Command control is an essential element of the Operations Road Show layout.
Jack Ozanich put it succinctly when he said "I'd sooner give up Kadee
couplers than give up command control." We're largely in agreement with
Jack-- we cannot conceive of trying to run timetable and train order operations
while having to mess around with toggle or rotary switches to assign power
blocks. It would be just too distracting.
Digital command control was the obvious choice for our layout, given its
availability, its relatively low cost, and its inherent ability to support
functions other than simply controlling train speed and direction. We put
this extra capability to good use on the Operations Road Show layout, because
in addition to controlling the speed and direction of the trains, we wanted
to use it to:
- Control the signals for the train order system
- Control the six fast clocks installed around the layout, permitting us
to synchronize them as well as start and stop them simultaneously
- Control the alerter buzzers for the phone system
That last application was a last-minute solution to solve a problem we hadn't
considered in the design of the phone system. We think that it shows the flexibility
of digital command control quite nicely.
One other requirement we had for the system was the availability of radio
throttles. We felt these were necessary to provide the type of user experience
we wanted our guests to have- we felt that hunting for plug-in panels was
part of the experience that our guests could do without.
Although we'd been using Digitrax equipment for a few years prior to building
this layout, we looked at all of the major DCC brands available in the US
at that time (Digitrax, EasyDCC, Lenz and NCE) in order to be sure that we
would select the right system for our purposes. We chose to use Digitrax
DCC products for this project due to the availability of Digitrax supplies
from a local dealer (Michigan Model Train Center) and several other dealers
not more than 30 minutes' drive away, the availability and robustness of Digitrax's
radio throttles, and the availability of LogicRail
Technologies' LocoNet Fast Clock. Digitrax also had the best selection
of accessory decoders to choose from for automating our train order signals.
The Equipment
- The core of our Digitrax installation is a Digitrax Chief system which
interacts with:
- Four power boosters
- Two PM4 power management cards, controlling several power districts
in the Fiddle Yard and Lafayette Junction/East Yard area, as well
as the reversing section needed by the NYC/Monon/NKP interchange arrangement.
- Six LocoNet Fast Clocks
- Three DS54 I/O cards to interface with the dispatcher's train order signal
controls. For technical details of our train order signal system, see Building
the DCC-Controlled Train Order Signal System, elsewhere on this
site.
- Ten DS44 accessory decoders to control the train order signals, the indicator
lights in the signal control panel and the phone alerter buzzers.
- Two UR91 radio receivers. One is used as our primary receiver, and
the other is kept in reserve for use as an emergency backup or to
provide additional coverage if needed during a particular setup.
- 38 UP3 and UP5 throttle jack panels installed around the layout in case
we need to set up the layout in an environment that is completely inhospitable
to radio operation. They also serve as battery savers for the throttles
during sessions.
Even with all of the DS44 and DS54 accessory decoders, we do not use the
command control system to throw turnouts- all turnouts are thrown by hand,
using a variation of the old choke cable system.
We use up to 14 radio throttles, including a couple of DT400Rs,
three DT300Rs, ten UT4Rs and a couple of DT100Rs we keep in reserve.
A single UR91 receiver located at Lafayette Junction has afforded
excellent coverage across the entire layout area, and generally handles
the throttle traffic quite well.
Nearly all of the RJ12 cables we use to carry LocoNet signals around the
layout were custom-made using flat wire and connectors bought in bulk. In
a couple of cases we tried to use six-conductor phone extension cables purchased
from a local hardware store, but we found that we couldn't rely on the cables
working due to poorly-crimped connectors on an unacceptably high percentage
of them. We are great believers in using a cable continuity testing box to
test every cable before connecting it in place. Doing that has saved us many
hours that we would have likely spent diagnosing problems caused by defective
cables.
Layout Design Considerations
Although we decided from the outset to design the layout to operate exclusively
under DCC, the only thing that we did differently on this layout as a result
of our DCC focus was to use 12-gauge stranded wire for the track bus wiring.
This minimizes current and signal loss along the lengthy runs of wiring. To
ensure continuity through the rails, every segment of rail on the layout has
a feeder soldered to it. We do not rely on rail joiners to carry power between
sections of track.
Despite planning to use radio throttles, we installed 38 of Digitrax's
UP3 and UP5 panels in the fascia. The main reason for this was to ensure
that we could operate the layout if for some reason our ability to use
the radio throttles were impaired. This is recognition of the fact that
radio interference from outside sources is a variable are unable to
control when the layout is being used at a convention.
