(Updated by the editor to describe modifications)
Construction on the Woodshire Railroad began in the summer of 2004. The railroad consists of an outdoor 230-foot double track mainline and an eight track indoor yard. The yard and mainline are connected by a single track branch line that joins the main through a reversing wye. The ruling grade on the railroad is 2.2% and the minimum curve radius is 120 inches (O-240).
The first major construction task was to prepare a suitable roadbed for the mainline and wye. These features were constructed at ground level. To build the roadbed the top few inches of soil were removed leaving a shallow trench. Next, two rows of cedar stakes were driven into the exposed earth until their tops were at the surveyed elevation of each mainline track. Three quarter inch PVC conduit was then placed between the rows of stakes. The trench and stakes were backfilled with 3/8 inch minus crushed gravel. All of the gravel was carefully tamped flush with the top of each cedar stake. This created a firm gravel roadbed with good drainage characteristics.
Just like the real railroads this roadbed must be maintained. Each spring reveals the effects of Seattle’s famously rainy weather. Eroded ballast must be replaced and the track inspected for damage and settling. The encroachment of weeds and other vegetation must be kept at bay by occasional pruning. In contrast, the roadbed for the branch line is a post and beam viaduct built above the native grade. This portion of the railroad was the easiest to construct and has been much easier to maintain than the mainline and wye. UPDATE 2006: In the summer of 2006 the Woodshire undertook it’s first major modification to the roadbed. In the two years since the mainline opened tree needles clogging between the ties and erosion of the gravel roadbed had been the most consistent maintenance issues. To address both of these problems it was decided that ballast should be installed around the ties and across the top of the roadbed. The concept was that by filling the space between the ties with a solid material, whatever needles fell upon the roadbed could be easily removed with a cordless vacuum. A mixture of four parts roofing granules to one part portland cement powder proved effective during preliminary testing. Once whetted with a fine mist of water this mixture cures to a hard roadbed with a look similar to ballast seen on the mainline of the BNSF in the Seattle area. One of the keys to the mixture ratio was to get enough cement to solidify the ballast, but not so much that the ballast wouldn't drain. To date the ballasting project has proven very successful. UPDATE 2012: More changes and modifications are in process to compensate for wear on road bed and repair of oxidized connector pins)
Track and TurnoutsThe Woodshire’s engineering department and management elected to use stainless steel track and switches supplied by Gargraves for the outdoor portions of the railroad. The track was delivered in 37-inch lengths, which were formed to the surveyed curvature by hand. After forming, each rail was trimmed flush with the others to make a smooth joint perpendicular to the track. The track sections were then fixed to the roadbed with a one-inch wood screw into the top of each cedar stake. The Gargraves track has held up well since the mainline opened in the autumn of 2004. Each pinned track joint has a small gap to compensate for the expansion of the rail on hot days. In addition, the Woodshire traverses heavily wooded terrain that shades most of the mainline from direct sunlight. As a result, there have been no problems with thermal expansion. Another critical decision for the engineering department was how to operate the outdoor track switches. All commercially available electric switch motors contain steel components that will deteriorate over time. To avoid these problems the Woodshire selected E-Z Air pneumatic switch motors, which are designed for the outdoor environment. These motors are fed compressed air through 1/16 inch polyurethane tubing from electric solenoid operated pneumatics valves. The control valves and an air compressor are safely housed indoors under the railroad yard. The indoor yard was also constructed using stainless Gargraves track, but the switches were sourced from Ross Custom Switches and are currently operated by Z-Stuff DZ 2500 electric switch motors.
Control SystemThe entire Woodshire Railroad is controlled by the Digital Command System (DCS) from MTH Electric Trains. This system has three major components. First, a handheld remote control that gives the operator wireless access to each locomotive as well as control of the tack switches and some operating accessories. The remote control sends command signals via 914MHz radio to the second major component, the Track Interface Unit (TIU). The TIU relays the remote’s commands to each locomotive through the power distribution wires and track. The TIU also controls the third system component, the Accessory Interface Unit (AIU). The AIU is a bank of relays that can be used to operate electric switch motors and valves. A couple of competing interests had to be confronted when locating this equipment and the railroad’s power supply transformers. One was to keep the TIU close to the track. The radio range of the remote control is limited by strict FCC regulations and the signal generated by the TIU has difficulty with long wire runs. The other concern is protecting all of the electronic components from inclement weather. Two strategies were developed to deal with these issues.
First, for the mainlines, the twelve power transformers and two TIUs were fitted onto a cart which can be rolled inside. All wire connections from the cart are made with quick disconnects, so when the weather turns bad it can be moved inside in just a couple minutes. The power wires are distributed to the tracks through the buried conduit under the gravel roadbed. Eight buried watertight electrical boxes house barrier strips and buss bars that send feeder wires to the track every 15 feet. Originally these barrier strips were outfitted with #1445 18 volt light bulbs for improved track signal, but these have now been replaced by 2 watt 180 ohm resistors which won't burn out over time.
The second strategy for dealing with DCS was to place a second set of three transformers, a TIU, and two AIUs in the garage where the rail yard is located and modify the TIU's antenna. (Please note: modifying the TIU antenna is NOT authorized by MTH and may void any warranty). This indoor TIU is located near the outdoor branch lines and relays command signals to the indoor rail yard tracks and the outdoor branch lines. This kept all wire runs below 100 feet in length. However, this TIU is also connected to two AIUs which run the track switches on the entire layout, including the mainlines, with a bank of electrical relays. The problem with this configuration is getting the 914MHz radio signal from a remote being used out on the far end of the mainline to reach all the way back inside the garage to the TIU to operate the switches. The solution was to remove the original antenna built into the TIU, add a 50 ohm coax cable, and mount a new antenna near the mainline.
For anyone who is interested in the MTH Digital Command System, or has the system and needs help with wiring requirements and other information, it is highly recommend that you visit the DCS section of O Gauge Railroading magazine’s web forum.
BridgesThe Woodshire’s mainline also required the construction of two major bridges. One bridge spans a wide depression in the terrain. It was determined that this feature could be overcome by using two double track Pratt truss bridges from Atlas O. The key was to provide a stable footing for the two spans. To that end, three pre-cast cement paving stones were carefully set into the earth under the location of each bridge abutment. The abutments themselves are polyurethane castings purchased from Scenic Express. Die cast bridge feet, also from Scenic Express, were glued to the abutments and bridge spans. The second bridge is a curved wooden trestle that spans Ivy Gorge. As with the truss, bridge construction of the trestle began with the installation of paving stones to act as footings for each trestle bent. The bents were purchased from Grand Central Gems and heavily modified prior to installation. To prevent rotting of the trestle all wood elements were treated with Jasco Termin8 black wood preservative. This product has thus far proven effective and has the added benefit of giving off a realistic odor of creosote on warm days.