.
Jim Norris is directing everyone from the north abutment. He's also sweeping it clean before the beam is set in place.
The beams between towers 2 and 3 were hoisted next using the Jin-poles and hand winches. This time the backhoe could be positioned between tower 2 and tower 3 and lift the beam part way thus reducing the manual effort. Photo above shows the three spans.
This is an end view of the beams on the three spans. The beams are clamped to the top of the tower but need to be shimmed and have tie plates bolted between ends of the adjacent beams. Angles must also be bolted between the parallel beams at each joint to maintain proper spacing. The beams will be aligned at the time this hardware is added.
Denny and Jim Norris took a few minutes to remind us that building a trestle is fun.
Dick persuaded Clee Streets to trim a few braches from the backhoe bucket
The tree was trimmed to create this view. No sense in hiding your sign behind a tree.
Status October 13, 2006: We have another pair of I beams up for a total of 4 spans ---- we're half way across. Photo above shows the trestle from the east side. The trees are loosing leaves so the south end is less hidden. The leaves will be gone about the time we get the last spans up ----- good timing.
The photo on right shows the view from the south abutment.
The thing sticking up is one of the Jin-poles covered with plastic. One of the manual winches became difficult to use when the previous beams were installed. That manual winch was replaced with an electric winch hence the cover.