Taking a "belt and suspenders" approach to ensuring that
we could continue to operate in the event of failure of a radio system component,
we installed a second UR91 radio receiver panel in the Delphi/Clymers corner
of the layout. This provides an installed spare that we can bring up if anything
should happen to the "main" UR91 located at Lafayette Junction.
Since the layout is designed to be set up in only one configuration, we chose
not to install the LocoNet cable permanently into each module, with the attendant
connectors and jumper between them, but instead to custom-build cables for
the specific runs between UP-panels. We tagged and numbered each so that we
could identify its intended use. We do not feel that this particularly increases
our setup time as compared to connecting short telco cable jumpers between
each and every module. It also reduces the number of cable segments and the
number of connectors needed in the system.
In Use
To date, the only hardware failures we have experienced with our Digitrax
installation we from a batch of defective DS44 accessory decoders we
used to control the train order signals. We found that we had to continually
re-program them, as they would lose their memory whenever a short-circuit
occurred on the section of track from which they were taking their control
signals. Once they were replaced with new ones, we had no further problems.
One disadvantage we found to having the train order signals take their command
signals from the rails on the module is that it is possible for signal commands
to be missed if a short circuit on the track has shut down the power district
it's connected to. This is similar to a situation other modelers have encountered
when controlling turnouts using accessory decoders. Our solution to this was
to run a second two-wire DCC track signal bus solely for the train order signals
and phone buzzers beneath the layout. While we chose to dedicate a booster
to controlling this bus, we could have chosen to feed it from one output of
a PM42 power manager connected to one of the other boosters.
The radio system reliability has been excellent, and we have no complaints.
The only time we have experienced persistent reception difficulties due to
site environment issues has been the NMRA National Convention In Cincinnati.
Bringing the second UR-91 on line solved that problem quickly.
We
have discovered, as have other users of virtually all radio throttle
systems, that having the receiver mounted above head height improves
radio reception by drastically reducing signal loss dues to bodies being
between the receiver and a throttle. This was driven home to us during
a session in Saline where we had far more guests than we had jobs. At
one point, six people were viewing the layout from the aisle adjacent
to our UR91 radio receiver mounted in the fascia. While they were standing
in front of the receiver, we had considerable difficulty controlling
our locomotives. Once the crowd had moved on, the system resumed operating
as reliably as we are accustomed. We were able to duplicate this under
controlled circumstances at a work session later that week, and so moved
both the primary and back-up UR91 receivers up onto poles so that they
are approximately seven feet above the floor during operating sessions.
We have not had any reception problems since.
The four LocoNet Fast Clocks we have mounted facing inward at the four corners
of the layout are visible across the length of the layout. We also have
one at the Dispatcher's desk and one in the Fiddle Yard. The only thing
more we could wish for would be that they were available in an analog
design more fitting the era we're modeling, which dates to a good seven
years before digital clocks began to emerge. LogicRail Technologies
is working on just such a system, and displayed a prototype at the 2006
National Train Show in Philadelphia. Since all of the LocoNet Fast Clocks
can be controlled from any clock unit around the layout, or from a DT300
or DT400 throttle, it is very easy to adjust the time or clock speed.
During the summer of 2007, we added another LocoNet Fast Clock to the
system in the form of a wall-mounted clock in the crew break room in
the basement in Saline. Based on feedback from guests at the Great Lakes
Express 2007 operating sessions and clinics, we have also added a large
LocoNet Fast Clock high up on one of the room walls, to make it easier
for crew members under 5'2" tall to be able to see at least one
fast clock from anywhere on the layout.
Our
guest crews have been able to understand easily how to use the various throttles
after being shown only the speed controls and the reverse button. Digitrax's
introduction of the UT4R utility throttle was very welcome, as it provides
an inexpensive radio throttle with a familiar knob-and-direction-switch control.
Most of our locomotives are outfitted with headlights, Gyralights and a red
warning light. The headlight is controlled by the F0 key, as on most locomotives.
When the locomotive is running in reverse and F0 is ON, the headlight is extinguished
and the red warning light turns on, simulating Wabash practice. The F1 key
turns the Gyralight on and off, and the F4 key dims the headlight. A notation
on the locomotive card which accompanies each train's pack of car cards indicates
which locomotives are equipped with lighting effects.
In Conclusion
We've been extremely happy with our DCC installation, and the Digitrax equipment
in particular. Using DCC simplified the wiring to the extent that it was even
possible to have completed the construction of the layout in time for the
NMRA Convention in Toronto. It also relieves us of having to provide training
for power-routing block controls on the layout itself and spares our guests
the distraction of dealing with power-routing issues while getting their minds
around our implementation of timetable and train order operation.